The Python cryptography toolkit is intended to provide a reliable and stable base for writing Python programs that require cryptographic functions.
A central goal has been to provide a simple, consistent interface for similar classes of algorithms. For example, all block cipher objects have the same methods and return values, and support the same feedback modes.
Hash functions have a different interface, but it too is consistent over all the hash functions available. Some of these interfaces have been codified as Python Enhancement Proposal documents, as PEP 247, "API for Cryptographic Hash Functions", and PEP 272, "API for Block Encryption Algorithms".