METHOD AND CONTROL DEVICE FOR SECURE VERIFICATION OF AN ELECTRONIC TICKET

Description

[0001] The present invention relates to a method for the secure verification of an electronic ticket and a corresponding control device for the secure verification.

[0002] More and more consumers are choosing to purchase tickets online, especially for buses and trains, but also for concerts and other events. When purchasing tickets online, consumers usually have the option of having them sent by mail or email. Alternatively, they often have the option of transferring the ticket directly to their smartphone.

[0003] The two variants in which the ticket is delivered by email or transferred directly to the consumer's smartphone are generally referred to as electronic tickets.

[0004] If the consumer requests delivery by email, the ticket is often sent in PDF format. The ticket data is then usually stored in the form of a barcode, making it easy and quick to read by a ticket inspection device. If necessary, the ticket data is also displayed in plain text.

[0005] If the consumer chooses to transfer the ticket directly to their smartphone, the ticket data is loaded directly onto their smartphone via a dedicated app. This option is particularly popular for train tickets. For example, Deutsche Bahn AG offers a dedicated app (also known as DB Navigator) in which a passenger's electronic tickets can be stored.

[0006] As soon as an electronic ticket is to be checked, the data, often stored in the form of a 2D barcode (frequently an Aztec code), is read by a ticket inspector's device, according to current technology. The inspector then receives all relevant information about the electronic ticket within a very short time, such as the passenger's name, the booked route, the booked mode of transport (e.g., regional express or ICE), the booked class (1st or 2nd class), the booked seat (if applicable), BahnCard options, etc.

[0007] In this way, the ticket inspector can quickly check whether a passenger has booked the "correct" ticket and thus has a supposedly permissible right to use the selected means of transport.

[0008] However, the procedure described above only allows the inspector to check to a limited extent whether the ticket is an original, a forgery or a copy, and whether the passenger is actually entitled to use the selected means of transport.

[0009] Therefore, there are already various approaches to making tickets forgery-proof. To increase security, today's electronic tickets often contain additional verification bits generated from the ticket data using an algorithm. If a fraudster attempts to manipulate the electronic ticket data, for example, by changing the information about the booked route, the ticket inspector or their inspection device can detect the tampering with the ticket data.

[0010] While the mechanism described above protects against unauthorized manipulation of ticket data, it does not prevent a fraudster from copying the entire electronic ticket. For example, a fraudster could take a screenshot of the barcode associated with an electronic ticket and transfer this screenshot to one or more other smartphones. To prevent this problem, most electronic tickets are now issued in a personalized format. Therefore, in addition to verifying the electronic ticket, the ticket inspector can also check the passenger's personal data and request identification. If the passenger's name displayed is identical to the name stored on the electronic ticket, the passenger is considered authorized.While the above-described procedure for verifying electronic tickets in combination with the verification of personal data can be considered relatively secure, the described two-step verification process (verifying ticket data and personal data) is quite time-consuming in practice and therefore very unpopular with both users and inspectors. Furthermore, the two-step verification process is practically impossible in some cases, for example, if a user claims not to be carrying an ID.

[0011] Even if the electronic ticket can be read automatically within a few seconds, the additional manual verification of the passenger's ID card or passport is relatively cumbersome. Often, the passenger only has their electronic ticket at hand, but not their identification documents. This means that verifying the personal data of a single passenger can sometimes take a minute or even longer. With several hundred passengers whose tickets need to be verified, this results in a considerable amount of effort.

[0012] Consequently, the railway operator would have to hire additional security personnel to ensure a complete and thorough check of all travel authorizations. Alternatively, it could forgo the additional security personnel and accept only a superficial check of passengers' authorizations, for example, by partially or completely foregoing the verification of personal data.

[0013] In practice, this often leads to only electronic tickets being checked, rather than the passenger's personal data. However, this approach is unsatisfactory, as it does not provide the operator with sufficient protection against fraudsters.

[0014] EP 1 750 220 A1 discloses a method for creating and automatically verifying electronic tickets. In this method, user data is stored in a user database of a ticket server, and service provision data is stored in a service database of the ticket server. An electronic ticket is created by the ticket server and stored on the user's mobile terminal, wherein the electronic ticket is based on user data from the user database and / or on service provision data from the service database. Furthermore, an electronic control key for verifying the electronic ticket is stored on a controller's mobile terminal, and the electronic ticket stored on the user's mobile terminal is verified by the controller's mobile terminal.The verification is carried out by means of data transmission via an NFC interface between the user's mobile device and the controller's mobile device.

[0015] Furthermore, DE 10 2010 017861 A1 describes a method for handling electronic tickets. The electronic ticket is stored on a portable data storage device of a mobile user device. In this method, the electronic ticket is generated offline using the portable data storage device of the mobile user device.

[0016] Based on the problem described above, the object of the present invention is to provide a method and a control device for the secure verification of an electronic ticket, in particular an electronic bus and / or train ticket. A further object of the present invention is that the method for secure verification is designed to be efficient.

[0017] To achieve this object, a method for securely verifying an electronic ticket is proposed according to independent claim 1. Further preferred embodiments of the present invention are defined in the dependent claims. In the method according to the invention, the electronic ticket is stored on a first mobile terminal associated with an end user, and the ticket is verified by a second terminal associated with an inspector or a control system. The method according to the invention comprises the following steps: Sending a request message from the second terminal to the first terminal via a first communication channel; sending a response message from the first terminal to the second terminal via a second communication channel, wherein the response message is signed by the first terminal and wherein the second communication channel is either identical to the first communication channel or different from the first communication channel; verification of the signed response message by the second terminal; and confirmation of the authenticity of the response message by the second terminal, provided that the authenticity of the signature could previously be verified by the second terminal.

