crypt

• char *crypt(const char *key, const char *salt);
• The key is the plain text string to be encrypted
• The salt is a randomization factor.
  • A value in [a-zA-Z./]
  • It was an attempt to make it more difficult to store all encrypted passwords.
  • It increased the storage space required by a factor of 4096
• With DES, crypt only used the first 8 characters of the plain text password.
• This has never been a good solution, see this paper about faster crypt from 1988.
• Here is a really nice paper on the subject of rainbow tables.
• Modern Salts
  • Currently glib c supports the following salts
    • 1: MD5
    • 5: SHA-256
    • 6: SHA-5122
  • SHA is the Secure Hash Algorithm.
  • To use these, use a salt in the form of
  • $id$salt$encrypted
    • ID is from the table.
    • Salt is up to 16 characters from [a-zA-Z0-9./]
  • The entire plain text password is used.