With the growth in the demand for data exchange between any electronic system, the need for security of the information exchanged has become a necessity. The protection of the information related to the user from getting exposed to unauthorized person becomes a challenging issue. Hence, there is a requirement to encrypt the private user data to maintain the privacy. The paper focuses on maintaining the privacy of the sender information which is used for authentication of the image transmitted in the communication system. By embedding the information of the sender in the encrypted form, privacy for the sender information is obtained. The encryption of the sender data can be performed by using various encryption algorithms. In this work, encryption of the information of the person sending the image which is taken in the form of text file of varying size is performed using blowfish encryption algorithm which is a symmetric key block cipher. The length of the key used in blowfish for encryption and decryption ranges from 32 to 448 bits and the block size used is 64 bits. The structure of the algorithm is fiestal network. The work is implemented using MATLAB.