[NTH] New Chainhash functions (new contributers welcome)

• Difficulty (1-10): 3
• Location/Files: pwfunc.h/pwfunc.cpp
• Current behaviour: A chainhash is an hash which is applied on its previous result (for a given number of iterations). You can copy some code from the implemented chainhashes. use this->hash->hash() as the hash function. there are already 4 types of chainhashes imnplemented.:
  1. A chainhash which hashes the last hash again
  2. A chainhash which hashes the last hash + a constant salt
  3. A chainhash which hashes the last hash + an incrementing number
  4. A chainhash which hashes the last hash + a constant salt + an incrementing number
  5. A chainhash which hashes the last hash + a quadratic salt #4
• Wished behaviour: New chainhashes wished Define you own chainhash function in the pwfunc files. Constraints:
  1. it has to take at least a std::string password and an iteration number
  2. it can take more arguments if needed, but all added arguments have to be under 256 Bytes memory (because we have to save them in a buffer, this constraint is more theoretically but you should not expect long strings or other big data to get passed)
  3. the result has to be the same with the same arguments (obviously)

if you need help or have a hard time understanding certain things, you are welcome to comment on this issue

Good luck