2356results about "Cryptographic attack countermeasures" patented technology

This invention relates to cryptographic communications methods and systems that protect a server from a connection depletion attack. Specifically, the invention presents a method for allocating a resource comprising the steps of receiving a resource allocation request from a client, imposing a computational task and a time limit for correct completion of the task upon the client, verifying that the task was performed correctly within the time limit, and allocating the resource if the task was correctly performed within the time limit.

An integrated circuit device comprising: a circuit which uses encryption; and an encapsulation packaging layer; in which the circuit is responsive to at least one physical parameter of the encapsulation to apply the encryption and/or decryption by reading the key therefrom, so that tampering with the encapsulation to gain access to the circuit causes the encryption and/or decryption to fail.

In a system for disconnected authentication, verification records corresponding to given authentication token outputs over a predetermined period of time, sequence of events, and/or set of challenges are downloaded to a verifier. The records include encrypted or hashed information for the given authentication token outputs. In one embodiment using time intervals, for each time interval, token output data, a salt value, and a pepper value, are hashed and compared with the verification record for the time interval. After a successful comparison, a user can access the computer. A PIN value can also be provided as an input the hash function. A portion of the hash function output can be used as a key to decrypt an encrypted (Windows) password, or other sensitive information.

A method for protecting data against power analysis attacks includes at least a first phase of executing a cryptographic operation for ciphering data in corresponding enciphered data through a secret key. The method includes at least a second phase of executing an additional cryptographic operation for ciphering additional data in corresponding enciphered additional data. An execution of the first and second phases is undistinguishable by the data power analysis attacks. Secret parameters are randomly generated and processed by the at least one second phase. The secret parameters include an additional secret key ERK for ciphering the additional data in the corresponding enciphered additional data.

A database encryption system and method, the Structure Preserving Database Encryption (SPDE), is presented. In the SPDE method, each database cell is encrypted with its unique position. The SPDE method permits to convert a conventional database index into a secure one, so that the time complexity of all queries is maintained. No one with access to the encrypted database can learn anything about its content without the encryption key. Also a secure index for an encrypted database is provided. Furthermore, secure database indexing system and method are described, providing protection against information leakage and unauthorized modifications by using encryption, dummy values and pooling, and supporting discretionary access control in a multi-user environment.

A method and system establishing cryptographic communications between a remote device and a medical device, with the medical device having less processing power than the remote device are disclosed. The method may comprise establishing unencrypted communication between the remote device and the medical device, generating an asymmetric key pair by the remote device comprising a public key and a private key, generating a key request message and sending of the key request message together with the public key to the medical device, generating a pre-master key and encryption of the pre-master key with the received public key by the medical device, generating a key response message and sending of the key response message together with the encrypted pre-master key from the medical device to the remote device, decrypting the encrypted pre-master key with the private key by the remote device, and deriving a master key as a symmetric key from the pre-master key.

A method and apparatus for fine-grained, trust-based rate limiting of network requests distinguishes trusted network traffic from untrusted network traffic at the granularity of an individual user/machine combination, so that network traffic policing measures are readily implemented against untrusted and potentially hostile traffic without compromising service to trusted users. A server establishes a user/client pair as trusted by issuing a trust token to the client when successfully authenticating to the server for the first time. Subsequently, the client provides the trust token at login. At the server, rate policies apportion bandwidth according to type of traffic: network requests that include a valid trust token are granted highest priority. Rate policies further specify bandwidth restrictions imposed for untrusted network traffic. This scheme enables the server to throttle untrusted password-guessing requests from crackers without penalizing most friendly logins and only slightly penalizing the relatively few untrusted friendly logins.

A method and a circuit system for checking an m out of n code are provided. The method uses a code checker, to which at least one code reducer is assigned, a reduction of the code word width to in each case half being carried out using the at least one code reducer until a 1 out of x (x=n/2, n/4, n/8 . . . ) code or another code which is not reducible further in this way is provided, each step of the code reducer additionally being connected to different bits of a counter, the 1 out of x code or the code which is not further reducible being checked and additionally the signal pairs of each step being checked.

