Distributed cross-domain data encryption method, decryption method and system

Abstract

The present invention discloses a distributed cross-domain data encryption method, decryption method and system. The encryption method comprises: a first key calculation node calculates a first point on an elliptic curve and sends a parameter to a second key calculation node; the second key calculation node calculates a second point on the elliptic curve and sends a parameter to the first key calculation node; the first key calculation node calculates a third point on the elliptic curve; the first key calculation node calculates a first symmetric encryption key; the first key calculation node encrypts plaintext data and generates ciphertext data. By using the present invention, there is no need to pre-share a master key between different service domains, which completely solves the problem that the risk of master key exposure increases as the system service scope increases.

Description

Technical Field

[0001] The present invention relates to a distributed cross-domain data encryption method, and also relates to a corresponding distributed cross-domain data decryption method and a distributed cryptographic computing system for implementing the above method, belonging to the field of confidential communication technology. Background Art

[0002] In the application scenario of confidential communication, the security of data transmission is guaranteed by the encryption and decryption process. Specifically, the data is first encrypted using an encryption key and an encryption algorithm at the sender. The encrypted data, or ciphertext, is then sent through the transmission channel and decrypted using a decryption key and a decryption algorithm at the receiver to restore the original plaintext data. This process ensures the confidentiality of the data during transmission.

[0003] In the above data transmission process, there are mainly two commonly used encryption schemes: pre-shared master key scheme and digital envelope scheme.

[0004] The pre-shared master key scheme works as follows: the sender uses a master key that is pre-shared with the receiver, combined with a key derivation function (KDF) and the data tag (ID) of the plaintext data to generate a symmetric key (K) for encryption. Then, the sender uses this symmetric key and a symmetric encryption algorithm to encrypt the plaintext information to generate a ciphertext (C). During the transmission process, the sender sends the data tag (ID) of the plaintext data and the ciphertext (C) to the receiver. After receiving this information, the receiver uses the same master key, key derivation function (KDF) and data tag (ID) to restore the symmetric key (K), and uses this key to decrypt the ciphertext to obtain the original plaintext data. However, the pre-shared master key scheme has some disadvantages. First, as the service scope of the system expands, the number of master keys that need to be shared increases, which increases the risk of master keys being leaked. Second, since all receivers hold the same master key, it is impossible to restrict only specific receivers to decrypt the data, which reduces the ability to ensure the confidentiality of the data.

[0005] The operation of the digital envelope scheme relies on the public key infrastructure (PKI) system. In this scheme, the sender needs to obtain the public key certificate of the receiver in advance. The sender uses the receiver's public key to encrypt the symmetric key to form a digital envelope, and then sends the digital envelope and ciphertext to the receiver. The receiver uses his own private key to decrypt the digital envelope, obtain the symmetric key, and then uses the symmetric key to decrypt the ciphertext and restore the plaintext data. The main disadvantage of the digital envelope scheme is its reliance on the public key infrastructure (PKI) system. This means that it is necessary to build or rent a PKI service in advance to complete the issuance of certificates. In addition, the sender also needs to obtain and store the receiver's certificate in advance, or rely on an external certificate query system, which increases the complexity and operating costs of the system. Summary of the invention

[0006] The primary technical problem to be solved by the present invention is to provide a distributed cross-domain data encryption method.

[0007] Another technical problem to be solved by the present invention is to provide a distributed cross-domain data decryption method.

[0008] Another technical problem to be solved by the present invention is to provide a distributed cryptographic computing system for implementing the above method.

[0009] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0010] According to a first aspect of an embodiment of the present invention, a distributed cross-domain data encryption method is provided, comprising the following steps:

[0011] S11: The first key calculation node calculates the first point on the elliptic curve and sends parameters to the second key calculation node;

[0012] S12: The second key calculation node calculates a second point on the elliptic curve and sends a parameter to the first key calculation node;

[0013] S13: The first key calculation node calculates the third point on the elliptic curve;

[0014] S14: The first key calculation node calculates a first symmetric encryption key;

[0015] The calculation formula is:

[0016] =

[0017] in, is the third point on the elliptic curve The vertical coordinate value of , and it is a large integer;

[0018] S15: The first key calculation node encrypts the plaintext data to generate ciphertext data.

