Hash function for security

i want to know about hash function how they using for security purpose ,actually i am new learner for php i want to know which function that i can used .please tell me how can i do this .thank you .

Hash functions are pseudo random number generators (PRNG). From this generalization its generally accepted that the performance of hash functions and also comparisons between hash functions can be achieved by treating hash function as PRNGs.

Various Forms Of Hashing

String Hashing
Cryptographic Hashing
Geometric Hashing
Bloom Filters

this topic is really big and interesting and more important in cryptography i think you will learn it in your course further

Hash algorithms: GOST | HAS-160 | HAVAL | LM hash | MDC-2 | MD2 | MD4 | MD5 | N-Hash | RadioGatún | RIPEMD | SHA family | Snefru | Tiger | WHIRLPOOL | crypt(3) DES

you can use hash function in php md5 you can use here is some fun try this link look how md5 sequence get calculated http://www.miraclesalad.com/webtools/md5.php

for more implementation you need to learn and practice .

this implementation is more usefule in all aspect check this link for more detaie idea about internet encryption http://www.faqs.org/rfcs/rfc4894.html