The algorithm method you want use to encrypt the password.
The extension can encrypt with 3 different algorithm:
The MD4, MD5 and SHA-1 algorithms are secure hash functions. They take a string input, and produce a fixed size number - 128 bits for MD4 and MD5; 160 bits for SHA-1. This number is a hash of the input - a small change in the input results in a substantial change in the output. The functions are thought to be secure, in the sense that it would require an enormous amount of computing power to find a string which hashes to a chosen value. In others words, there's no way to decrypt a secure hash. The uses of secure hashes include digital signatures and challenge hash authentication. This document
is a good introduction to hashes.
MD4 is not considered as secure as the alternatives.
Some weaknesses have recently been discovered in the MD5 and SHA-1 algorithms (more information
). The hashes are designed so it is very difficult to find two messages that produce the same hash, this is called "collision resistance". Because MD5 is 128-bit, by random chance you will find a collision by producing 264 hashes. The weakness in MD5 is that a way has been found to produce such collisions with only 242 hashes. This makes producing collisions practical and I have seen an example of 100 different collisons.
The form text field the user will insert the password
The form field where insert the encrypted password, normally use an hidden field so the user don't see and cannot modify the encrypted value
Create the encrypt text with lowercase or uppercase letters
The character used to pad base-64 output to a multiple of 3 bytes
If checked create a base-64 pad character for Transitional RFC compliance
Bits input char:
Whether string input should be treated as ASCII or UniCode
define how many bits per input character.
ASCII: 8 bits (default)
Unicode: 16 bits
N.B. this is not the length of the encrypt password.