[0018] The method according to the invention, and in particular the signature of the response message by the first terminal, offers an additional protective mechanism for effective protection against fraud. The first terminal, on which the electronic ticket is located, is requested by the second terminal to send a response message. This response message is signed by the first terminal. The digital signature attached to the response message can then be verified by the second terminal. A private key of the first terminal is used to generate the digital signature. The subsequent verification by the second terminal is carried out using a public key of the first terminal. The public key and the private key of the first terminal together form a key pair and are mathematically linked.Key pairs are generally known from cryptography and are used in asymmetric encryption methods. Such a key pair can be generated, for example, using a standard elliptic curve cryptography method or the RSA method.

[0019] The public key can, for example, also be included in the reply message. Alternatively, it can be arranged that the public key of the first device is stored on the second device, or on a storage medium that the second device can access via a network connection. Since the second device has access to the public key of the first device, it can verify whether the signature of the first device is valid. If the signature is invalid, the second device can conclude that the electronic ticket is a forgery or a copy.

[0020] According to one embodiment of the method according to the invention, the second terminal can be embodied as a mobile terminal. This is particularly advantageous if the method according to the invention is to be used, for example, on trains. Alternatively, however, it can also be provided that the second terminal is embodied as a stationary terminal. This can be particularly desirable if the method according to the invention is to be used in conjunction with an access control system or an access system. Such an access control system can, for example, have electronically controlled access barriers or automatically opening access doors and carry out an automatic check of the electronic tickets or the travel authorization of a consumer.

[0021] The first terminal according to the method according to the invention can preferably be designed as a smartphone. The second terminal can also be designed as a smartphone.

[0022] In addition to the control mechanism provided by sending the request message to the first terminal and the signed response message to the second terminal, the ticket data can preferably also be transmitted to the second terminal. There are various alternatives for transmitting the ticket data. For example, it can be provided that the ticket data, which is stored in a 2D barcode, is first displayed on the first terminal. The second terminal can then read the 2D barcode and check the ticket data (in particular the route, the booked class, etc.). In this context, the ticket data can be referred to as being transmitted via an optical communication channel. The second terminal can then send a request message to the first terminal to verify the passenger's identity and request confirmation by means of a signed response message.

[0023] According to a further embodiment of the method according to the invention, the ticket data can be transmitted within the response message. Thus, the entire control or communication between the control device (second terminal) and the consumer's terminal (first terminal) takes place in a total of two steps (sending the request message to the first terminal and sending the response message containing the ticket data to the second terminal). In this case, the ticket data can be stored either as a 2D barcode or in another format (e.g., in text format).

[0024] Furthermore, according to one embodiment of the method according to the invention, it can be provided that the request message includes a verification message. The verification message can, for example, be a character string generated according to a random algorithm or a pseudo-random algorithm (in particular, a randomly generated text or a randomly generated number) that was previously generated by the second terminal. In particular, it can be provided that, after receiving the request message containing the verification message, the first terminal encrypts this verification message with the private key and subsequently transmits an encrypted representation of the verification message to the second terminal. This transmission then takes place via the response message.The second terminal can then decrypt the encrypted verification message using the public key of the first terminal and thereby verify whether the first terminal actually has the key assigned to it. In this way, the security of the verification checking method according to the invention can be further increased, since it is ruled out that the response message is already generated before the verification message is generated. The verification message generated by the second terminal can, in particular, be different for each control process. This makes it virtually impossible for a forger to copy a response message in their possession or to reconstruct a response message from a response message known to them that would be recognized by the second terminal as a valid response message.

[0025] According to the present invention, the request message comprises a verification message containing a random number of length L generated by the second terminal, where L >= 1, and the response message contains a representation of the random number generated by the second terminal, encrypted with a private key of the first terminal. For example, the random number may be 64 bits long. According to one embodiment of the method according to the invention, the random number may further be 128 bits long. Using a particularly long random number makes it particularly difficult to forge or copy the electronic ticket.According to this embodiment, the first terminal cannot, in particular, use a copy of a response message previously generated by another terminal, but must generate the response message containing the encrypted representation of the random number itself. Otherwise, the second terminal would determine that the first mobile terminal is in possession of a supposedly correct private key, but has encrypted a different number than the random number previously generated by the second terminal.

[0026] According to the method according to the invention, it is also provided that the response message contains a digital certificate originating from the service provider that created the electronic ticket or from an entity classified as trustworthy by the service provider (trust anchor). The digital certificate can, in particular, be designed as a public-key certificate. The digital certificate can have a public key which, together with a private key of the service provider, forms a key pair. In principle, it is possible for the public key to be contained in the response message and transmitted to the second terminal device, for the public key to be stored on a server, or for the public key to be stored on the control device.The trust anchor (hereinafter also referred to as an entity designated as trusted by the service provider) determines whether the first mobile device is suitable to host the trusted client application. If so, it equips the mobile device with a unique ID, a key, and a certificate or verification code. The verification code is easily verifiable offline by all authorized participants in the system and confirms the trustworthiness of the client application.

[0027] The digital certificate can, in particular, contain information about the certificate issuer and the certificate recipient. The digital certificate can also contain information about the hash function used. For example, the digital certificate can specify that the first device uses SHA-1 or SHA-256 as its hash function.