[0019] Preferably, the first key calculation node calculates the first point on the elliptic curve, including the following sub-steps:

[0020] S111: Mapping the data identifier to a point on the elliptic curve;

[0021] The mapping formula is:

[0022] =

[0023] Where G is the generator of the elliptic curve cyclic group of the selected prime order, For G Double point;

[0024] S112: The first key calculation node generates a first random large integer;

[0025] S113: The first key calculation node calculates the first point on the elliptic curve;

[0026] The calculation formula is:

[0027] =

[0028] in, When the system is initialized, the first key is calculated as the root key of the node, and ; a first random large integer generated by the first key computation node, and

[0029] S114: The first key calculation node sends { , }.

[0030] Preferably, the second key calculation node calculates the second point on the elliptic curve, comprising the following sub-steps:

[0031] S121: The second key calculation node calculates the key according to { , }Calculate the second point on the elliptic curve;

[0032] The calculation formula is:

[0033] =

[0034] in, The root key of the second key calculation node when the system is initialized;

[0035] S122: The second key calculation node sends a request to the first key calculation node send{ , }.

[0036] Preferably, the first key calculation node calculates the third point on the elliptic curve, comprising the following sub-steps:

[0037] S131: The first key calculation node calculates the multiplication inverse of the first random large integer on the set of positive integer prime numbers;

[0038] S132: The first key calculation node calculates the key according to { , }Calculate the third point on the elliptic curve;

[0039] The calculation formula is:

[0040] = .

[0041] According to a second aspect of an embodiment of the present invention, a distributed cross-domain data decryption method is provided, comprising the following steps:

[0042] S21: The second key calculation node calculates the fourth point on the elliptic curve and sends the parameter to the first key calculation node;

[0043] S22: The first key calculation node calculates the fifth point on the elliptic curve, and sends the parameter to the second key calculation node;

[0044] S23: The second key calculation node calculates the sixth point on the elliptic curve;

[0045] S24: The second key calculation node calculates a second symmetric encryption key; the calculation formula is:

[0046] =

[0047] in, is the sixth point on the elliptic curve The vertical coordinate value of , and it is a large integer;

[0048] S25: The second key calculation node decrypts the ciphertext data to obtain plaintext data.

[0049] Preferably, the second key calculation node calculates the fourth point on the elliptic curve, including the following sub-steps:

[0050] S211: Map the data identifier to a point on the elliptic curve;

[0051] The mapping formula is:

[0052] =

[0053] Where G is the generator of the elliptic curve cyclic group of the selected prime order, For G Double point;

[0054] S212: The second key calculation node generates a second random large integer;

[0055] S213: The second key calculation node calculates the fourth point on the elliptic curve;

[0056] The calculation formula is:

[0057] =

[0058] in, The root key of the second key calculation node when the system is initialized; is the second largest random integer, and ;

[0059] S214: The second key calculation node sends a request to the first key calculation node send{ , }.

[0060] Preferably, the first key calculation node calculates the fifth point on the elliptic curve, comprising the following sub-steps:

[0061] S221: The first key calculation node calculates the key according to { , }, calculate the fifth point on the elliptic curve; the calculation formula is:

[0062] =

[0063] S222: The first key calculation node sends { , }.

[0064] Preferably, the second key calculation node calculates the sixth point on the elliptic curve, comprising the following sub-steps:

[0065] S231: The second key calculation node calculates the multiplication inverse of the second random large integer on the positive integer prime number set;

[0066] S232: Second key calculation node according to{ , }Calculate the sixth point on the elliptic curve ; The calculation formula is:

[0067] = .

[0068] According to a third aspect of an embodiment of the present invention, a distributed cryptographic computing system is provided, comprising a plurality of service domains and a plurality of key computing nodes, each key computing node corresponding to a service domain; wherein,

[0069] The encrypting party encrypts the data to be encrypted according to any of the above-mentioned distributed cross-domain data encryption methods through the key computing node of the service domain where the encrypting party is located;

[0070] After the data encryption is completed, the encrypting party sends the encrypted data to the decrypting party;

[0071] After receiving the encrypted data, the decryption party decrypts the data through the key computing node of the service domain where the decryption party is located according to any of the distributed cross-domain data decryption methods described above to obtain the plaintext data.

