Ns sha1

Function

ns_sha1 string

Description

Returns a 40-character, hex-encoded string containing the SHA1 hash of the first argument.

Usage

Example 1:

set sRawPassword "mypassword"
set sPassword [ns_sha1 $sRawPassword]
ns_adp_puts $sPassword
# 04003622EB9D0F788CE7568C7EED23809534365A

Usually this function is used with either a prefixed or postfixed salt, as without a salt it is succeptible to dictionary-based attacks.

Example 2:

set sSalt "salty"
set sRawPassword "mypassword"
set sPassword [ns_sha1 ${sRawPassword}${sSalt}]
# B48FB74597C11FC609DBE912992085EB07847FB6

Good salts are at least of moderate length and consist of random characters. Take note, however, that you would need to be able to retrieve the same salt to perform a match against the previous hash given the same unsalted input. Hash functions for human-chosen alphanumeric passwords are usually succeptible to dictionary-based attacks.

This function is provided by the nssha1 module, provided as a Debian package among others.

Caveat

Unfortunately, this implementation does not seem to be immediately compatible with other SHA1 implementations.

Postgresql:

template1=> select encode(digest('mypassword','SHA1'),'hex');
                  encode
------------------------------------------
 91dfd9ddb4198affc5c194cd8ce6d338fde470e2
(1 row)

Interestingly, the Tcllib implementation of SHA1 "works", see:

nscp 1> package require sha1
2.0.1

nscp 2> sha1::sha1 -hex "mypassword"
91dfd9ddb4198affc5c194cd8ce6d338fde470e2

SEE ALSO

ns_uuencode, ns_uudecode, ns_crypt, ns_rand