[0028] The second device can use the data contained in the digital certificate to verify whether the owner of the first device is actually authorized to use the electronic ticket. The digital certificate can also be signed using a private key of the service provider. The service provider's public key associated with the private key can be stored on the second device or on a storage device accessible via a network connection. This allows the second device to verify whether the certificate was actually created by the service provider. Furthermore, the digital certificate can contain information regarding the certificate's validity period. For example, the digital certificate can contain the date on which the certificate was created and a validity period (e.g., 3 months).The second device can then verify whether the certificate is still valid at the time the electronic ticket is checked. If the certificate is no longer valid, the second device can conclude that the owner of the first device is not authorized to use the ticket stored on the first device.

[0029] The method according to the invention also provides that the response message comprises the electronic ticket, which, in addition to the ticket information, also comprises a first digital identifier of the first terminal, and the electronic ticket contains a digital signature of the service provider; the response message comprises, in addition to the electronic ticket, a second digital identifier of the first terminal generated by the first terminal; and the second terminal confirms the authenticity of the response message only if the first identifier contained in the electronic ticket and the second identifier generated by the first terminal are identical.

[0030] The identifiers (IDs) can, in particular, be a digital fingerprint of the first terminal device. Specifically, a hardware fingerprint or a software fingerprint of the first terminal device can be used. A digital fingerprint enables the unique identification of a terminal device. A hardware fingerprint can, for example, include a processor ID, a memory ID, and / or a graphics chip ID. The digital fingerprint can also be composed of or calculated from the aforementioned IDs. In this embodiment of the method according to the invention, it can be provided, in particular, that the ID of the first terminal device is queried or read when the end user registers with the service provider or when purchasing the electronic ticket. For this purpose, an application can, for example, be provided on the first terminal device (trusted client application) that reads or retrieves this ID.generated. For this purpose, a hardware ID (e.g., the CPU serial number or the RAM serial number) can be read and forwarded to the service provider, so that the service provider then creates a personalized electronic ticket containing the purchaser's data and / or the ID of the end device (first identifier). In this way, the ticket is linked to the purchaser's end device. The trusted client application protects the application's private key and data on users' mobile devices and is checked and authorized by the trust anchor for this purpose. Since the electronic ticket is also signed by the service provider, an unauthorized person who does not possess the service provider's private key cannot manipulate the electronic ticket data.During ticket inspection, the second device can verify whether the ticket was actually created for the passenger's first mobile device, or whether it was created for a different device and subsequently copied to the first device being checked. In addition to the data contained within the electronic ticket, the first device's identifier is also queried during the inspection. For example, the second device can read a hardware ID from the first device (second identifier). The second device can then compare the first and second identifiers. Only if the two identifiers are identical is the authenticity of the response message confirmed. This provides a particularly secure verification process.With the key and signature function established in the trusted client application, a ticket issuing system or control device can determine its trustworthiness and the authenticity of the unique ID itself. The ticket issuing system inserts this ID into the data of a ticket to be issued before signing this data and sending it back to the client application. The ticket is thus bound to this ID.

[0031] According to a further embodiment of the method according to the invention, it can be provided that the identifier of the first terminal is used independently of the principle of the request message and the response message described above. In other words, to achieve the above-mentioned object, a method for the secure verification of an electronic ticket is proposed, wherein the electronic ticket is stored on a first mobile terminal assigned to an end user, and the ticket is verified by a second terminal assigned to an inspector or a control system. The method according to the invention comprises the following steps: Sending a verification message from the first terminal to the second terminal via a communication channel, wherein the verification message comprises the electronic ticket, which in addition to the ticket information also comprises a first digital identifier of the first terminal, and the electronic ticket contains a digital signature of the service provider; the verification message comprises, in addition to the electronic ticket, a second digital identifier of the first terminal generated by the first terminal; and the second terminal confirms the authenticity of the verification message only if the first identifier contained in the electronic ticket and the second identifier generated by the first terminal are identical.

[0032] An advantage of this embodiment is that the security of the method according to the invention is further increased, since it is virtually impossible for the electronic ticket, which preferably contains a signature of the service provider, to be tampered with. It is also virtually impossible for the identifier of the first terminal, which can in particular be a hardware ID, to be tampered with. The identifier of the first terminal is preferably generated by an application provided by the service provider. Therefore, it is particularly difficult to tamper with this application to transmit a forged identifier.

[0033] Alternatively, the second terminal device can only confirm the authenticity of the verification message if the identifier contained in the electronic ticket and the identifier stored in the digital certificate are identical. This provides a particularly secure procedure, as manipulation of both the electronic ticket and the digital certificate is virtually impossible.

[0034] According to one embodiment of the present invention, the method according to the invention comprises the following steps: Sending a verification message from the first terminal to the second terminal via a communication channel, wherein the verification message comprises the electronic ticket, which in addition to the ticket information also comprises a digital identifier of the first terminal, and the electronic ticket contains a digital signature of the service provider; the verification message comprises, in addition to the electronic ticket, a digital certificate signed by the service provider and comprising the digital identifier of the first terminal; and the second terminal confirms the authenticity of the verification message only if the identifier contained in the electronic ticket and the identifier contained in the digital certificate are identical.

[0035] Furthermore, in an alternative embodiment of the present invention, it can be provided that the second terminal confirms the authenticity of the verification message only if the identifier stored in the digital certificate and the identifier generated by the first terminal are identical. This ensures a particularly high level of security, since manipulation of the identifier stored in the digital certificate and the identifier of the first terminal is virtually impossible.

[0036] In principle, there are three different ways to verify the identifier (comparison of the ID stored in the ticket with the ID stored in the digital certificate, comparison of the ID stored in the ticket with the ID read by the first device, comparison of the ID stored in the digital certificate with the ID read by the first device), with each variant having the advantages mentioned.