[0072] Compared with the prior art, the present invention first solves the problem of data confidentiality across service domains. Through the distributed cryptographic computing architecture, there is no need to pre-share master keys between different service domains, thereby completely eliminating the problem that the risk of master key exposure increases as the system service scope increases. Secondly, the present invention enhances the ability to ensure data confidentiality. The data sender can limit the data to only the data receiver in a specific service domain, ensuring the security of the data. In addition, the present invention does not need to rely on the public key infrastructure (PKI) system, reducing the complexity of the system's business functions, while also eliminating the need to pre-store recipient certificates or rely on external certificate query systems, further reducing the complexity of storage functions. In general, the present invention provides a secure, efficient and easy-to-manage cross-domain data encryption and decryption method through its innovative technical solution, which is particularly suitable for a variety of data transmission scenarios that require high security. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 A schematic diagram of the structure of a distributed cryptographic computing system provided by an embodiment of the present invention;

[0074] Figure 2 A flow chart of a distributed cross-domain data encryption method provided by an embodiment of the present invention;

[0075] Figure 3 A schematic diagram of generating a first symmetric encryption key by using a key derivation function in an embodiment of the present invention;

[0076] Figure 4 A schematic diagram of a plaintext encryption process in an embodiment of the present invention;

[0077] Figure 5 A flowchart of a distributed cross-domain data decryption method provided by an embodiment of the present invention;

[0078] Figure 6 A schematic diagram of generating a second symmetric encryption key by using a key derivation function in an embodiment of the present invention;

[0079] Figure 7 The figure is a schematic diagram of the ciphertext decryption process in an embodiment of the present invention. DETAILED DESCRIPTION

[0080] The technical content of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0081] First embodiment

[0082] like Figure 1 As shown, the first embodiment of the present invention provides a distributed cryptographic computing system. The system includes multiple key computing nodes and multiple service domains, wherein each key computing node corresponds to a service domain and is responsible for key computing work within the service domain. Figure 1 In the first embodiment shown, four key calculation nodes and four service domains are included. However, in actual deployment, any number of key calculation nodes can be set up according to the required number of service domains, not limited to Figure 1 4 are shown in the figure.

[0083] In this distributed cryptographic computing system, the user first sends the plaintext data to the key computing node of the service domain to which he belongs. The node will encrypt the data according to the user's specific needs and generate ciphertext data. Then, the encrypted ciphertext data is sent to another key computing node in the target service domain. After receiving the ciphertext data, the key computing node in the target service domain will perform a decryption operation. Once the decryption is completed, the obtained plaintext data will be securely presented to the user, thereby realizing the secure transmission and sharing of data between different service domains.

[0084] Below, the process of how the above-mentioned distributed cryptographic computing system implements distributed cross-domain data encryption and decryption is described in detail through different embodiments.

[0085] Second embodiment

[0086] In one embodiment of the present invention, it is necessary to convert the plaintext data , Data Identification , decryption verification password Pwd and data decryption service domain identifier j, forming the first four-tuple {plaintext data , Data Identification , decryption verification password Pwd, data decryption service domain identifier j} are sent to the first key calculation node , to encrypt data.

[0087] like Figure 2 As shown, a distributed cross-domain data encryption method provided by the second embodiment of the present invention at least includes the following steps:

[0088] S11: First key calculation node Compute the first point on the elliptic curve , and to the second key calculation node Send parameters.

[0089] S12: Second key calculation node Compute the second point on the elliptic curve , and to the first key calculation node Send parameters.

[0090] S13: First key calculation node Compute the third point on the elliptic curve .

[0091] S14: First key calculation node Calculate the first symmetric encryption key .

[0092] like Figure 3 As shown, the first key calculation node , using key derivation functions (KDF) to identify data and the third point on the elliptic curve The ordinate value is calculated to obtain the first symmetric encryption key .

[0093] The corresponding calculation formula is:

[0094] =

[0095] in, is the third point on the elliptic curve The vertical coordinate value is a large integer. The large integer here refers to the integer that exceeds the range of the standard data type. Their size exceeds the range that can be represented by the regular integer type (such as int or long).

