Single Sign On (SSO) is an authentication mechanism that enables legal user with a single credential to be
authenticated by multiple service providers in a distributed computer networks. SSO obtains credential from trusted
authorities i.e., Smart Card Producing Center (SCPC) and Trusted Credential Privacy (TCP) which is used for mutual
authentication and authorization of legal users. Chang-Lee coined a new SSO scheme which makes use of SCPC for
mutual authentication and session key establishment whereas Schnorr signature makes use of TCP which generates and
verifies the signature for user’s authentication. RSA algorithm and Attribute Based Encryption (ABE) is used for
encryption and decryption of messages in which ABE tends to be more efficient than RSA based algorithm. ABE is a
new public key based on one-to-many encryption that allows users to decrypt the message based on set of attributes and
access policies. Decryption is an expensive process and this ABE system eliminates the decryption overhead using
outsourced decryption. Integrity of data is maintained by verification of the cipher text which guarantees that the
encrypted and decrypted files are same and original message is recovered using hash technique in case of any
modifications in the file