The symmetric key cryptosystems have certain drawbacks which were highlighted in the previous chapter. To overcome the major disadvantage related to the compromise of one key being a potential threat to the whole system as it becomes a single point of failure, the Asymmetric key cryptographic techniques introduce two sets of keys: one that is publicly available and another that is a secret or private key that is retained with the communicating entities. It is considerable complex and expensive compared to symmetric key cryptography.