379 lines
9.5 KiB
C
379 lines
9.5 KiB
C
/* idea.c - IDEA function
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* Copyright 1997, 1998, 1999, 2001 Werner Koch (dd9jn)
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* Copyright 2013 g10 Code GmbH
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* WERNER KOCH BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* Except as contained in this notice, the name of Werner Koch shall not be
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* used in advertising or otherwise to promote the sale, use or other dealings
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* in this Software without prior written authorization from Werner Koch.
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*
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* Patents on IDEA have expired:
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* Europe: EP0482154 on 2011-05-16,
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* Japan: JP3225440 on 2011-05-16,
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* U.S.: 5,214,703 on 2012-01-07.
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*/
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/*
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* Please see http://www.noepatents.org/ to learn why software patents
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* are bad for society and what you can do to fight them.
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*
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* The code herein is based on the one from:
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* Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1996.
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* ISBN 0-471-11709-9.
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include "types.h" /* for byte and u32 typedefs */
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#include "g10lib.h"
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#include "cipher.h"
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#define IDEA_KEYSIZE 16
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#define IDEA_BLOCKSIZE 8
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#define IDEA_ROUNDS 8
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#define IDEA_KEYLEN (6*IDEA_ROUNDS+4)
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typedef struct {
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u16 ek[IDEA_KEYLEN];
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u16 dk[IDEA_KEYLEN];
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int have_dk;
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} IDEA_context;
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static const char *selftest(void);
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static u16
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mul_inv( u16 x )
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{
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u16 t0, t1;
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u16 q, y;
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if( x < 2 )
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return x;
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t1 = 0x10001L / x;
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y = 0x10001L % x;
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if( y == 1 )
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return (1-t1) & 0xffff;
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t0 = 1;
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do {
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q = x / y;
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x = x % y;
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t0 += q * t1;
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if( x == 1 )
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return t0;
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q = y / x;
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y = y % x;
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t1 += q * t0;
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} while( y != 1 );
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return (1-t1) & 0xffff;
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}
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static void
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expand_key( const byte *userkey, u16 *ek )
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{
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int i,j;
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for(j=0; j < 8; j++ ) {
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ek[j] = (*userkey << 8) + userkey[1];
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userkey += 2;
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}
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for(i=0; j < IDEA_KEYLEN; j++ ) {
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i++;
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ek[i+7] = ek[i&7] << 9 | ek[(i+1)&7] >> 7;
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ek += i & 8;
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i &= 7;
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}
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}
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static void
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invert_key( u16 *ek, u16 dk[IDEA_KEYLEN] )
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{
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int i;
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u16 t1, t2, t3;
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u16 temp[IDEA_KEYLEN];
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u16 *p = temp + IDEA_KEYLEN;
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t1 = mul_inv( *ek++ );
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t2 = -*ek++;
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t3 = -*ek++;
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*--p = mul_inv( *ek++ );
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*--p = t3;
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*--p = t2;
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*--p = t1;
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for(i=0; i < IDEA_ROUNDS-1; i++ ) {
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t1 = *ek++;
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*--p = *ek++;
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*--p = t1;
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t1 = mul_inv( *ek++ );
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t2 = -*ek++;
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t3 = -*ek++;
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*--p = mul_inv( *ek++ );
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*--p = t2;
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*--p = t3;
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*--p = t1;
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}
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t1 = *ek++;
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*--p = *ek++;
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*--p = t1;
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t1 = mul_inv( *ek++ );
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t2 = -*ek++;
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t3 = -*ek++;
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*--p = mul_inv( *ek++ );
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*--p = t3;
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*--p = t2;
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*--p = t1;
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memcpy(dk, temp, sizeof(temp) );
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memset(temp, 0, sizeof(temp) ); /* burn temp */
