This could be the place where one can "buy" or "find" a good cryptographic algorithm.
We deal exclusively with the flawed ones.
And those designed by people who did not know what they were doing,
and if the algorithm is still secure in practice, or secure enough, it was by accident.
Most of security claims in cryptography become obsolete within a decade.
However the cryptanalytic attacks are here to stay.
Code breaking is a noble sport in which major nations compete
with their brains, their hardware, and their software.
Algebraic attacks on block ciphers:
AES, Rijndael, Serpent, DES, KeeLoq, GOST, etc..
Algebraic attacks on stream ciphers: Toyocrypt, Lili-128, E0, Snow 2.0. etc..