[0037] Furthermore, the method according to the invention can be provided that the reply message contains a timestamp and that the authenticity of the reply message is only confirmed by the control device (second terminal) if the age of the timestamp is below a predetermined threshold. For example, it can be provided that the authenticity of the reply message is not confirmed if the timestamp is older than 60 seconds. This additionally prevents a reply message generated by a terminal from being transmitted to and duplicated by an unauthorized first terminal. In this case, a generated reply message is only valid for 60 seconds and cannot be used beyond this period. This further increases the security of the method according to the invention.

[0038] According to one embodiment of the method according to the invention, the timestamp can be integrated into a barcode, in particular a 2D barcode. For example, the second terminal can send a request message to the first terminal, and the first terminal can generate a response message in response to the request message, which transmits the relevant information encoded in a barcode. The second terminal can read the barcode and check whether it is actually a recently generated barcode or whether it was generated, for example, one or two hours ago and possibly transferred to the inspected device later. In this case, the inspector could request the passenger to provide identification.

[0039] It can also be provided that the response message contains a digital certificate in which a security indicator is stored, which characterizes the fulfillment of specified security requirements by the first terminal device. The security indicator can contain information relating to the result of a previous security check of the first terminal device. In particular, it can be provided that when the first terminal device is registered with the service provider (ticket server) or by an entity classified as trustworthy by the service provider (trust anchor), a security check of the first terminal device is carried out, which checks whether the terminal device fulfills the security requirements specified by the service provider.During the security check, for example, it can be checked whether the first end device has a current version of the operating system and / or whether antivirus software is installed on the first end device. If the first end device has an outdated operating system or no antivirus software, the security attribute can contain corresponding information that characterizes the first end device as insecure. The security check can also check whether the first end device is a routed smartphone or a routed tablet. If the check determines that the end device is routed, the security attribute can contain corresponding information that classifies the first end device as insecure.The security check can be standardized and performed identically for all devices, or it can be individualized and tailored to the specific device being checked. For example, the security requirements for devices running Android may differ from those for devices running iOS. This allows for individualized device checks without unnecessary verification steps. By providing a security indicator, individual services can be controlled based on the specific device. For instance, devices that meet the service provider's security requirements may be authorized to purchase tickets, while those that do not can not.For example, it can be stipulated that end devices that do not meet the security requirements can only retrieve information about the connections. It can also be stipulated that the second end device refuses to verify the ticket if the first end device does not meet the specified security requirements. The digital certificate containing the security indicator can, for example, be included in the electronic ticket or alternatively as a separate element.

[0040] According to one embodiment of the invention, it can be provided that the security indicator is designed as a binary security flag, which contains a value equal to 1 if a previous security check of the first terminal device has shown that the first terminal device meets the specified security requirements, and contains a value equal to 0 if the previous security check of the first terminal device has shown that the first terminal device does not meet the specified security requirements.

[0041] In this way, the results of a previous security check of the first terminal device can be encoded in a single bit. This limits the amount of data transmitted within the framework of the method according to the invention.

[0042] Furthermore, the inventive method can provide that the first terminal device and the second terminal device each have a Near Field Communication (NFC) module and that the first communication channel is based on Near Field Communication (NFC). Transmitting the request message via an NFC communication channel has the advantage that the request message cannot be read by a third party, since the data transmission only takes place over a very short distance (usually a few centimeters). Therefore, it is virtually impossible for a third party to read the request message, which may, for example, contain a generated random number as a verification message, and to generate a response message based on this verification message that could then be transmitted to the first terminal device, which has been checked by a controller.

[0043] In addition, the first communication channel can be based on a Bluetooth transmission standard. This has the advantage that the verification process can be carried out over greater distances (several meters). For example, it can be provided that a control device simultaneously sends several request messages to various smartphones in the vicinity, thus allowing the simultaneous inspection of several devices or passengers. The time required for ticket inspection can thus be significantly reduced. A further advantage of using the Bluetooth transmission standard is that not all smartphones available on the market have an NFC module. Older models in particular do not have an NFC module or at least do not have a freely usable NFC module, whereas most have a Bluetooth module.

[0044] Furthermore, it can be provided that the first communication channel is designed as an optical communication channel. In particular, it can be provided that communication between the first terminal and the second terminal takes place via barcodes, in particular via 2D barcodes, which can be displayed on the screen of one terminal and read by a camera or an optical scanner of the other terminal.

[0045] According to a further embodiment of the method according to the invention, it can be provided that both the first terminal and the second terminal have a front camera. In other words, both terminals have a camera, which is arranged on the same side of each terminal as the displays of the terminals. In this way, it can be provided that, in order to verify the ticket data, both terminals are aligned head-on with each other, so that the request message can be transmitted from the second terminal to the first terminal and the response message from the first terminal to the second terminal. The corresponding data is shown on the display of each terminal (in coded or uncoded form) and read out via the camera of the other terminal.

[0046] According to a further embodiment of the method according to the invention, the NFC module of the second terminal device can also emulate an NFC tag. In other words, the control device identifies itself as an NFC tag. This has the advantage that smartphones which are not capable of communicating via the standard NFC interface, but only of reading NFC tags, can also be used in the method according to the invention. This is particularly the case with some models from the smartphone manufacturer Apple. Since the NFC interface is only partially open in various iPhone models, these models are not inherently suitable for communicating with a control device via an NFC interface. However, if the second terminal device emulates an NFC tag, communication with the aforementioned models is thereby made possible. This advantageously provides a method that can be used across platforms.

