  We propose a Fourier domain asymmetric cryptosystem for multimodal biometric
security. One modality of biometrics (such as face) is used as the plaintext,
which is encrypted by another modality of biometrics (such as fingerprint). A
private key is synthesized from the encrypted biometric signature by complex
spatial Fourier processing. The encrypted biometric signature is further
encrypted by other biometric modalities, and the corresponding private keys are
synthesized. The resulting biometric signature is privacy protected since the
encryption keys are provided by the human, and hence those are private keys.
Moreover, the decryption keys are synthesized using those private encryption
keys. The encrypted signatures are decrypted using the synthesized private keys
and inverse complex spatial Fourier processing. Computer simulations
demonstrate the feasibility of the technique proposed.