[0096] S15: First key calculation node Encrypting plaintext data , generate ciphertext data .

[0097] like Figure 4 As shown, the first key calculation node Using a symmetric encryption algorithm and a first symmetric encryption key , encrypt plaintext data , generate ciphertext data .

[0098] In one embodiment of the present invention, the first key calculation node in step S11 Compute the first point on the elliptic curve The method comprises the following sub-steps:

[0099] S111: Data identification Mapped to points on the elliptic curve .

[0100] The corresponding mapping formula is:

[0101] =

[0102] Where G is the selected prime order The generator of the elliptic curve cyclic group E, For G Double the points.

[0103] S112: First key calculation node Generate the first random large integer .

[0104] S113: First key calculation node Compute the first point on the elliptic curve .

[0105] The corresponding calculation formula is:

[0106] =

[0107] in, When the system is initialized, the first key calculation node The root key of .

[0108] S114: First key calculation node To the second key calculation node send{ , }.

[0109] Next, the second key calculation node in step S12 Compute the second point on the elliptic curve The method comprises the following sub-steps:

[0110] S121: Second key calculation node according to{ , }Calculate the second point on the elliptic curve .

[0111] The corresponding calculation formula is:

[0112] =

[0113] Right now:

[0114] =

[0115] in, When the system is initialized, the second key calculation node The root key.

[0116] S122: Second key calculation node To the first key calculation node send{ , }.

[0117] Next, the method for the first key calculation node in step S13 to calculate the third point on the elliptic curve includes the following sub-steps:

[0118] S131: First key calculation node Calculate the first random large integer exist The multiplicative inverse of .

[0119] because is a prime number, so must exist, and .

[0120] S132: First key calculation node according to{ , }Calculate the third point on the elliptic curve .

[0121] The corresponding calculation formula is:

[0122] =

[0123] Right now:

[0124] =

[0125] It should be noted that the calculation in the embodiment of the present invention is based on the elliptic curve finite group and the prime order cyclic group. The generator of the elliptic curve cyclic group E is G, the set of positive integer primes In the calculation process, the , and , which are typical secure hash algorithms.

[0126] In a preferred embodiment of the present invention, the above-mentioned secure hash algorithm can be replaced by China Commercial Cryptography Algorithm No. 3 (SM3), and the symmetric encryption algorithm includes but is not limited to China Commercial Cryptography Algorithm No. 4 (SM4).

[0127] Third embodiment

[0128] In one embodiment of the present invention, the data encryption party encrypts the ciphertext data , Data Identification , decrypt the verification password Pwd and generate ciphertext data The service domain identifier i, forming the second four-tuple {ciphertext data , Data Identification , decrypt verification password Pwd, generate ciphertext data The data decryption party sends the second quaternary {ciphertext data , Data Identification , decrypt verification password Pwd, generate ciphertext data The service domain identifier i} is sent to the second key calculation node , to decrypt the data.

[0129] like Figure 5 As shown, a distributed cross-domain data decryption method provided by the second embodiment of the present invention at least includes the following steps:

[0130] S21: Second key calculation node Compute the fourth point on the elliptic curve , and to the first key calculation node Send parameters.

[0131] S22: First key calculation node Compute the fifth point on the elliptic curve , and to the second key calculation node Send parameters.

[0132] S23: Second key calculation node Compute the sixth point on the elliptic curve .

[0133] S24: Second key calculation node Calculate the second symmetric encryption key .

[0134] like Figure 6 As shown, the second key calculation node , using the key derivation function to identify the data and the sixth point on the elliptic curve The ordinate value is calculated to obtain the second symmetric encryption key .

[0135] The corresponding calculation formula is:

[0136] =

[0137] in, is the sixth point on the elliptic curve The vertical coordinate value of , which must be a large integer.

[0138] It can be seen that due to the sixth point on the elliptic curve The value of the third point on the elliptic curve The value of is equal to the vertical coordinate value of the sixth point on the elliptic curve The ordinate value of the third point on the elliptic curve are also equal, so the second symmetric encryption key With the first symmetric encryption key equal, that is, the second key computing node in the decryption service domain j After calculation, the first symmetric encryption key generated in the encryption service domain i is restored, and the second symmetric encryption key can be used to complete data decryption.

