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;;; md4.el --- MD4 Message Digest Algorithm. -*- lexical-binding: t -*-
;; Copyright (C) 2001, 2004, 2007-2025 Free Software Foundation, Inc.
;; Author: Taro Kawagishi <tarok@transpulse.org>
;; Keywords: MD4
;; Old-Version: 1.00
;; Created: February 2001
;; This file is part of GNU Emacs.
;; GNU Emacs 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 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs 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.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; The MD4 Message-Digest Algorithm.
;;
;; The security of the MD4 hashing algorithm is very poor to
;; non-existent. It was declared obsolete by RFC 6150 in 2011:
;; https://tools.ietf.org/html/rfc6150
;;
;; You probably want to use `secure-hash' instead.
;;; Code:
;;;
;;; MD4 hash calculation
(defvar md4-buffer (make-vector 4 '(0 . 0))
"Work buffer of four 32-bit integers.")
(defun md4 (in n)
"Return the MD4 hash for a string IN of length N bytes.
The returned hash is 16 bytes long. N is required to handle
strings containing the character 0.
The security of the MD4 hashing algorithm is very poor to
non-existent. It was declared obsolete by RFC 6150 in 2011.
You probably want to use `secure-hash' instead."
(let (m
(b (cons 0 (* n 8)))
(i 0)
(buf (make-string 128 0)) c4)
;; initial values
(aset md4-buffer 0 '(26437 . 8961)) ;0x67452301
(aset md4-buffer 1 '(61389 . 43913)) ;0xefcdab89
(aset md4-buffer 2 '(39098 . 56574)) ;0x98badcfe
(aset md4-buffer 3 '(4146 . 21622)) ;0x10325476
;; process the string in 64 bits chunks
(while (> n 64)
(setq m (md4-copy64 (substring in 0 64)))
(md4-64 m)
(setq in (substring in 64))
(setq n (- n 64)))
;; process the rest of the string (length is now n <= 64)
(setq i 0)
(while (< i n)
(aset buf i (aref in i))
(setq i (1+ i)))
(aset buf n 128) ;0x80
(if (<= n 55)
(progn
(setq c4 (md4-pack-int32 b))
(aset buf 56 (aref c4 0))
(aset buf 57 (aref c4 1))
(aset buf 58 (aref c4 2))
(aset buf 59 (aref c4 3))
(setq m (md4-copy64 buf))
(md4-64 m))
;; else
(setq c4 (md4-pack-int32 b))
(aset buf 120 (aref c4 0))
(aset buf 121 (aref c4 1))
(aset buf 122 (aref c4 2))
(aset buf 123 (aref c4 3))
(setq m (md4-copy64 buf))
(md4-64 m)
(setq m (md4-copy64 (substring buf 64)))
(md4-64 m)))
(concat (md4-pack-int32 (aref md4-buffer 0))
(md4-pack-int32 (aref md4-buffer 1))
(md4-pack-int32 (aref md4-buffer 2))
(md4-pack-int32 (aref md4-buffer 3))))
(defsubst md4-F (x y z) (logior (logand x y) (logand (lognot x) z)))
(defsubst md4-G (x y z) (logior (logand x y) (logand x z) (logand y z)))
(defsubst md4-H (x y z) (logxor x y z))
(defmacro md4-make-step (name func)
`(defun ,name (a b c d xk s ac)
(let*
((h1 (+ (car a) (,func (car b) (car c) (car d)) (car xk) (car ac)))
(l1 (+ (cdr a) (,func (cdr b) (cdr c) (cdr d)) (cdr xk) (cdr ac)))
(h2 (logand 65535 (+ h1 (ash l1 -16))))
(l2 (logand 65535 l1))
;; cyclic shift of 32 bits integer
(h3 (logand 65535 (if (> s 15)
(+ (ash h2 (- s 32)) (ash l2 (- s 16)))
(+ (ash h2 s) (ash l2 (- s 16))))))
(l3 (logand 65535 (if (> s 15)
(+ (ash l2 (- s 32)) (ash h2 (- s 16)))
(+ (ash l2 s) (ash h2 (- s 16)))))))
(cons h3 l3))))
(md4-make-step md4-round1 md4-F)
(md4-make-step md4-round2 md4-G)
(md4-make-step md4-round3 md4-H)
(defsubst md4-add (x y)
"Return 32-bit sum of 32-bit integers X and Y."
(let ((h (+ (car x) (car y)))
(l (+ (cdr x) (cdr y))))
(cons (logand 65535 (+ h (ash l -16))) (logand 65535 l))))
(defsubst md4-and (x y)
(cons (logand (car x) (car y)) (logand (cdr x) (cdr y))))
(defun md4-64 (m)
"Calculate MD4 hash of M.
M is a 64-bytes chunk, represented as 16 pairs of 32-bit integers.
The resulting MD4 value is placed in `md4-buffer'."
