Method and apparatus for entity authentication and key distribution secure against off-line adversarial attacks

A method of authenticating a communication partner in an insecure communication channel in a distributed data processing system wherein authenticity of communication partners is determined by possession of a long-lived shared secret key, comprising the method steps of:

• (a) exchanging data flows between communication partners to define a composite key, in said distributed data processing system wherein at least a portion of said data flows has been encrypted or otherwise masked in a manner which utilizes said long-lived shared secret key;
• (b) passing at least one authentication tag between said communication partners, wherein said at least one authorization tag is defined by a transform taken over a plurality of parameters and at least partially based on said composite key, said transform including at least one of (i) a message authentication code which is keyed by said long-lived shared secret key;
• (ii) a cryptographic hash function taken over said long-lived shared secret key;
• and (iii) a masking operation involving said long-lived shared secret key;
• and
• (c) utilizing said authentication tag to determine authenticity of at least one communication partner.

A method of authenticating a communication partner over an insecure communication channel wherein authenticity of communication partners is determined by possession of a long-lived shared secret key, comprising the method steps of:

• (a) short-lived distributing to said communication partners a composite key in data flows between communication partners;
• (b) passing at least one authentication tag between said communication partners, wherein said at least one authorization tag is defined by a transform taken over a plurality of parameters and at least partially based on said composite key, said transform including at least one of (i) a message authentication code which is keyed by said long-lived shared secret key (ii) a cryptographic hash function taken over said long-lived shared secret key;
• and (iii) a masking operation involving said long-lived shared secret key;
• and
• (c) utilizing said authentication tag to determine authenticity of at least one communication partner.

Means for authenticating a communication partner in an insecure communication channel wherein authenticity of communication partners is determined by possession of a long-lived shared secret key, comprising:

• (a) means for exchanging data flows between communication partners, to define a composite key, wherein at least a portion of said data flows has been encrypted or otherwise masked in a manner which utilizes said long-lived shared secret key;
• (b) means for passing at least one authentication tag between said communication partners, wherein said at least one authorization tag is defined by a transform taken over a plurality of parameters and at least partially based on said composite key, said transform including at least one of (i) a message authentication code which is keyed by said long-lived shared secret key;
• (ii) a cryptographic hash function taken over said long-lived shared secret key;
• and (iii) a masking operation involving said long-lived shared secret key;
• and
• (c) means for utilizing said authentication tag to determine authenticity of at least one communication partner.