Overview#All of our current Cryptography we typically discuss is around Computational Hardness Assumption.
In some cases, cryptographic protocols are found to have information theoretic security; the one-time pad is a common example. However, information theoretic security cannot always be achieved; in such cases, cryptographers fall back to Computational Hardness Assumption.
Roughly speaking, this means that these systems are secure assuming that any adversaries are computationally limited, as all adversaries are in practice. Because hardness of a problem is difficult to prove, in practice certain problems are "assumed" to be difficult.
More Information#There might be more information for this subject on one of the following:
- Cryptographically Weak
- Cryptographically secure pseudorandom number generator
- Pseudorandom generators