(let ((a (aref md4-buffer 0))
(b (aref md4-buffer 1))
(c (aref md4-buffer 2))
(d (aref md4-buffer 3)))
(setq a (md4-round1 a b c d (aref m 0) 3 '(0 . 0))
d (md4-round1 d a b c (aref m 1) 7 '(0 . 0))
c (md4-round1 c d a b (aref m 2) 11 '(0 . 0))
b (md4-round1 b c d a (aref m 3) 19 '(0 . 0))
a (md4-round1 a b c d (aref m 4) 3 '(0 . 0))
d (md4-round1 d a b c (aref m 5) 7 '(0 . 0))
c (md4-round1 c d a b (aref m 6) 11 '(0 . 0))
b (md4-round1 b c d a (aref m 7) 19 '(0 . 0))
a (md4-round1 a b c d (aref m 8) 3 '(0 . 0))
d (md4-round1 d a b c (aref m 9) 7 '(0 . 0))
c (md4-round1 c d a b (aref m 10) 11 '(0 . 0))
b (md4-round1 b c d a (aref m 11) 19 '(0 . 0))
a (md4-round1 a b c d (aref m 12) 3 '(0 . 0))
d (md4-round1 d a b c (aref m 13) 7 '(0 . 0))
c (md4-round1 c d a b (aref m 14) 11 '(0 . 0))
b (md4-round1 b c d a (aref m 15) 19 '(0 . 0))
a (md4-round2 a b c d (aref m 0) 3 '(23170 . 31129)) ;0x5A827999
d (md4-round2 d a b c (aref m 4) 5 '(23170 . 31129))
c (md4-round2 c d a b (aref m 8) 9 '(23170 . 31129))
b (md4-round2 b c d a (aref m 12) 13 '(23170 . 31129))
a (md4-round2 a b c d (aref m 1) 3 '(23170 . 31129))
d (md4-round2 d a b c (aref m 5) 5 '(23170 . 31129))
c (md4-round2 c d a b (aref m 9) 9 '(23170 . 31129))
b (md4-round2 b c d a (aref m 13) 13 '(23170 . 31129))
a (md4-round2 a b c d (aref m 2) 3 '(23170 . 31129))
d (md4-round2 d a b c (aref m 6) 5 '(23170 . 31129))
c (md4-round2 c d a b (aref m 10) 9 '(23170 . 31129))
b (md4-round2 b c d a (aref m 14) 13 '(23170 . 31129))
a (md4-round2 a b c d (aref m 3) 3 '(23170 . 31129))
d (md4-round2 d a b c (aref m 7) 5 '(23170 . 31129))
c (md4-round2 c d a b (aref m 11) 9 '(23170 . 31129))
b (md4-round2 b c d a (aref m 15) 13 '(23170 . 31129))
a (md4-round3 a b c d (aref m 0) 3 '(28377 . 60321)) ;0x6ED9EBA1
d (md4-round3 d a b c (aref m 8) 9 '(28377 . 60321))
c (md4-round3 c d a b (aref m 4) 11 '(28377 . 60321))
b (md4-round3 b c d a (aref m 12) 15 '(28377 . 60321))
a (md4-round3 a b c d (aref m 2) 3 '(28377 . 60321))
d (md4-round3 d a b c (aref m 10) 9 '(28377 . 60321))
c (md4-round3 c d a b (aref m 6) 11 '(28377 . 60321))
b (md4-round3 b c d a (aref m 14) 15 '(28377 . 60321))
a (md4-round3 a b c d (aref m 1) 3 '(28377 . 60321))
d (md4-round3 d a b c (aref m 9) 9 '(28377 . 60321))
c (md4-round3 c d a b (aref m 5) 11 '(28377 . 60321))
b (md4-round3 b c d a (aref m 13) 15 '(28377 . 60321))
a (md4-round3 a b c d (aref m 3) 3 '(28377 . 60321))
d (md4-round3 d a b c (aref m 11) 9 '(28377 . 60321))
c (md4-round3 c d a b (aref m 7) 11 '(28377 . 60321))
b (md4-round3 b c d a (aref m 15) 15 '(28377 . 60321)))
(aset md4-buffer 0 (md4-add a (aref md4-buffer 0)))
(aset md4-buffer 1 (md4-add b (aref md4-buffer 1)))
(aset md4-buffer 2 (md4-add c (aref md4-buffer 2)))
(aset md4-buffer 3 (md4-add d (aref md4-buffer 3)))
))
(defun md4-copy64 (seq)
"Unpack a 64 bytes string into 16 pairs of 32 bits integers."
(let ((int32s (make-vector 16 0)) (i 0) j)
(while (< i 16)
(setq j (* i 4))
(aset int32s i (cons (+ (aref seq (+ j 2)) (ash (aref seq (+ j 3)) 8))
(+ (aref seq j) (ash (aref seq (1+ j)) 8))))
(setq i (1+ i)))
int32s))
;;;
;;; sub functions
(defun md4-pack-int16 (int16)
"Pack 16 bits integer in 2 bytes string as little endian."
(let ((str (make-string 2 0)))
(aset str 0 (logand int16 255))
(aset str 1 (ash int16 -8))
str))
(defun md4-pack-int32 (int32)
"Pack 32 bits integer in a 4 bytes string as little endian.
A 32 bits integer is represented as a pair of two 16 bits
integers (cons high low)."
(let ((str (make-string 4 0))
(h (car int32)) (l (cdr int32)))
(aset str 0 (logand l 255))
(aset str 1 (ash l -8))
(aset str 2 (logand h 255))
(aset str 3 (ash h -8))
str))
(defun md4-unpack-int16 (str)
(if (eq 2 (length str))
(+ (ash (aref str 1) 8) (aref str 0))
(error "%s is not 2 bytes long" str)))
(defun md4-unpack-int32 (str)
(if (eq 4 (length str))
(cons (+ (ash (aref str 3) 8) (aref str 2))
(+ (ash (aref str 1) 8) (aref str 0)))
(error "%s is not 4 bytes long" str)))
(provide 'md4)
;;; md4.el ends here
|
