Wrapper around the system crypt(3) library for Erlang.
Which algorithms are supported by crypt are dependent on the system crypt(3) library. For example, Mac OS X only supports DES (booooooo!!!!).
crypt(Password, Salt) -> Crypted Types Password = string() Salt = string() Crypted = string() Calls the system crypt(3) function with the provided arguments. If crypt(3) is not supported by the OS, the crypt module will fail to load. Depending on your system crypt(3) library, errors may or may not be returned. Some implementations return NULL. If this occurs, crypt/2 will throw a bad arg exception. Other implementations may choose to return a fixed string (if this is a concern, the caller will need to test for this condition). The NetBSD man page for crypt(3) summarizes the situation as: The behavior of crypt() on errors isn't well standardized. Some implementations simply can't fail (unless the process dies, in which case they obviously can't return), others return NULL or a fixed string. Most implementations don't set errno, but some do. Version 2 of the Single UNIX Specification (``SUSv2'') specifies only returning NULL and setting errno as a valid behavior, and defines only one possible error (ENOSYS, ``The functionality is not supported on this implementation.'') Unfortunately, most existing applications aren't prepared to handle NULL returns from crypt(). The description below corresponds to this implementation of crypt() only. The behavior may change to match standards, other implementations or existing applications. crypt() may only fail (and return) when passed an invalid or unsupported setting, in which case it returns a pointer to a magic string that is shorter than 13 characters and is guaranteed to differ from setting. This behavior is safe for older applications which assume that crypt() can't fail, when both setting new passwords and authenticating against existing password hashes.
1> crypt:crypt("test","aa"). "aaqPiZY5xR5l." 2> crypt:crypt("test","$1$aaaaaaaa"). "$1$aaaaaaaa$lWxWtPmiNjS/cwJnGm6fe0" 3> crypt:crypt("test","$6$aaaaaaaa"). "$6$aaaaaaaa$HREHv6TuSmUS/7spCDO5Js3ssSZ6.iwVkUoVtatJUhJDKVmERrRKBTolrPMub2s5dX6IEjZg6d6wZzFRlidV41"
What is the maximum password and salt length?
There doesn't appear to be a limit. DES has an 8 character limit and MD5 has a 256 character limit, but for the other types, no idea.
sysconf(_SC_PASS_MAX) seems to return the limit on Solaris, but isn't available on Ubuntu.