[0139] S25: Second key calculation node Decrypting ciphertext data , get the plaintext data .

[0140] like Figure 7 As shown, the second key calculation node , using a symmetric encryption algorithm and a second symmetric encryption key , decrypt the ciphertext data , get the plaintext data Among them, the symmetric encryption algorithm includes but is not limited to China Commercial Encryption Algorithm No. 4.

[0141] In one embodiment of the present invention, in step S21, the second key calculation node calculates the fourth point on the elliptic curve The method comprises the following sub-steps:

[0142] S211: Data identification Mapped to points on the elliptic curve .

[0143] The corresponding mapping formula is:

[0144] =

[0145] Among them, G is the generator of the selected elliptic curve cyclic group E, For G Double the points.

[0146] S212: Second key calculation node Generate a second random large integer .

[0147] S213: Second key calculation node Compute the fourth point on the elliptic curve .

[0148] The corresponding calculation formula is:

[0149] =

[0150] in, When the system is initialized, the second key calculation node The root key.

[0151] S214: Second key calculation node To the first key calculation node send{ , }.

[0152] Next, the method in step S22 for the first key calculation node to calculate the fifth point on the elliptic curve includes the following sub-steps:

[0153] S221: First key calculation node according to{ , }, calculate the fifth point on the elliptic curve .

[0154] The corresponding calculation formula is:

[0155] =

[0156] Right now:

[0157] =

[0158] S222: First key calculation node To the second key calculation node ,send{ , }.

[0159] Next, in step S23, the second key calculation node Compute the sixth point on the elliptic curve , including the following sub-steps:

[0160] S231: Second key calculation node Calculate the second largest random integer exist The multiplicative inverse of .

[0161] because is a prime number, so must exist, and .

[0162] S232: Second key calculation node according to{ , }Calculate the sixth point on the elliptic curve .

[0163] The corresponding calculation formula is:

[0164] =

[0165] Right now:

[0166] =

[0167] From this we can see that the sixth point on the elliptic curve The value of the third point on the elliptic curve The value of is equal to that of the second key calculation node in the decryption service domain j. After calculation, the third point on the elliptic curve generated in the encryption service domain i is restored .

[0168] It should be noted that the above embodiments are only examples, and the technical solutions of the various embodiments can be combined, all within the protection scope of the present invention.

[0169] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0170] The above is a detailed description of the distributed cross-domain data encryption method, decryption method and system provided by the present invention. For those skilled in the art, any obvious changes made to it without departing from the essence of the present invention will constitute an infringement of the patent right of the present invention and will bear corresponding legal responsibilities.

Claims

1. A distributed cross-domain data encryption method, characterized in that At least the following steps are included: S11: The first key calculation node calculates the first point on the elliptic curve and sends parameters to the second key calculation node; S12: The second key calculation node calculates a second point on the elliptic curve and sends a parameter to the first key calculation node; S13: The first key calculation node calculates the third point on the elliptic curve; S14: The first key calculation node calculates the first symmetric encryption key K i→j ; The calculation formula is: K i→j =KDF([T i→j ],id) Where KDF is the key derivation function; [T i→j ] is the third point T on the elliptic curve i→j The vertical coordinate value of is a large integer; id is the data identifier; S15: The first key calculation node encrypts the plaintext data to generate ciphertext data; The method for the first key calculation node to calculate the first point on the elliptic curve comprises the following sub-steps S111: Mapping the data identifier to a point on the elliptic curve; The mapping formula is: id =H C (id)·G Where G is the generator of the elliptic curve cyclic group of the selected prime order, P id H for G C (id) times point; It is a typical secure hash algorithm; S112: The first key calculation node generates a first random large integer; S113: The first key calculation node calculates the first point on the elliptic curve; The calculation formula is: F i→j =R i ·K i ·(K i +H ɑ (id))·P id Among them, F i→j is the first point on the elliptic curve; K i The root key of the first key calculation node when the system is initialized, and R i a first random large integer generated by the first key computation node, and It is a typical secure hash algorithm; S114: The first key calculation node sends {F i→j ,id}; The method for the second key calculation node to calculate the second point on the elliptic curve comprises the following sub-steps: S121: The second key calculation node calculates the key according to {F i→j ,id} calculate the second point on the elliptic curve; The calculation formula is: S i→j =R i ·K i ·K j ·(K i +H ɑ (id)).(K j +H ɑ (id)).P id Among them, S i→j is the second point on the elliptic curve; K j The root key of the second key calculation node when the system is initialized; S122: The second key calculation node sends a message to the first key calculation node N i Send i→j ,id}; The method for the first key calculation node to calculate the third point on the elliptic curve comprises the following sub-steps: S131: The first key calculation node calculates the multiplication inverse of the first random large integer on the set of positive integer prime numbers; S132: The first key calculation node calculates the key according to {S i→j ,id} calculate the third point on the elliptic curve; The calculation formula is: T i→j =K i K j ·(K i +H ɑ (id)).(K j +H ɑ (id))·P id +H b (pwd)·G Among them, T i→j is the third point on the elliptic curve; It is a typical secure hash algorithm; pwd is the decryption verification password.