[0047] According to a further embodiment of the method according to the invention, the reply message can contain the consumer's biometric data, in particular data relating to a fingerprint, voice, facial features, or iris pattern. This has the advantage that the user's identity can be additionally verified by comparing the biometric data. Verification is performed by the second terminal device by comparing the biometric data received from the first terminal device with data from a database or directly with the user's characteristics, which are stored either on the second terminal device or in a storage element accessible via a network connection. The database can, for example, contain the fingerprint of a previously registered user as well as their full name and / or identity card number.Similarly, the voice of a previously registered user and their name or address can be stored in the database. This allows the second device to verify the identity of the person being checked by checking their biometric data.

[0048] Furthermore, it can be provided that the response message contains a photographic image of the consumer or a photographic image of the consumer's face. This has the advantage that the second terminal can subsequently verify the photographic image of the consumer received from the first terminal. According to one embodiment of the method according to the invention, it can be provided that the photographic image is first converted into a "real-life emoji image" and then only the said emoji image of the user is transmitted to the control device. In other words, an image of the user with a reduced data volume is generated and transmitted to the control device. The data volume of the emoji image is significantly reduced compared to the original photographic image. Therefore, the response message can advantageously be transmitted within a very short time.Nevertheless, the "real-life emoji image" still offers the ticket inspector a sufficiently high level of identifiability for use in public transport. When checking the electronic ticket, the ticket inspector can therefore directly verify whether the first device actually belongs to the person in possession of the device. The ticket data and a photographic image of the consumer can therefore be displayed simultaneously on the second device, allowing the ticket inspector to complete the verification in the shortest possible time.

[0049] According to a further embodiment of the method according to the invention, it can also be provided that the second terminal has a storage element and / or is connected to an external storage element on which a list of identification data is stored for which the probability of a lack of authenticity exceeds a predetermined probability threshold. The identification data can, in particular, comprise a ticket number or an identifier of a first terminal. This can further reduce the risk of individual fraudsters copying tickets. For example, it can be provided that the identification data, for example a hardware fingerprint of the inspected terminals, is recorded during each inspection. The frequency of this identification data being registered during previous inspections can then be stored in a database.If the identification data of a specific device is registered particularly frequently, this may be an indication that there are copied tickets in circulation in large numbers. For example, it may be planned that if the same identification data is registered by control devices more than ten times on a single day, the control device will issue a visual warning signal. In this case, an inspector can also request ID from the person being checked. This ensures secure yet efficient passenger screening, as an additional check of identification documents, in particular a check of the identity card or passport, is only carried out in cases where irregularities are observed. The storage element described above can be designed as an integrated memory or as a hard drive.If the storage element is embodied as an external storage element, the storage element can be configured, in particular, as a cloud storage device accessible by all controllers or control devices. The identification data can, in particular, include an ID number of the first terminal and / or biometric data. The embodiment described above can provide an effective verification method capable of efficiently detecting any possible cases of fraud.

[0050] Furthermore, according to an advantageous embodiment of the method according to the invention, the selection of the first communication channel and the second communication channel can be automated. For example, a communication channel based on the NFC standard can be automatically selected if an NFC-enabled terminal is detected in the immediate vicinity. Furthermore, a communication channel based on the Bluetooth standard can be automatically selected if no NFC-enabled terminal is detected in the vicinity of the control device, but Bluetooth-enabled devices are available instead. In an analogous manner, optical signals and acoustic signals, for example, can be used for communication between the first terminal and the control device in order to automatically select an optical or acoustic communication channel accordingly.For example, an acoustic or optical communication channel can also be used to select or communicate dynamic addresses for other wireless communication channels to be used (e.g., Bluetooth or WLAN). Furthermore, one of the end devices can generate an acoustic trigger signal that signals the other end device that communication is taking place via an acoustic signal. The acoustic trigger signal can, for example, have a specific spectrum that can be picked up and evaluated by the other end device. This provides an intelligent system that adapts to the individual environmental situation.

[0051] According to a further embodiment of the method according to the invention, it can also be provided that a trainable classifier is used for the automatic selection of communication channels. The trainable classifier can, in particular, be an artificial neural network. The classifier can be trained using historical data, which, for example, contains information about which communication channels were preferentially used in which situation.

[0052] Even though the above-described method according to the invention has been described primarily in connection with a method for verifying an electronic train ticket for practical illustration, it will be understood by those skilled in the art that the method according to the invention is not limited to methods for verifying train tickets, but that the method according to the invention is also suitable for the secure verification of all types of electronic tickets. In particular, the described method is also suitable for verifying electronic tickets for concerts, festivals, and sporting events.

[0053] Furthermore, to solve the aforementioned problem, a control device for verifying an electronic ticket, in particular an electronic bus and / or train ticket, is proposed according to the independent device claim. The electronic ticket is stored on a first mobile device assigned to an end user. The control device according to the invention comprises at least one processor, one memory, and one communication module and is designed to to send a request message to the first terminal via a first communication channel; to receive a response message from the first terminal via a second communication channel, wherein the response message is signed by the first terminal and wherein the second communication channel is either identical to the first communication channel or different from the first communication channel; to verify the signed response message; and to confirm the authenticity of the response message, provided that the authenticity of the signature could previously be confirmed by the control device.

[0054] According to one embodiment of the control device according to the invention, the communication module may include an NFC module, a Bluetooth module, a camera and / or a display.

[0055] It is taken for granted by those skilled in the art that all features described in connection with the method according to the invention can also be combined with the control device according to the invention.

[0056] The present invention provides a multi-stage process, including a trust anchor, a trusted client application, a ticket issuing system, a control device, and a revocation service. Each of the individual components of the present invention contributes to overall increased security, significantly complicating potential misuse of the provided ticket system compared to previously known systems.

