twofish.cpp

TWOFISH加密算法

   INPACK (1, b, 1);
   INPACK (2, c, 2);
   INPACK (3, d, 3);

   /* Encryption Feistel cycles. */
   ENCCYCLE (0);
   ENCCYCLE (1);
   ENCCYCLE (2);
   ENCCYCLE (3);
   ENCCYCLE (4);
   ENCCYCLE (5);
   ENCCYCLE (6);
   ENCCYCLE (7);

   /* Output whitening and unpacking. */
   OUTUNPACK (0, c, 4);
   OUTUNPACK (1, d, 5);
   OUTUNPACK (2, a, 6);
   OUTUNPACK (3, b, 7);
}

void twofish_encrypt (void *ctx, byte *out, const byte *in)
{
    do_twofish_encrypt ((TWOFISH_context*)ctx, out, in);
    burn_stack (24+3*sizeof (void*));
}

/* Decrypt one block.  in and out may be the same. */

static void
do_twofish_decrypt (const TWOFISH_context *ctx, byte *out, const byte *in)
{
   /* The four 32-bit chunks of the text. */
   u32 a, b, c, d;

   /* Temporaries used by the round function. */
   u32 x, y;

   /* Input whitening and packing. */
   INPACK (0, c, 4);
   INPACK (1, d, 5);
   INPACK (2, a, 6);
   INPACK (3, b, 7);

   /* Encryption Feistel cycles. */
   DECCYCLE (7);
   DECCYCLE (6);
   DECCYCLE (5);
   DECCYCLE (4);
   DECCYCLE (3);
   DECCYCLE (2);
   DECCYCLE (1);
   DECCYCLE (0);

   /* Output whitening and unpacking. */
   OUTUNPACK (0, a, 0);
   OUTUNPACK (1, b, 1);
   OUTUNPACK (2, c, 2);
   OUTUNPACK (3, d, 3);
}

void twofish_decrypt (void *ctx, byte *out, const byte *in)
{
    do_twofish_decrypt ((TWOFISH_context*)ctx, out, in);
    burn_stack (24+3*sizeof (void*));
}

/* Test a single encryption and decryption with each key size. */

static const char*
selftest (void)
{
   TWOFISH_context ctx; /* Expanded key. */
   byte scratch[16];	/* Encryption/decryption result buffer. */

   /* Test vectors for single encryption/decryption.  Note that I am using
    * the vectors from the Twofish paper's "known answer test", I=3 for
    * 128-bit and I=4 for 256-bit, instead of the all-0 vectors from the
    * "intermediate value test", because an all-0 key would trigger all the
    * special cases in the RS matrix multiply, leaving the math untested. */
   static const byte plaintext[16] = {
      0xD4, 0x91, 0xDB, 0x16, 0xE7, 0xB1, 0xC3, 0x9E,
      0x86, 0xCB, 0x08, 0x6B, 0x78, 0x9F, 0x54, 0x19
   };
   static const byte key[16] = {
      0x9F, 0x58, 0x9F, 0x5C, 0xF6, 0x12, 0x2C, 0x32,
      0xB6, 0xBF, 0xEC, 0x2F, 0x2A, 0xE8, 0xC3, 0x5A
   };
   static const byte ciphertext[16] = {
      0x01, 0x9F, 0x98, 0x09, 0xDE, 0x17, 0x11, 0x85,
      0x8F, 0xAA, 0xC3, 0xA3, 0xBA, 0x20, 0xFB, 0xC3
   };
   static const byte plaintext_256[16] = {
      0x90, 0xAF, 0xE9, 0x1B, 0xB2, 0x88, 0x54, 0x4F,
      0x2C, 0x32, 0xDC, 0x23, 0x9B, 0x26, 0x35, 0xE6
   };
   static const byte key_256[32] = {
      0xD4, 0x3B, 0xB7, 0x55, 0x6E, 0xA3, 0x2E, 0x46,
      0xF2, 0xA2, 0x82, 0xB7, 0xD4, 0x5B, 0x4E, 0x0D,
      0x57, 0xFF, 0x73, 0x9D, 0x4D, 0xC9, 0x2C, 0x1B,
      0xD7, 0xFC, 0x01, 0x70, 0x0C, 0xC8, 0x21, 0x6F
   };
   static const byte ciphertext_256[16] = {
      0x6C, 0xB4, 0x56, 0x1C, 0x40, 0xBF, 0x0A, 0x97,
      0x05, 0x93, 0x1C, 0xB6, 0xD4, 0x08, 0xE7, 0xFA
   };

   twofish_setkey (&ctx, key, sizeof(key));
   twofish_encrypt (&ctx, scratch, plaintext);
   if (memcmp (scratch, ciphertext, sizeof (ciphertext)))
     return "Twofish-128 test encryption failed.";
   twofish_decrypt (&ctx, scratch, scratch);
   if (memcmp (scratch, plaintext, sizeof (plaintext)))
     return "Twofish-128 test decryption failed.";

   twofish_setkey (&ctx, key_256, sizeof(key_256));
   twofish_encrypt (&ctx, scratch, plaintext_256);
   if (memcmp (scratch, ciphertext_256, sizeof (ciphertext_256)))
     return "Twofish-256 test encryption failed.";
   twofish_decrypt (&ctx, scratch, scratch);
   if (memcmp (scratch, plaintext_256, sizeof (plaintext_256)))
     return "Twofish-256 test decryption failed.";

   return NULL;
}

/* More complete test program.	This does 1000 encryptions and decryptions
 * with each of 250 128-bit keys and 2000 encryptions and decryptions with
 * each of 125 256-bit keys, using a feedback scheme similar to a Feistel
 * cipher, so as to be sure of testing all the table entries pretty
 * thoroughly.	We keep changing the keys so as to get a more meaningful
 * performance number, since the key setup is non-trivial for Twofish. */

