Security Services of Secret Key Encryption
Secret key encryption can be used to achieve data confidentiality, data integrity, and origin authenticity.
Using a secret key algorithm to encipher a data content allows entities with the right secret key only to decrypt and retrieve the original form of the disguised data. Reliability of the confidentiality service afforded by secret key cryptography depends upon the strength of the encryption algorithm, and, more importantly, is dependent upon the length of the key used. Recall that the key length directly affects the size of the corresponding key space. A longer lifetime of a secret key also may contribute to diminishing the assurance in its use for a confidentiality service. The longer a key is used the more likely an exhaustive key search attack will succeed. Most modern security protocols make use of secret keys that remain valid for the lifetime of a particular communications session only.
A confidentiality service enabled through a computationally secure cryptographic algorithm allows users to transmit private information over open networks. Similarly such information can be stored in accessible media without concerned for compromise. Computationally the cost of data confidentiality depends upon the encryption algorithm used and is evidently proportionate to the size of data to be enciphered.