[0057] The invention is explained in more detail below with reference to exemplary embodiments and the drawings. Specifically, the drawings show: Fig. 1 shows a schematic representation of a unidirectional ticket verification method according to the prior art, Fig. 2 shows a schematic representation of an embodiment of the bidirectional ticket verification method according to the invention, Fig. 3 shows a further schematic representation of an embodiment of the method according to the invention, wherein a request message A and a response message B are exchanged between a control device and a mobile terminal, Fig. 4 shows a further schematic representation of an embodiment of the method according to the invention, wherein a control device and a mobile terminal additionally communicate with a server, Fig. 5 shows a further schematic representation of an embodiment of the method according to the invention, wherein the response message contains a digital certificate, Fig.Fig. 6 a schematic representation of an embodiment of the method according to the invention, wherein the response message includes a timestamp; Fig. 7 a further schematic representation of an embodiment of the method according to the invention, wherein the server determines an identifier assigned to the mobile device and creates a digital certificate containing the identifier; Fig. 8 a flowchart describing an embodiment of the method according to the invention; and Fig. 9 a further flowchart describing another embodiment of the method according to the invention, wherein the request message includes a verification message.

[0058] In the Fig. 1A schematic representation of a ticket verification method according to the prior art is shown. In the method shown, unidirectional communication takes place between a first mobile terminal 10, which is assigned to a consumer, and a second terminal 12, which is assigned to an inspector. In the illustrated embodiment, the first mobile terminal is embodied as a smartphone. The second terminal 12, which in the context of the present invention is also referred to as a checking device, is embodied as a mobile terminal in the illustrated example. The first mobile terminal 10 and the checking device 12 each have a display element 14, 16. The ticket data 18 is displayed in text form on the display element 14 of the first terminal 10. The ticket data 18 can, in particular, contain information about the route, the booked class (1st class or 2nd class), or a seat reservation.Furthermore, the ticket data is displayed in encrypted form using a 2D barcode 20 on the display element 14 of the first terminal device 10. The first terminal device 10 sends the ticket data to the control device 12 via a communication channel 24. The communication channel 24 can be implemented as an optical communication channel. Thus, the control device 12 can be equipped with a camera or a barcode scanner (both in the ). Fig. 1The ticket data stored on the first terminal 10 (not shown) can be read. The ticket data is then evaluated and verified. For example, the booked route can be compared with the actual route to check whether the passenger is on the correct train. If the ticket data is correct and the passenger has a valid authorization to use the selected means of transport, a confirmation message can be displayed on the display element 16 of the second terminal 12. This lets the ticket inspector know that the passenger has a valid ticket.

[0059] In the Fig. 21 shows a schematic representation of an exemplary embodiment of the method according to the invention, in which communication between the control device 12 and the terminal 10 takes place bidirectionally. The control device 12 can send data to the first terminal 10 via a first communication channel 22. The first terminal 10 can send data to the control device 12 via a second communication channel 24. The two communication channels 22, 24 can be identical. For example, both communication channels can be based on the NFC transmission standard. It can also be provided that the first communication channel 22 is based on the NFC transmission standard and the second communication channel 24 is implemented as an optical communication channel. In this way, the request message A can be sent via an NFC communication channel, while the response message B is represented as a barcode and optically read out by the control device 12.Bidirectional communication during ticket verification can increase security, as shown in the following figures.

[0060] In the Fig. 3A specific embodiment of the method according to the invention is shown, wherein both the control device 12 and the first mobile terminal 10 are designed as smartphones. According to the method shown, the control device 12 first sends a request message A to the first terminal 10 via the first communication channel 22. The first terminal 10 then sends a response message B to the control device 12 via the second communication channel 24. The response message B is signed by the first terminal 10. Using the signature of the response message B, the control device 12 can verify whether the response message B was actually created by the first terminal 10 or whether the content of the response message B has possibly been manipulated. The signature of the response message B by the first terminal 10 is carried out using a private key of the first terminal 10.When verifying the reply message B, a public key from the first terminal 10 is used to check the authenticity of the reply message B. This public key can, for example, be pre-stored on the control device 12. Alternatively, the reply message B can contain the public key. If the signature of the reply message B could be verified by the control device 12 and the ticket data is also correct, a confirmation message can be displayed on the display element 16 of the control device 12.

[0061] Furthermore, in the Fig. 4a further exemplary embodiment of the method according to the invention is shown, in which the first terminal 10 and the control device 12 communicate with a server 26. In this exemplary embodiment, it can be provided in particular that the public key 28 of the first terminal 10 is stored on a server 26 via a third communication channel 30. This can occur, for example, when a consumer registers with a transport company. In this case, all public keys of each consumer are stored on the server 26. During ticket inspection, the control device 12 can then access the server 26 and the public key 28 of the first mobile terminal 10 stored thereon via a fourth communication channel 31. The control device 12 can then verify the signature of the response message B using the public key 28.If this could be verified and the ticket data is also correct, a confirmation message can be displayed on the display element 16 of the second terminal 12.

[0062] In the Fig. 5a further schematic representation of an embodiment of the method according to the invention is shown. In this embodiment, the control device 12 sends the request message A to the first terminal 10 via the first communication channel 22. The first terminal 10 then sends a response message B to the control device 12. The response message B contains a digital certificate 32. The digital certificate 32 can, in particular, be a public-key certificate. The digital certificate 32 can contain information about the issuer of the certificate (for example, their name), the consumer (for example, their name, date of birth, and address), the consumer's terminal (for example, the ID of the terminal), or the validity period of the certificate (for example, 3 months).The digital certificate can also contain the public key 28 of the first terminal device 10 or the public key of the certificate issuer. Furthermore, the digital certificate 32 can contain a digital signature of the issuer.

