Small public-key based digital signatures for authentication

Apparatus for use in authentication between two entities having agreed on the use of a common modulus N, the apparatus comprising:

• means for receiving a first authentication signature value;
• means for generating a pseudorandom string value from an input value;
• means for generating a first public key value based on the modulus N and the pseudorandom string value;
• means for generating a private key value corresponding to the first public key value;
• means for generating a shared secret value based on the modulus N, the private key value and the first public key value;
• means for calculating a second authentication signature value using the shared secret value;
• and
• means for comparing the first authentication signature value with the second authentication signature value.

Apparatus for use in authentication between two entities having agreed on the use of a common modulus N, the apparatus comprising:

• a storage medium storing instructions;
• and
• a processor communicatively coupled to the storage medium and configured to execute the instructions to implement:
• a receiver unit configured to receive a first authentication signature value;
• a pseudo-random generator configured to generate a pseudorandom string value from an input value;
• a key generating unit configured to generate a first public key value based on the modulus N and the pseudorandom string value, and a private key value corresponding to the first public key value;
• a shared secret value generating unit configured to generate a shared secret value based on the modulus N, the private key value and the first public key value;
• a message authentication code unit configured to calculate a second authentication signature value using the shared secret value;
• and
• a comparing unit configured to compare the first authentication signature value with the second authentication signature value.