Digital signature is a technique that is utilized to check the authenticity of a message transmitted electronically. The digital signature technique is based on a public key method. The meant transmitter signs his / her message of his / her private key and the meant receiver checks that with the public key of the transmitter. Digital signatures also ensure authentication of messages, integrity verification, and nonrepudiation systems. This paper presents the concept of Biometric Signature: a recent technique to digitally sign a message utilizing biometrics- associated with digital signature key creation, so, merging the benefits of Public Key Infrastructure (PKI), through the utilize of biometric-based digital signature creation that is secure, reliable, quickly-comfortable, non-invasive, and clearly describes the transaction creator. It also proposes biometric signature algorithms utilizing the commonly utilized RSA digital signature technique and shows the problems related to them. This paper analyses the security of the modulus and the size of the keys used and computes the strength of RSA based on the number of bits in the key (iris template). The time of the scheme is calculated and it is extremely small (in sec).