[0063] In the Fig. 6A further embodiment of the method according to the invention is shown, wherein in this embodiment the response message B has a timestamp. The timestamp documents when the response message B was generated. The control device 12 can thus, for example, check whether the response message B was generated after the control device 12 sent a request message A to the first terminal 10, or whether the response message B was already generated before the control device 12 sent the request message A to the terminal 10. If the response message B was already generated before the request message A was transmitted to the first terminal, it can be assumed that the authenticity of the ticket is at least doubtful.In this case, a corresponding notification may appear on the display element 16 of the second terminal 12, recommending that the ticket inspector manually check the passenger's ID data in addition to the verification method according to the invention. A significant advantage of the method according to the invention is that this - more time-consuming - verification of the ID data only needs to be performed if anomalies are observed during the ticket verification method according to the invention. Fig. 6In the embodiment shown, it can alternatively be provided that the time stamp 34 is compared with the current time, and the electronic ticket is classified as invalid if the time stamp is older than a predetermined period of time (e.g., 1 minute or 5 minutes). Thus, if the response message B was generated 2 hours ago, this can be interpreted as an indication that the response message B or the electronic ticket is invalid. In this case, the passenger's ID data can also be checked manually.

[0064] A further preferred embodiment of the method according to the invention is described in Fig. 7shown. In this embodiment, the response message B contains a digital certificate 32. The digital certificate 32 was previously generated by the server 26. The generation of the digital certificate 32 can occur, for example, when the user registers with the transport company. During registration, the server 26 determines a unique identifier 36 of the first terminal 10. This identifier 36 can be, for example, a hardware fingerprint. As already explained above, this can be determined, for example, via the serial number of a hardware component, in particular a processor or a RAM, of the first terminal 10. In other words, the first terminal 10 can transmit an identifier 36 to the server 26 upon registration with the transport company. Alternatively, the server can read out the identifier of the first terminal 10.The server 26 then generates a digital certificate 32 containing the identifier 36 of the first terminal device 10. The identifier 36 uniquely identifies the first terminal device 10 during the subsequent ticket verification process. The digital certificate 32 is preferably digitally signed. Communication between the first terminal device 10 and the server 26 takes place via a third communication channel 30. When the control device 12 verifies the electronic ticket, the response message B and the digital certificate 32 it contains can be checked. The identifier of the first terminal device 10 is also read during the verification of the electronic ticket, as was previously done by the server 20.If the control device 12 comes to the conclusion that the identifier of the first terminal device 10 differs from the identifier stored in the digital certificate 32, this can be interpreted as an indication that the electronic ticket is invalid or that the passenger does not have a valid authorization to use the means of transport. In this case, a notification can be displayed on the display element 16 of the control device 12, advising the inspector to manually check the passenger's ID data. Alternatively, it can be provided that the ID stored in the digital certificate is compared with the ID stored in the electronic ticket. In this case, a deviation between the ID in the digital certificate and the ID stored in the ticket can be interpreted as an indication that the electronic ticket is invalid orthat the passenger does not have a valid authorization to use the selected means of transport. In principle, there are three different options for verifying the ID (comparison of the ID stored in the ticket with the ID stored in the digital certificate, comparison of the ID stored in the ticket with the ID read out by the first terminal device, comparison of the ID stored in the digital certificate with the ID read out by the first terminal device). In the illustrated embodiment of the method according to the invention, it can optionally be provided that the control device 12 communicates with the server 26 via a fourth communication channel 31. This can be used, for example, to query the public key of the server 26 or of the first terminal device 10. Alternatively, it can also be provided that the aforementioned keys are stored in the control device 12 by default.

[0065] In the Fig. 8The individual steps of an embodiment of the method according to the invention are shown. In response to a request message A from the control device 12 (second terminal), the first terminal 10 generates a signed response message B. By verifying the signature contained in the response message B, the control device 12 can check whether the response message B was actually generated by the first terminal 10 and is authentic, or whether the signature was generated by another device or the content of the response message B has been manipulated (principle of identity and integrity verification). For signature verification, the control device requires the public key 28 of the first terminal 10. This public key 28 can optionally be included in the response message B. Alternatively, it can also be provided that this public key 28 is stored on a server that the control device 12 can access.

[0066] Finally, in the Fig. 9The individual steps of a further embodiment of the method according to the invention are illustrated. In this embodiment, the request message B, which is sent from the control device 12 to the first terminal device 10, contains a verification message. The verification message can, in particular, be a text message or a sequence of numbers generated by the control device 12. In particular, it can be a particularly long random number generated by the control device 12. The first terminal device 10 receives this verification message and integrates it into the response message B, which is then signed by the first terminal device 10. The first terminal device 10 then sends the signed response message B, which contains the verification message, to the control device 12.The control device 12 can thus verify whether the first terminal 10 has actually received the verification message and also whether it has a corresponding private key for generating a digital signature. This virtually eliminates the possibility that the first terminal 10 will send a response message B that was previously generated by a third party, since a third party cannot know which verification message is generated by the control device 12 and sent to the first terminal 10. The method described in the . Fig. 9 The embodiment of the method according to the invention shown here therefore ensures a particularly high level of security when verifying electronic tickets. List of reference symbols

