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+/* idea.c - IDEA function
+ * Copyright (c) 1997, 1998, 1999, 2001 by Werner Koch (dd9jn)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * WERNER KOCH BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Except as contained in this notice, the name of Werner Koch shall not be
+ * used in advertising or otherwise to promote the sale, use or other dealings
+ * in this Software without prior written authorization from Werner Koch.
+ *
+ * Patents on IDEA have expired:
+ * Europe: EP0482154 on 2011-05-16,
+ * Japan: JP3225440 on 2011-05-16,
+ * U.S.: 5,214,703 on 2012-01-07.
+ */
+
+/*
+ * Please see http://www.noepatents.org/ to learn why software patents
+ * are bad for society and what you can do to fight them.
+ *
+ * The code herein is based on the one from:
+ * Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1996.
+ * ISBN 0-471-11709-9.
+ */
+
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include "types.h" /* for byte and u32 typedefs */
+#include "util.h"
+#include "errors.h"
+#include "algorithms.h"
+
+
+#define FNCCAST_SETKEY(f) ((int(*)(void*, byte*, unsigned int))(f))
+#define FNCCAST_CRYPT(f) ((void(*)(void*, byte*, byte*))(f))
+
+#define CIPHER_ALGO_IDEA 1
+
+#define IDEA_KEYSIZE 16
+#define IDEA_BLOCKSIZE 8
+#define IDEA_ROUNDS 8
+#define IDEA_KEYLEN (6*IDEA_ROUNDS+4)
+
+typedef struct {
+ u16 ek[IDEA_KEYLEN];
+ u16 dk[IDEA_KEYLEN];
+ int have_dk;
+} IDEA_context;
+
+static const char *selftest(void);
+
+static void
+burn_stack (int bytes)
+{
+ char buf[64];
+
+ wipememory(buf,sizeof buf);
+ bytes -= sizeof buf;
+ if (bytes > 0)
+ burn_stack (bytes);
+}
+
+
+static u16
+mul_inv( u16 x )
+{
+ u16 t0, t1;
+ u16 q, y;
+
+ if( x < 2 )
+ return x;
+ t1 = 0x10001L / x;
+ y = 0x10001L % x;
+ if( y == 1 )
+ return (1-t1) & 0xffff;
+
+ t0 = 1;
+ do {
+ q = x / y;
+ x = x % y;
+ t0 += q * t1;
+ if( x == 1 )
+ return t0;
+ q = y / x;
+ y = y % x;
+ t1 += q * t0;
+ } while( y != 1 );
+ return (1-t1) & 0xffff;
+}
+
+
+
+static void
+expand_key( const byte *userkey, u16 *ek )
+{
+ int i,j;
+
+ for(j=0; j < 8; j++ ) {
+ ek[j] = (*userkey << 8) + userkey[1];
+ userkey += 2;
+ }
+ for(i=0; j < IDEA_KEYLEN; j++ ) {
+ i++;
+ ek[i+7] = ek[i&7] << 9 | ek[(i+1)&7] >> 7;
+ ek += i & 8;
+ i &= 7;
+ }
+}
+
+
+static void
+invert_key( u16 *ek, u16 dk[IDEA_KEYLEN] )
+{
+ int i;
+ u16 t1, t2, t3;
+ u16 temp[IDEA_KEYLEN];
+ u16 *p = temp + IDEA_KEYLEN;
+
+ t1 = mul_inv( *ek++ );
+ t2 = -*ek++;
+ t3 = -*ek++;
+ *--p = mul_inv( *ek++ );
+ *--p = t3;
+ *--p = t2;
+ *--p = t1;
+
+ for(i=0; i < IDEA_ROUNDS-1; i++ ) {
+ t1 = *ek++;
+ *--p = *ek++;
+ *--p = t1;
+
+ t1 = mul_inv( *ek++ );
+ t2 = -*ek++;
+ t3 = -*ek++;
+ *--p = mul_inv( *ek++ );
+ *--p = t2;
+ *--p = t3;
+ *--p = t1;
+ }
+ t1 = *ek++;
+ *--p = *ek++;
+ *--p = t1;
+
+ t1 = mul_inv( *ek++ );
+ t2 = -*ek++;
+ t3 = -*ek++;
+ *--p = mul_inv( *ek++ );
+ *--p = t3;
+ *--p = t2;
+ *--p = t1;
+ memcpy(dk, temp, sizeof(temp) );
+ wipememory(temp, sizeof(temp) ); /* burn temp */
+}
+
+
+static void
+cipher( byte *outbuf, const byte *inbuf, u16 *key )
+{
+ u16 x1, x2, x3,x4, s2, s3;
+ u16 *in, *out;
+ int r = IDEA_ROUNDS;