2. A distributed cross-domain data decryption method, characterized in that At least the following steps are included: S21: The second key calculation node calculates the fourth point on the elliptic curve and sends the parameter to the first key calculation node; S22: The first key calculation node calculates the fifth point on the elliptic curve, and sends the parameter to the second key calculation node; S23: The second key calculation node calculates the sixth point on the elliptic curve; S24: The second key calculation node calculates the second symmetric encryption key K j→i ; The calculation formula is: K j→i =KDF([T j→i ],id) Among them, [T j→i ] is the sixth point T on the elliptic curve j→i The vertical coordinate value of is a large integer; KDF is the key derivation function; id is the data identifier; S25: The second key calculation node decrypts the ciphertext data to obtain plaintext data; The method for the second key calculation node to calculate the fourth point on the elliptic curve includes the following sub-steps: S211: Map the data identifier to a point on the elliptic curve; The mapping formula is: P id =H C (id)·G Where G is the generator of the elliptic curve cyclic group of the selected prime order, P id H for G C (id) times point; It is a typical secure hash algorithm; S212: The second key calculation node generates a second random large integer; S213: The second key calculation node calculates the fourth point on the elliptic curve; The calculation formula is: F j→i =R j ·K j ·(K j +H ɑ (id))·P id Among them, F j→i is the fourth point on the elliptic curve; K j R is the root key of the second key calculation node when the system is initialized; j a second random large integer generated by the second key calculation node, and It is a typical secure hash algorithm; S214: The second key calculation node sends a message to the first key calculation node N i Send {F j→i ,id}; The method for the first key calculation node to calculate the fifth point on the elliptic curve comprises the following sub-steps: S221: The first key calculation node calculates the key according to {F j→i ,id}, calculate the fifth point on the elliptic curve; The calculation formula is: j→i =R j ·K j ·K i ·(K j +H ɑ (id))·(K i +H ɑ (id))·P id Among them, S j→i is the fifth point on the elliptic curve; K i The root key of the first key calculation node when the system is initialized; S222: The first key calculation node sends {S j→i ,id}; The second key calculation node N j Calculate the sixth point T on the elliptic curve j→i The method comprises the following sub-steps: S231: The second key calculation node calculates the multiplication inverse of the second random large integer on the positive integer prime number set; S232: Second key calculation node N j According to {S j→i ,id} calculate the sixth point on the elliptic curve; The calculation formula is: T j→i =K j ·K i ·(K j +H ɑ (id))·(K i +H ɑ (id))·P id +H b (pwd)·G Among them, T j→i is the sixth point on the elliptic curve; It is a typical secure hash algorithm; pwd is the decryption verification password.

3. A distributed cross-domain data encryption system, characterized in that It includes multiple service domains and multiple key computing nodes; wherein each key computing node corresponds to a service domain, and the encrypting party encrypts the data to be encrypted according to the distributed cross-domain data encryption method described in claim 1 through the key computing node of the service domain where the encrypting party is located; after the data encryption is completed, the encrypting party sends the encrypted data to the decrypting party, and after the decrypting party receives the encrypted data, according to the distributed cross-domain data decryption method described in claim 2, the decrypting party decrypts the data through the key computing node of the service domain where the decrypting party is located to obtain plaintext data.

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