[0067] 10First terminal 12Second terminal 14Display element of the first terminal 16Display element of the second terminal 18Ticket data in text form 20Barcode with ticket data 22First communication channel 24Second communication channel 26Server 28Public key 30Third communication channel 31Fourth communication channel 32Digital certificate 34Time stamp 36Identifier S100Inventive method according to a first embodiment S110First method step according to the first embodiment S120Second method step according to the first embodiment S130Third method step according to the first embodiment S140Fourth method step according to the first embodiment S200Inventive method according to a second embodiment S210First method step according to the second embodiment S220Second method step according to the second embodiment S230Third method step according to the second embodiment S240FourthMethod step according to the second embodiment ARequest message BResponse message

Claims

1. A method for securely checking an electronic ticket, in particular an electronic bus and / or railway ticket, wherein the electronic ticket is stored on a first mobile terminal device (10) allocated to an end consumer, and the ticket is checked using a second terminal device (12) allocated to a ticket inspector or to a control system, wherein the method comprises the following steps: - sending a request message (A) from the second terminal device (12) to the first terminal device (10) via a first communication channel (22); - sending a response message (B) from the first terminal device (10) to the second terminal device (12) via a second communication channel (24), the response message (B) being signed by the first terminal device (10), and the second communication channel (24) either being identical with the first communication channel (22) or different from the first communication channel (22); - verifying the signed response message (B) by the second terminal device (12); and - confirming the authenticity of the response message (B) by the second terminal device (12), if the second terminal device (12) was previously able to verify the authenticity of the signature; wherein - the request message (A) comprises a random number of the length L, generated by the second terminal device (12), where L >=1, and the response message (B) includes a representation of the random number generated by the second terminal device (12), encrypted using a private key of the first terminal device (10); - the response message (B) includes a digital certificate (32) that originates from the service provider that has issued the electronic ticket or from an entity classified as trustworthy by the service provider; - the response message (B) comprises an electronic ticket which, besides the ticket information, also comprises a first digital identifier of the first terminal device (10), and that the electronic ticket comprises a digital signature of the service provider; - in addition to the electronic ticket, the response message (B) comprises a second digital identifier of the first terminal device (10) generated by the first terminal device (10); and - the second terminal device (12) confirms the authenticity of the response message (B) only if the first identifier contained in the electronic ticket and the second identifier generated by the first terminal device (10) are identical.

2. The method according to claim 1, characterized in that the response message (B) comprises a time stamp (34), and that the authenticity of the response message (B) is confirmed by the control device only if the age of the time stamp (34) is below a predetermined threshold value.

3. The method according to claim 1, characterized in that the response message (B) contains a digital certificate (32) in which a security indicator is stored which characterizes the fulfillment of predetermined security requirements by the first terminal device.

4. The method according to claim 3, characterized in that the security indicator is implemented as a binary security flag, which - has a value of 1, if a previous security check of the first terminal device (10) has shown that the first terminal device (10) fulfills the predetermined security requirements, and - has a value of 0, if the previous security check of the first terminal device (10) has shown that the first terminal device (10) does not fulfill the predetermined security requirements.

5. The method according to one of claims 1 to 4, characterized in that the first terminal device (10) and the second terminal device (12) each comprise a near field communication module (NFC module), and that the first communication channel (22) is based on near field communication (NFC).

6. The method according to one of claims 1 to 5, characterized in that the NFC module of the second terminal device (12) emulates an NFC tag.

7. The method according to any one of claims 1 to 6, characterized in that the second communication channel (24) is based on Near Field Communication, NFC.

8. The method according to any one of claims 1 to 7, characterized in that the response message (B) contains biometrical data of the consumer, in particular data related to a fingerprint, a voice, features of a face or a pattern of an iris.

9. The method according to any one of claims 1 to 8, characterized in that the response message (B) comprises a photographic image of the consumer or a photographic image of the consumer's face.

10. The method according to any one of claims 1 to 9, characterized in that the second terminal (12) comprises a memory element and / or is connected with an external memory element which stores a list of identification data for which the probability of a lack in authenticity exceeds a predetermined probability threshold.

11. The method according to any one of claims 1 to 10, characterized in that the selection of the first communication channel (22) and the second communication channel (24) is automated.

12. The method according to any one of claims 1 to 11, characterized in that the response message (B) includes information about a digital fingerprint of the first terminal device (10).

13. A control device for checking an electronic ticket, in particular an electronic bus and / or railway ticket, wherein the electronic ticket is stored on a first mobile terminal device (10) associated with an end consumer, comprising at least a processor, a memory and a communication module, the control device being configured to - send a request message (A) to the first terminal device (10) via a first communication channel (22); - receive a response message (B) from the first terminal device (10) via a second communication channel (24), the response message (B) being signed by the first terminal device (10), and the second communication channel either being identical with the first communication channel or different from the first communication channel (22); - verify the signed response message (B); and - confirm the authenticity of the response message (B) if the authenticity of the signature could be confirmed by the control device before; wherein - the request message (A) comprises a random number of the length L, generated by the second terminal device (12), where L >=1, and the response message (B) includes a representation of the random number generated by the second terminal device (12), encrypted using a private key of the first terminal device (10); - the response message (B) includes a digital certificate (32) that originates from the service provider that has issued the electronic ticket or from an entity classified as trustworthy by the service provider; - the response message (B) comprises an electronic ticket which, besides the ticket information, also comprises a first digital identifier of the first terminal device (10), and that the electronic ticket comprises a digital signature of the service provider; - in addition to the electronic ticket, the response message (B) comprises a second digital identifier of the first terminal device (10) generated by the first terminal device (10); and - the second terminal device (12) confirms the authenticity of the response message (B) only if the first identifier contained in the electronic ticket and the second identifier generated by the first terminal device (10) are identical.

14. The control device according to claim 13, characterized in that the communication module comprises an NFC module, a Bluetooth module, a camera and / or a display.