Multicast an efficient means of group communication plays a major role in wide variety of real time applications. Such communication requires authenticity of messages that is being transmitted in order to provide security services such as data integrity, non-repudiation, authenticity of data origin. Traditionally, messages sent using paper documents are authenticated by handwritten signatures. But, nowadays as messages are transmitted as electronic documents authentication could be achieved using public key cryptographic technique called Digital Signature. Digital Signature is a powerful tool which comprises of a string of zeros and ones is easy to validate and authenticate but difficult to forge. This paper surveys in depth various digital signature techniques, its advantages and disadvantages that are used for authenticating group communication. © 2016, Research India Publications.