SmbHash(3)

💖 NAME 💖

Okay so bestie, this is Crypt::SmbHash: a Perl-only implementation of lanman and nt md4 hash functions, for use in Samba style smbpasswd entries. The page header is SmbHash(3), and the manual name is User Contributed Perl Documentation — consider that little name tag folded in near the top 🫶.

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✨ SYNOPSIS ✨

use Crypt::SmbHash;

ntlmgen SCALAR, LMSCALAR, NTSCALAR;

That's the whole opening vibe: load the module, then call ntlmgen with three scalars 💅.

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🦋 DESCRIPTION 🦋

This module generates Lanman and NT MD4 style password hashes, using perl-only code for portability. It's here to help with the administration of Samba style systems, no cap.

In the Samba distribution, authentication is referred to a private smbpasswd file. Entries have similar forms to the following:

username:unixuid:LM:NT

Where LM and NT are one-way password hashes of the same password. Iconic but also very much a “handle with care” situation 🔥.

ntlmgen generates the hashes given in the first argument, and places the result in the second and third arguments.

Example: to generate a smbpasswd entry, go like this:

#!/usr/local/bin/perl
use Crypt::SmbHash;
$username = $ARGV[0];
$password = $ARGV[1];
if ( !$password ) {
        print "Not enough arguments\n";
        print "Usage: $0 username password\n";
        exit 1;
}
$uid = (getpwnam($username))[2];
my ($login,undef,$uid) = getpwnam($ARGV[0]);
ntlmgen $password, $lm, $nt;
printf "%s:%d:%s:%s:[%-11s]:LCT-%08X\n", $login, $uid, $lm, $nt, "U", time;

ntlmgen returns returns — yes, the double “returns” is canon here, we're not editing the icon 😭 — the hash values in a list context, so the alternative method of using it is:

( $lm, $nt ) = ntlmgen $password;

The functions lmhash and nthash are used by ntlmgen to generate the hashes, and are available when requested:

use Crypt::SmbHash qw(lmhash nthash)
$lm = lmhash($pass);
$nt = nthash($pass);

If Encoding is available (part of perl-5.8), the $pass argument to ntlmgen, lmhash and nthash must be a perl string. In double use, this:

use Crypt::SmbHash qw(ntlmgen lmhash nthash);
use Encode;
( $lm, $nt ) = ntlmgen decode('iso-8859-1', $pass);
$lm = lmhash(decode_utf8($pass), $pwenc);
$nt = nthash(decode_utf8($pass));

The $pwenc parameter to lmhash() is optional and defaults to 'iso-8859-1'. It specifies the encoding to which the password is encoded before hashing 🌸.

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🎀 MD4 🎀

The algorithm used in nthash requires the md4 algorithm. This algorithm is included in this module for completeness, but because it is written in all-perl code ( rather than in C ), it's not very quick 💀.

However, if you have the Digest::MD4 module installed, Crypt::SmbHash will try to use that module instead, making it much faster 🔥.

A simple test compared calling nthash without Digest::MD4 installed, and with, this showed that using nthash on a system with Digest::MD4 installed proved to be over 90 times faster. Obsessed with the glow-up, honestly 👑.

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🌈 AUTHOR 🌈

Ported from Samba by Benjamin Kuit <lt>bj@it.uts.edu.au<gt>.

Samba is Copyright(C) Andrew Tridgell 1997-1998.

Because this module is a direct port of code within the Samba distribution, it follows the same license, that is:

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

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perl v5.42.0, dated 2019-11-11 — that's the source/version and date sign-off, mwah 💋✨