#ifdef TEST

#include <stdio.h>
#include <string.h>
#include <time.h>

int
main()
{
   TWOFISH_context ctx;     /* Expanded key. */
   int i, j;		    /* Loop counters. */

   const char *encrypt_msg; /* Message to print regarding encryption test;
			     * the printf is done outside the loop to avoid
			     * stuffing up the timing. */
   clock_t timer; /* For computing elapsed time. */

   /* Test buffer. */
   byte buffer[4][16] = {
      {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
       0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF},
      {0x0F, 0x1E, 0x2D, 0x3C, 0x4B, 0x5A, 0x69, 0x78,
       0x87, 0x96, 0xA5, 0xB4, 0xC3, 0xD2 ,0xE1, 0xF0},
      {0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF,
       0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54 ,0x32, 0x10},
      {0x01, 0x23, 0x45, 0x67, 0x76, 0x54 ,0x32, 0x10,
       0x89, 0xAB, 0xCD, 0xEF, 0xFE, 0xDC, 0xBA, 0x98}
   };

   /* Expected outputs for the million-operation test */
   static const byte test_encrypt[4][16] = {
      {0xC8, 0x23, 0xB8, 0xB7, 0x6B, 0xFE, 0x91, 0x13,
       0x2F, 0xA7, 0x5E, 0xE6, 0x94, 0x77, 0x6F, 0x6B},
      {0x90, 0x36, 0xD8, 0x29, 0xD5, 0x96, 0xC2, 0x8E,
       0xE4, 0xFF, 0x76, 0xBC, 0xE5, 0x77, 0x88, 0x27},
      {0xB8, 0x78, 0x69, 0xAF, 0x42, 0x8B, 0x48, 0x64,
       0xF7, 0xE9, 0xF3, 0x9C, 0x42, 0x18, 0x7B, 0x73},
      {0x7A, 0x88, 0xFB, 0xEB, 0x90, 0xA4, 0xB4, 0xA8,
       0x43, 0xA3, 0x1D, 0xF1, 0x26, 0xC4, 0x53, 0x57}
   };
   static const byte test_decrypt[4][16] = {
      {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
       0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF},
      {0x0F, 0x1E, 0x2D, 0x3C, 0x4B, 0x5A, 0x69, 0x78,
       0x87, 0x96, 0xA5, 0xB4, 0xC3, 0xD2 ,0xE1, 0xF0},
      {0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF,
       0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54 ,0x32, 0x10},
      {0x01, 0x23, 0x45, 0x67, 0x76, 0x54 ,0x32, 0x10,
       0x89, 0xAB, 0xCD, 0xEF, 0xFE, 0xDC, 0xBA, 0x98}
   };

   /* Start the timer ticking. */
   timer = clock ();

   /* Encryption test. */
   for (i = 0; i < 125; i++) {
      twofish_setkey (&ctx, buffer[0], sizeof (buffer[0]));
      for (j = 0; j < 1000; j++)
	twofish_encrypt (&ctx, buffer[2], buffer[2]);
      twofish_setkey (&ctx, buffer[1], sizeof (buffer[1]));
      for (j = 0; j < 1000; j++)
	twofish_encrypt (&ctx, buffer[3], buffer[3]);
      twofish_setkey (&ctx, buffer[2], sizeof (buffer[2])*2);
      for (j = 0; j < 1000; j++) {
	twofish_encrypt (&ctx, buffer[0], buffer[0]);
	twofish_encrypt (&ctx, buffer[1], buffer[1]);
      }
   }
   encrypt_msg = memcmp (buffer, test_encrypt, sizeof (test_encrypt)) ?
		 "encryption failure!\n" : "encryption OK!\n";

   /* Decryption test. */
   for (i = 0; i < 125; i++) {
      twofish_setkey (&ctx, buffer[2], sizeof (buffer[2])*2);
      for (j = 0; j < 1000; j++) {
	twofish_decrypt (&ctx, buffer[0], buffer[0]);
	twofish_decrypt (&ctx, buffer[1], buffer[1]);
      }
      twofish_setkey (&ctx, buffer[1], sizeof (buffer[1]));
      for (j = 0; j < 1000; j++)
	twofish_decrypt (&ctx, buffer[3], buffer[3]);
      twofish_setkey (&ctx, buffer[0], sizeof (buffer[0]));
      for (j = 0; j < 1000; j++)
	twofish_decrypt (&ctx, buffer[2], buffer[2]);
   }

   /* Stop the timer, and print results. */
   timer = clock () - timer;
   printf (encrypt_msg);
   printf (memcmp (buffer, test_decrypt, sizeof (test_decrypt)) ?
	   "decryption failure!\n" : "decryption OK!\n");
   printf ("elapsed time: %.1f s.\n", (float) timer / CLOCKS_PER_SEC);

   return 0;
}

#endif /* TEST */

const char *
twofish_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 = algo==10? 256 : 128;
    *blocksize = 16;
    *contextsize = sizeof (TWOFISH_context);

    *r_setkey = twofish_setkey;
    *r_encrypt = twofish_encrypt;
    *r_decrypt = twofish_decrypt;

    if( algo == 10 )
	return "TWOFISH";
    if (algo == 102) /* This algorithm number is assigned for
		      * experiments, so we can use it */
	return "TWOFISH128";
    return NULL;
}