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}
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static void
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cipher( byte *outbuf, const byte *inbuf, u16 *key )
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{
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u16 s2, s3;
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u16 in[4];
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int r = IDEA_ROUNDS;
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#define x1 (in[0])
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#define x2 (in[1])
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#define x3 (in[2])
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#define x4 (in[3])
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#define MUL(x,y) \
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do {u16 _t16; u32 _t32; \
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if( (_t16 = (y)) ) { \
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if( (x = (x)&0xffff) ) { \
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_t32 = (u32)x * _t16; \
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x = _t32 & 0xffff; \
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_t16 = _t32 >> 16; \
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x = ((x)-_t16) + (x<_t16?1:0); \
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} \
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else { \
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x = 1 - _t16; \
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} \
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} \
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else { \
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x = 1 - x; \
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} \
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} while(0)
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memcpy (in, inbuf, sizeof in);
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#ifndef WORDS_BIGENDIAN
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x1 = (x1>>8) | (x1<<8);
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x2 = (x2>>8) | (x2<<8);
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x3 = (x3>>8) | (x3<<8);
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x4 = (x4>>8) | (x4<<8);
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#endif
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do {
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MUL(x1, *key++);
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x2 += *key++;
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x3 += *key++;
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MUL(x4, *key++ );
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s3 = x3;
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x3 ^= x1;
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MUL(x3, *key++);
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s2 = x2;
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x2 ^=x4;
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x2 += x3;
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MUL(x2, *key++);
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x3 += x2;
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x1 ^= x2;
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x4 ^= x3;
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x2 ^= s3;
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x3 ^= s2;
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} while( --r );
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MUL(x1, *key++);
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x3 += *key++;
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x2 += *key++;
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MUL(x4, *key);
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#ifndef WORDS_BIGENDIAN
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x1 = (x1>>8) | (x1<<8);
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x2 = (x2>>8) | (x2<<8);
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x3 = (x3>>8) | (x3<<8);
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x4 = (x4>>8) | (x4<<8);
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#endif
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memcpy (outbuf+0, &x1, 2);
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memcpy (outbuf+2, &x3, 2);
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memcpy (outbuf+4, &x2, 2);
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memcpy (outbuf+6, &x4, 2);
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#undef MUL
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#undef x1
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#undef x2
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#undef x3
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#undef x4
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}
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static int
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do_setkey( IDEA_context *c, const byte *key, unsigned int keylen )
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{
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static int initialized = 0;
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static const char *selftest_failed = 0;
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if( !initialized ) {
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initialized = 1;
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selftest_failed = selftest();
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if( selftest_failed )
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log_error( "%s\n", selftest_failed );
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}
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if( selftest_failed )
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return GPG_ERR_SELFTEST_FAILED;
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assert(keylen == 16);
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c->have_dk = 0;
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expand_key( key, c->ek );
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invert_key( c->ek, c->dk );
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return 0;
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}
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static gcry_err_code_t
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idea_setkey (void *context, const byte *key, unsigned int keylen)
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{
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IDEA_context *ctx = context;
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int rc = do_setkey (ctx, key, keylen);
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_gcry_burn_stack (23+6*sizeof(void*));
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return rc;
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}
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static void
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encrypt_block( IDEA_context *c, byte *outbuf, const byte *inbuf )
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{
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cipher( outbuf, inbuf, c->ek );
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}
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static void
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idea_encrypt (void *context, byte *out, const byte *in)
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{
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IDEA_context *ctx = context;
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encrypt_block (ctx, out, in);
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_gcry_burn_stack (24+3*sizeof (void*));
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}
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static void