A method, system and computer program is provided for protecting against one or more security attacks from third parties directed at obtaining user credentials on an unauthorized basis, as between a client computer associated with a user and a server computer is provided. The server computer defines a trusted Public Key Cryptography utility for use on the client computer. The Public Key Cryptography utility is operable to perform one or more cryptographic operations consisting of encrypting/decrypting data, authenticating data, and/or authenticating a sender, decrypting and/or verifying data. The user authenticates to the Public Key Cryptography utility, thereby invoking the accessing of user credentials associated with the user, as defined by the server computer. The Public Key Cryptography Utility facilitates the communication of the user credentials to the server computer, whether directly or indirectly via an authentication agent, the server computer thereby authenticating the user. In response, the server computer providing access to one or more system resources linked to the server computer to the user. The present invention also provides a series of methods enabling the server computer to authenticate the user by operation of the Public Key Cryptography utility and/or based on enrolment of the user and providing the Public Key Cryptography utility to the user.

A method for secure bidirectional communication between two systems is described. A first key pair and a second key pair are generated, the latter including a second public key that is generated based upon a shared secret. First and second public keys are sent to a second system, and third and fourth public keys are received from the second system. The fourth public key is generated based upon the shared secret. A master key for encrypting messages is calculated based upon a first private key, a second private key, the third public key and the fourth public key. For re-keying, a new second key pair having a new second public key and a new second private key is generated, and a new fourth public key is received. A new master key is calculated using elliptic curve calculations using the new second private key and the new fourth public key.

A communication system and a security assurance device are proposed, which are capable of assuring that a target party for communication is implementing security countermeasures. A server 3 transmits information 104 necessary for AC issuance to a security assurance authority 2. The security assurance authority 2 verifies the security of the server 3 during communication based upon this information necessary for AC issuance 104. And, when the security of the server 3 during communication is confirmed, the security assurance authority 2 issues an AC 105 which proves the security of the server 3 during communication, and transmits it to the server 3. Upon receipt of this AC 105, the server 3 transmits the AC 105 to a client 4, according to a connection request from the client 4. And, upon receipt of this AC 105, the client 4 verifies the security during communication of the server 3, based upon the AC 105.

The invention relates to a system and method of hiding cryptographic private keys. While public/private key encryption systems are considered to be secure, the private keys ultimately must be stored in some location—in fact, in some digital commerce systems the private key is sent to the end user as part of an executable file such as an audio player and audio file. Thus, attackers can obtain access to the private key. The broad concept of the invention is to split the private key up into parts which are obfuscated, but still kept in a form that allows the encrypted data to be decrypted. One technique for obfuscating the private key uses modulo arithmetic.

To provide a secure cryptographic device such as an IC card which can endure TA (Timing Attack), DPA (Differential Power Analysis), SPA (Simple Power Analysis), or the like as an attaching method of presuming secret information held therein, when the secret information held in the card or another information which is used in the secret information or an arithmetic operation using such secret information when such an arithmetic operation is performed is shown by a plurality of expressing methods and the arithmetic operation is performed, thereby making an arithmetic operation processing method different each time the arithmetic operation is performed and making each of an arithmetic operation time, an intensity of a generated electromagnetic wave, and a current consumption different.

A method of evaluating secrets in a computer system's trusted execution environment, wherein after evaluation of secrets, a securely stored encryption key is either retrieved or deleted upon entering corresponding secret (password, graphical password, biometric information, data sequence, security token, etc.) or secrets. Deletion of the encryption key can happen in a verifiable manner or in a non-verifiable manner. If a storage is encrypted with the encryption key, deletion of the encryption key makes the encrypted storage irreversibly undecryptable, while retrieval of the key permits decryption of the storage. Two encryption keys can be used to encrypt two separate storages, and then securely stored and processed in the trusted execution environment. Each of the two encryption keys can be retrieved using one or more associated secrets (passwords, etc.), and one or more other secrets would delete the encryption key associated with a preselected storage. During sleep-wake event a computer system's memory can be encrypted with a symmetric key, and the symmetric key can be secured by encrypting with a public encryption key. Corresponding private key is retrieved to decrypt the symmetric key upon evaluation of associated password (secret) in trusted execution environment, while the private key is deleted upon evaluation of one or many preselected deletion password (secret) leaving the encrypted memory undecryptable.