+ #define MUL(x,y) \
+ do {u16 _t16; u32 _t32; \
+ if( (_t16 = (y)) ) { \
+ if( (x = (x)&0xffff) ) { \
+ _t32 = (u32)x * _t16; \
+ x = _t32 & 0xffff; \
+ _t16 = _t32 >> 16; \
+ x = ((x)-_t16) + (x<_t16?1:0); \
+ } \
+ else { \
+ x = 1 - _t16; \
+ } \
+ } \
+ else { \
+ x = 1 - x; \
+ } \
+ } while(0)
+
+ in = (u16*)inbuf;
+ x1 = *in++;
+ x2 = *in++;
+ x3 = *in++;
+ x4 = *in;
+ #ifndef WORDS_BIGENDIAN
+ x1 = (x1>>8) | (x1<<8);
+ x2 = (x2>>8) | (x2<<8);
+ x3 = (x3>>8) | (x3<<8);
+ x4 = (x4>>8) | (x4<<8);
+ #endif
+ do {
+ MUL(x1, *key++);
+ x2 += *key++;
+ x3 += *key++;
+ MUL(x4, *key++ );
+
+ s3 = x3;
+ x3 ^= x1;
+ MUL(x3, *key++);
+ s2 = x2;
+ x2 ^=x4;
+ x2 += x3;
+ MUL(x2, *key++);
+ x3 += x2;
+
+ x1 ^= x2;
+ x4 ^= x3;
+
+ x2 ^= s3;
+ x3 ^= s2;
+ } while( --r );
+ MUL(x1, *key++);
+ x3 += *key++;
+ x2 += *key++;
+ MUL(x4, *key);
+
+ out = (u16*)outbuf;
+ #ifndef WORDS_BIGENDIAN
+ *out++ = (x1>>8) | (x1<<8);
+ *out++ = (x3>>8) | (x3<<8);
+ *out++ = (x2>>8) | (x2<<8);
+ *out = (x4>>8) | (x4<<8);
+ #else
+ *out++ = x1;
+ *out++ = x3;
+ *out++ = x2;
+ *out = x4;
+ #endif
+ #undef MUL
+}
+
+
+static int
+do_setkey( IDEA_context *c, const byte *key, unsigned int keylen )
+{
+ static int initialized = 0;
+ static const char *selftest_failed = 0;
+
+ if( !initialized ) {
+ initialized = 1;
+ selftest_failed = selftest();
+ if( selftest_failed )
+ log_error( "%s\n", selftest_failed );
+ }
+ if( selftest_failed )
+ return G10ERR_SELFTEST_FAILED;
+
+ assert(keylen == 16);
+ c->have_dk = 0;
+ expand_key( key, c->ek );
+ invert_key( c->ek, c->dk );
+ return 0;
+}
+
+static int
+idea_setkey (void *context, const byte *key, unsigned int keylen)
+{
+ IDEA_context *ctx = context;
+ int rc = do_setkey (ctx, key, keylen);
+ burn_stack (23+6*sizeof(void*));
+ return rc;
+}
+
+static void
+encrypt_block( IDEA_context *c, byte *outbuf, const byte *inbuf )
+{
+ cipher( outbuf, inbuf, c->ek );
+}
+
+static void
+idea_encrypt (void *context, byte *out, const byte *in)
+{
+ IDEA_context *ctx = context;
+ encrypt_block (ctx, out, in);
+ burn_stack (24+3*sizeof (void*));
+}
+
+static void
+decrypt_block( IDEA_context *c, byte *outbuf, const byte *inbuf )
+{
+ if( !c->have_dk ) {
+ c->have_dk = 1;
+ invert_key( c->ek, c->dk );
+ }
+ cipher( outbuf, inbuf, c->dk );
+}
+
+static void
+idea_decrypt (void *context, byte *out, const byte *in)
+{
+ IDEA_context *ctx = context;
+ decrypt_block (ctx, out, in);
+ burn_stack (24+3*sizeof (void*));
+}
+
+
+static const char *
+selftest( void )
+{
+static struct {
+ byte key[16];
+ byte plain[8];
+ byte cipher[8];
+} test_vectors[] = {
+ { { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
+ 0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
+ { 0x00, 0x00, 0x00, 0x01, 0x00, 0x02, 0x00, 0x03 },
+ { 0x11, 0xFB, 0xED, 0x2B, 0x01, 0x98, 0x6D, 0xE5 } },
+ { { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
+ 0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
+ { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 },
+ { 0x54, 0x0E, 0x5F, 0xEA, 0x18, 0xC2, 0xF8, 0xB1 } },
+ { { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
+ 0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
