The Validation Information

1. The Validation Information • The idea is to use the stable biometric as an encryption key to an RSA cryptosystem to encode the message digest of the document to be sent. • The decryption key would be made public so that anybody is able to get message digest and the receiver can match it with that of the document in the fuzzy vault to establish its validity.

2. Issue related to Validation Information • Any key of an RSA cryptosystem generated out of primes p and q should be coprime to the euler’s function of pq i.e. (p-1)(q-1) • So, the stable biometric can’t be directly used as a key. • Proposed solution: map the set of stable biometrics to the set of possible keys. • The numeric representation of the stable biometric feature (say α) is mapped to

3. Overall System Working • Document Sending • The sender creates the previously mentioned Modified Fuzzy Vault using cancelable biometric to lock the document. • Stable features are extracted from a secret biometric template and an RSA cryptosystem is generated using it as described before. • The decryption key is made public and encryption key is used to encrypt the message digest of document. • The Fuzzy Vault and the Validation Information is sent along with other necessary identification information to the receiver.

4. Document Receiving • The receiver opens the Fuzzy Vault using the key corresponding to the desired security level to get the document. • Receiver extracts the message digest from the Validation Information using the publicly available decryption key. • He extracts the message digest from the document and matches it with that in the Validation Information to verify the document. • The Validation Information part has been implemented in matlab and has been tested on data from a single fingerprint to give accurate results with certain values of constants used.