Reader (420) for determining the validity of a connection to a transponder (440), designed to measure a response time of a transponder (440) and to authenticate the transponder (440) in two separate steps. Transponder (440) for determining the validity of a connection to a reader (420), wherein the transponder (440) is designed to provide information for response time measurement to said reader (420) and to provide information for authentication to said reader (420) in two separate steps, wherein at least a part of data used for the authentication is included in a communication message transmitted between the reader (420) and the transponder (440) during the measuring of the response time.

Systems for generating an identifying response pattern comprising a memory (120) used as a physically unclonable function configured for generating a response pattern dependent on physical, at least partially random characteristics of said memory may be vulnerable to freezing attacks and to aging. A memory-overwriting device (110) configured for overwriting at least a first portion of the plurality of memory locations to obscure the response pattern in the memory avoids freezing attacks. An anti-degradation device (160) configured to write to each respective location of a second portion of the plurality of memory locations an inverse of a response previously read from the memory reduces the effects of aging.

The present invention makes it difficult for unauthorized parties to estimate processing and a secret key based upon the waveforms of power consumption of an IC card chip by changing a processing order in the IC card chip so that it is not estimated by the attackers. In an information processing apparatus comprising storing means having a program storing part for storing programs and a data storing part for storing data, an operation processing unit, means for inputting data to be operated on in the operation processing unit, and means for outputting operation processing results on the data by the operation processing unit, an arithmetic operation method is provided which comprises the steps of: for two integers K1 and K2, when finding a value F(K, A) of a function F satisfying F(K1+K2, A)=F(K1, A)◯F(K2, A) (◯ denotes an arithmetic operation in a communtative semigroup S. K designates an integer and A designates an element of S), decomposing the K to the sum of m integers K[0]+K[1]+ . . . K[m−1]; using T(0), T(1), . . . T(m−1) resulting from rearranging a string of the m integers 0, 1, . . . m−1 by permutation T (the result corresponds one for one to the integer string 0, 1, . . . m−1); and operating on terms F(K[T(0)], A) to F(K[T(m−1)], A) on the right side of

F(K, A)=F(K[T(0)], A)◯F(K[T(1)], A)◯ . . . F(K[T(m−1)], A) . . .   (expression 1)

in the order of F(K[T(0)], A), F(K[T(1)], A), . . . F(K[T(m−1)], A) to find F(K, A).

A method of computing a cryptographic key to be shared between a pair of correspondents communicating with one another through a cryptographic system is provided, where one of the correspondents receives a certificate of the other correspondents public key information to be combined with private key information of the one correspondent to generate the key. The method comprises the steps of computing the key by combining the public key information and the private key information and including in the computation a component corresponding to verification of the certificate, such that failure of the certificate to verify results in a key at the one corespondent that is different to the key computed at the other correspondent.

A cryptographic method and related implements the Rijndael—AES encryption standard. In one improvement, the decryption round keys are generated on a round by round basis from the final Nk round keys saved from a previous encryption key scheduling operation. Latency and memory requirements are thereby minimized. S-boxes for the AES key generation and cipher operation itself, may be implemented multiple times in different ways with different power signatures, with a pseudo-random selection of the pathway for the different bytes to be substituted. The premix operation occurs simultaneously with the generation of first round keys, and a dummy circuit with substantially identical timing as the real premix circuitry adds power consumption noise to the premix.

A method and an apparatus capable of realizing at a high speed an elliptic curve cryptography in a finite field of characteristic 2, in which the elliptic curve is given by y²+xy=x³+ax²+b (b≠0) and an elliptic curve cryptography method which can protect private key information against leaking from deviation information of processing time to thereby defend a cipher text against a timing attack and a differential power analysis attack are provided. To this end, an arithmetic process for executing scalar multiplication arithmetic d(x, y) a constant number of times per bit of the private key d is adopted. Further, for the scalar multiplication d(x, y), a random number k is generated upon transformation of the affine coordinates (x, y) to the projective coordinates for thereby effectuating the transformation (x, y)→[kx, ky, k] or alternatively (x, y)→[k²x, k³y, k]. Thus, object for the arithmetic is varied by the random number (k).