+ { 0x00, 0x19, 0x32, 0x4B, 0x64, 0x7D, 0x96, 0xAF },
+ { 0x9F, 0x0A, 0x0A, 0xB6, 0xE1, 0x0C, 0xED, 0x78 } },
+ { { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
+ 0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
+ { 0xF5, 0x20, 0x2D, 0x5B, 0x9C, 0x67, 0x1B, 0x08 },
+ { 0xCF, 0x18, 0xFD, 0x73, 0x55, 0xE2, 0xC5, 0xC5 } },
+ { { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
+ 0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
+ { 0xFA, 0xE6, 0xD2, 0xBE, 0xAA, 0x96, 0x82, 0x6E },
+ { 0x85, 0xDF, 0x52, 0x00, 0x56, 0x08, 0x19, 0x3D } },
+ { { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
+ 0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
+ { 0x0A, 0x14, 0x1E, 0x28, 0x32, 0x3C, 0x46, 0x50 },
+ { 0x2F, 0x7D, 0xE7, 0x50, 0x21, 0x2F, 0xB7, 0x34 } },
+ { { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
+ 0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 },
+ { 0x05, 0x0A, 0x0F, 0x14, 0x19, 0x1E, 0x23, 0x28 },
+ { 0x7B, 0x73, 0x14, 0x92, 0x5D, 0xE5, 0x9C, 0x09 } },
+ { { 0x00, 0x05, 0x00, 0x0A, 0x00, 0x0F, 0x00, 0x14,
+ 0x00, 0x19, 0x00, 0x1E, 0x00, 0x23, 0x00, 0x28 },
+ { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 },
+ { 0x3E, 0xC0, 0x47, 0x80, 0xBE, 0xFF, 0x6E, 0x20 } },
+ { { 0x3A, 0x98, 0x4E, 0x20, 0x00, 0x19, 0x5D, 0xB3,
+ 0x2E, 0xE5, 0x01, 0xC8, 0xC4, 0x7C, 0xEA, 0x60 },
+ { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 },
+ { 0x97, 0xBC, 0xD8, 0x20, 0x07, 0x80, 0xDA, 0x86 } },
+ { { 0x00, 0x64, 0x00, 0xC8, 0x01, 0x2C, 0x01, 0x90,
+ 0x01, 0xF4, 0x02, 0x58, 0x02, 0xBC, 0x03, 0x20 },
+ { 0x05, 0x32, 0x0A, 0x64, 0x14, 0xC8, 0x19, 0xFA },
+ { 0x65, 0xBE, 0x87, 0xE7, 0xA2, 0x53, 0x8A, 0xED } },
+ { { 0x9D, 0x40, 0x75, 0xC1, 0x03, 0xBC, 0x32, 0x2A,
+ 0xFB, 0x03, 0xE7, 0xBE, 0x6A, 0xB3, 0x00, 0x06 },
+ { 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08 },
+ { 0xF5, 0xDB, 0x1A, 0xC4, 0x5E, 0x5E, 0xF9, 0xF9 } }
+};
+ IDEA_context c;
+ byte buffer[8];
+ int i;
+
+ for(i=0; i < DIM(test_vectors); i++ ) {
+ do_setkey( &c, test_vectors[i].key, 16 );
+ encrypt_block( &c, buffer, test_vectors[i].plain );
+ if( memcmp( buffer, test_vectors[i].cipher, 8 ) )
+ return "IDEA test encryption failed.";
+ decrypt_block( &c, buffer, test_vectors[i].cipher );
+ if( memcmp( buffer, test_vectors[i].plain, 8 ) )
+ return "IDEA test decryption failed.";
+ }
+
+ return NULL;
+}
+
+
+/****************
+ * Return some information about the algorithm. We need algo here to
+ * distinguish different flavors of the algorithm.
+ * Returns: A pointer to string describing the algorithm or NULL if
+ * the ALGO is invalid.
+ */
+const char *
+idea_get_info( int algo, size_t *keylen,
+ size_t *blocksize, size_t *contextsize,
+ int (**r_setkey)( void *c, const byte *key, unsigned keylen ),
+ void (**r_encrypt)( void *c, byte *outbuf, const byte *inbuf ),
+ void (**r_decrypt)( void *c, byte *outbuf, const byte *inbuf )
+ )
+{
+ *keylen = 128;
+ *blocksize = IDEA_BLOCKSIZE;
+ *contextsize = sizeof(IDEA_context);
+ *r_setkey = idea_setkey;
+ *r_encrypt = idea_encrypt;
+ *r_decrypt = idea_decrypt;
+
+ if( algo == CIPHER_ALGO_IDEA )
+ return "IDEA";
+ return NULL;
+}
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