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decrypt_block( IDEA_context *c, byte *outbuf, const byte *inbuf )
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{
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if( !c->have_dk ) {
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c->have_dk = 1;
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invert_key( c->ek, c->dk );
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}
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cipher( outbuf, inbuf, c->dk );
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}
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static void
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idea_decrypt (void *context, byte *out, const byte *in)
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{
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IDEA_context *ctx = context;
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decrypt_block (ctx, out, in);
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_gcry_burn_stack (24+3*sizeof (void*));
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}
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static const char *
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selftest( void )
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{
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static struct {
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byte key[16];
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byte plain[8];
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byte cipher[8];
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} test_vectors[] = {
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{ { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
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0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
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{ 0x00, 0x00, 0x00, 0x01, 0x00, 0x02, 0x00, 0x03 },
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{ 0x11, 0xFB, 0xED, 0x2B, 0x01, 0x98, 0x6D, 0xE5 } },
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{ { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
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0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
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{ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 },
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{ 0x54, 0x0E, 0x5F, 0xEA, 0x18, 0xC2, 0xF8, 0xB1 } },
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{ { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
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0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
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{ 0x00, 0x19, 0x32, 0x4B, 0x64, 0x7D, 0x96, 0xAF },
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{ 0x9F, 0x0A, 0x0A, 0xB6, 0xE1, 0x0C, 0xED, 0x78 } },
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{ { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
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0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
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{ 0xF5, 0x20, 0x2D, 0x5B, 0x9C, 0x67, 0x1B, 0x08 },
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{ 0xCF, 0x18, 0xFD, 0x73, 0x55, 0xE2, 0xC5, 0xC5 } },
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{ { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
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0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
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{ 0xFA, 0xE6, 0xD2, 0xBE, 0xAA, 0x96, 0x82, 0x6E },
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{ 0x85, 0xDF, 0x52, 0x00, 0x56, 0x08, 0x19, 0x3D } },
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{ { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
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0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
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{ 0x0A, 0x14, 0x1E, 0x28, 0x32, 0x3C, 0x46, 0x50 },
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{ 0x2F, 0x7D, 0xE7, 0x50, 0x21, 0x2F, 0xB7, 0x34 } },
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{ { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
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0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
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{ 0x05, 0x0A, 0x0F, 0x14, 0x19, 0x1E, 0x23, 0x28 },
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{ 0x7B, 0x73, 0x14, 0x92, 0x5D, 0xE5, 0x9C, 0x09 } },
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{ { 0x00, 0x05, 0x00, 0x0A, 0x00, 0x0F, 0x00, 0x14,
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0x00, 0x19, 0x00, 0x1E, 0x00, 0x23, 0x00, 0x28 },
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{ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 },
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{ 0x3E, 0xC0, 0x47, 0x80, 0xBE, 0xFF, 0x6E, 0x20 } },
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{ { 0x3A, 0x98, 0x4E, 0x20, 0x00, 0x19, 0x5D, 0xB3,
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0x2E, 0xE5, 0x01, 0xC8, 0xC4, 0x7C, 0xEA, 0x60 },
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{ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 },
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{ 0x97, 0xBC, 0xD8, 0x20, 0x07, 0x80, 0xDA, 0x86 } },
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{ { 0x00, 0x64, 0x00, 0xC8, 0x01, 0x2C, 0x01, 0x90,
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0x01, 0xF4, 0x02, 0x58, 0x02, 0xBC, 0x03, 0x20 },
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{ 0x05, 0x32, 0x0A, 0x64, 0x14, 0xC8, 0x19, 0xFA },
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{ 0x65, 0xBE, 0x87, 0xE7, 0xA2, 0x53, 0x8A, 0xED } },
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{ { 0x9D, 0x40, 0x75, 0xC1, 0x03, 0xBC, 0x32, 0x2A,
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0xFB, 0x03, 0xE7, 0xBE, 0x6A, 0xB3, 0x00, 0x06 },
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{ 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08 },
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{ 0xF5, 0xDB, 0x1A, 0xC4, 0x5E, 0x5E, 0xF9, 0xF9 } }
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};
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IDEA_context c;
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byte buffer[8];
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int i;
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for(i=0; i < DIM(test_vectors); i++ ) {
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do_setkey( &c, test_vectors[i].key, 16 );
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encrypt_block( &c, buffer, test_vectors[i].plain );
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if( memcmp( buffer, test_vectors[i].cipher, 8 ) )
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return "IDEA test encryption failed.";
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decrypt_block( &c, buffer, test_vectors[i].cipher );
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if( memcmp( buffer, test_vectors[i].plain, 8 ) )
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return "IDEA test decryption failed.";
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}
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return NULL;
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}
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gcry_cipher_spec_t _gcry_cipher_spec_idea =
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{
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"IDEA", NULL, NULL, IDEA_BLOCKSIZE, 128,
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sizeof (IDEA_context),
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idea_setkey, idea_encrypt, idea_decrypt
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};
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