Abstract: The described system and method provide for an encryption and authentication technique that achieves enhanced integrity verification through assured error-propagation using a multistage sequence of pseudorandom permutations. The method generates intermediate data-dependent cryptographic variables at each stage, which are systematically combined into feedback loops. The encryption technique also generates an authentication tag with minimal post processing that is the size of the state. The size of the state is dependent on the number of pseudorandom permutations and the size of the LFSR. The authentication tag provides a unique mapping to the plaintext for any number of plaintext blocks that is less than or equal the size of the state. In addition to being a stand alone encryption algorithm, the disclosed technique is applicable to any mode that uses pseudorandom permutations such as, key dependent lookup tables, S-Boxes, and block ciphers such as RC5, TEA, and AES.

Abstract: The described system and method provide for an encryption and authentication technique that achieves enhanced integrity verification through assured error-propagation using a multistage sequence of pseudorandom permutations. The method generates intermediate data-dependent cryptographic variables at each stage, which are systematically combined into feedback loops. The encryption technique also generates an authentication tag with minimal post processing that is the size of the state. The size of the state is dependent on the number of pseudorandom permutations and the size of the LFSR. The authentication tag provides a unique mapping to the plaintext for any number of plaintext blocks that is less than or equal the size of the state. In addition to being a stand alone encryption algorithm, the disclosed technique is applicable to any mode that uses pseudorandom permutations such as, key dependent lookup tables, S-Boxes, and block ciphers such as RC5, TEA, and AES.

Abstract: The present invention describes a system and method for securely identifying and authenticating devices in a symmetric encryption system. An RFID tag can generate indicators using encryption state variables and a symmetric key. An RFID reader, after receiving the encryption state variables from the tag, may identify the tag by performing an exhaustive key search in a key database. Each key in the database may be tested by using the key and encryption state variables to perform an encryption operation similar to that performed by the tag. The result is then compared with the received tag indicators to determine if the tag has been identified. A rotor-based encryption scheme provides for a low cost key search while providing resilience against cloning, tracking, tampering and replay attacks.