PHPの crypt()を自力で実装する例

php - How to create md5 hash as the crypt function generates with a md5 salt using the md5 function, not the crypt function? - Stack Overflow

Here's code in Java that implements the same function. This may help you to do the same in other languages.

For PHP, you may want to look into this code:

思ったよりややこしいのね。base64_encode()とかmd5()は使えないのかしらん。