Digital Signature protects the document`s integrity and binds the authenticity of the user who have signed. Present Digital Signature algorithm confirms authenticity but it does not ensure secrecy of the data. Techniques like encryption and decryption are needed to be used for this purpose. Biometric security has been a useful way for authentication and security as it provides a unique identity of the user. In this paper we have discussed the user authentication process and development of digital signatures. Authentication was based on hash functions which uses biometric features. Hash codes are being used to maintain the integrity of the document which is digitally signed. For security purpose, Encryption and Decryption techniques are used to develop a bio -cryptosystem. User information when gets concatenated with feature vector of biometric data, which actually justifies the sense of authentication. Various online or offline transaction where authenticity and integrity is the top most priority can make use of this development.