rc6.c - third_party/dropbear - Git at Google

 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
  *
  * LibTomCrypt is a library that provides various cryptographic
  * algorithms in a highly modular and flexible manner.
  *
  * The library is free for all purposes without any express
  * guarantee it works.
  *
  * Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
  */

 /* RC6 code by Tom St Denis */
 #include "mycrypt.h"

 #ifdef RC6

 const struct _cipher_descriptor rc6_desc =
 {
     "rc6",
     3,
     8, 128, 16, 20,
     &rc6_setup,
     &rc6_ecb_encrypt,
     &rc6_ecb_decrypt,
     &rc6_test,
     &rc6_keysize
 };

 static const ulong32 stab[44] = {
 0xb7e15163UL, 0x5618cb1cUL, 0xf45044d5UL, 0x9287be8eUL, 0x30bf3847UL, 0xcef6b200UL, 0x6d2e2bb9UL, 0x0b65a572UL,
 0xa99d1f2bUL, 0x47d498e4UL, 0xe60c129dUL, 0x84438c56UL, 0x227b060fUL, 0xc0b27fc8UL, 0x5ee9f981UL, 0xfd21733aUL,
 0x9b58ecf3UL, 0x399066acUL, 0xd7c7e065UL, 0x75ff5a1eUL, 0x1436d3d7UL, 0xb26e4d90UL, 0x50a5c749UL, 0xeedd4102UL,
 0x8d14babbUL, 0x2b4c3474UL, 0xc983ae2dUL, 0x67bb27e6UL, 0x05f2a19fUL, 0xa42a1b58UL, 0x42619511UL, 0xe0990ecaUL,
 0x7ed08883UL, 0x1d08023cUL, 0xbb3f7bf5UL, 0x5976f5aeUL, 0xf7ae6f67UL, 0x95e5e920UL, 0x341d62d9UL, 0xd254dc92UL,
 0x708c564bUL, 0x0ec3d004UL, 0xacfb49bdUL, 0x4b32c376UL };

 #ifdef CLEAN_STACK
 static int _rc6_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
 #else
 int rc6_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
 #endif
 {
     ulong32 L[64], S[50], A, B, i, j, v, s, l;

     _ARGCHK(key != NULL);
     _ARGCHK(skey != NULL);

     /* test parameters */
     if (num_rounds != 0 && num_rounds != 20) {
        return CRYPT_INVALID_ROUNDS;
     }

     /* key must be between 64 and 1024 bits */
     if (keylen < 8 || keylen > 128) {
        return CRYPT_INVALID_KEYSIZE;
     }

     /* copy the key into the L array */
     for (A = i = j = 0; i < (ulong32)keylen; ) {
         A = (A << 8) | ((ulong32)(key[i++] & 255));
         if (!(i & 3)) {
            L[j++] = BSWAP(A);
            A = 0;
         }
     }

     /* handle odd sized keys */
     if (keylen & 3) {
        A <<= (8 * (4 - (keylen&3)));
        L[j++] = BSWAP(A);
     }

     /* setup the S array */
     XMEMCPY(S, stab, 44 * sizeof(stab[0]));

     /* mix buffer */
     s = 3 * MAX(44, j);
     l = j;
     for (A = B = i = j = v = 0; v < s; v++) {
         A = S[i] = ROL(S[i] + A + B, 3);
         B = L[j] = ROL(L[j] + A + B, (A+B));
         if (++i == 44) { i = 0; }
         if (++j == l)  { j = 0; }
     }

     /* copy to key */
     for (i = 0; i < 44; i++) {
         skey->rc6.K[i] = S[i];
     }
     return CRYPT_OK;
 }

 #ifdef CLEAN_STACK
 int rc6_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
 {
    int x;
    x = _rc6_setup(key, keylen, num_rounds, skey);
    burn_stack(sizeof(ulong32) * 122);
    return x;
 }
 #endif

 #ifdef CLEAN_STACK
 static void _rc6_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
 #else
 void rc6_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
 #endif
 {
    ulong32 a,b,c,d,t,u, *K;
    int r;

    _ARGCHK(key != NULL);
    _ARGCHK(pt != NULL);
    _ARGCHK(ct != NULL);
    LOAD32L(a,&pt[0]);LOAD32L(b,&pt[4]);LOAD32L(c,&pt[8]);LOAD32L(d,&pt[12]);

    b += key->rc6.K[0];
    d += key->rc6.K[1];

 #define RND(a,b,c,d) \
        t = (b * (b + b + 1)); t = ROL(t, 5); \
        u = (d * (d + d + 1)); u = ROL(u, 5); \
        a = ROL(a^t,u) + K[0];                \
        c = ROL(c^u,t) + K[1]; K += 2;

    K = key->rc6.K + 2;
    for (r = 0; r < 20; r += 4) {
        RND(a,b,c,d);
        RND(b,c,d,a);
        RND(c,d,a,b);
        RND(d,a,b,c);
    }

 #undef RND

    a += key->rc6.K[42];
    c += key->rc6.K[43];
    STORE32L(a,&ct[0]);STORE32L(b,&ct[4]);STORE32L(c,&ct[8]);STORE32L(d,&ct[12]);
 }

 #ifdef CLEAN_STACK
 void rc6_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
 {
    _rc6_ecb_encrypt(pt, ct, key);
    burn_stack(sizeof(ulong32) * 6 + sizeof(int));
 }
 #endif

 #ifdef CLEAN_STACK
 static void _rc6_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
 #else
 void rc6_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
 #endif
 {
    ulong32 a,b,c,d,t,u, *K;
    int r;

    _ARGCHK(key != NULL);
    _ARGCHK(pt != NULL);
    _ARGCHK(ct != NULL);

    LOAD32L(a,&ct[0]);LOAD32L(b,&ct[4]);LOAD32L(c,&ct[8]);LOAD32L(d,&ct[12]);
    a -= key->rc6.K[42];
    c -= key->rc6.K[43];

 #define RND(a,b,c,d) \
        t = (b * (b + b + 1)); t = ROL(t, 5); \
        u = (d * (d + d + 1)); u = ROL(u, 5); \
        c = ROR(c - K[1], t) ^ u; \
        a = ROR(a - K[0], u) ^ t; K -= 2;

    K = key->rc6.K + 40;

    for (r = 0; r < 20; r += 4) {
        RND(d,a,b,c);
        RND(c,d,a,b);
        RND(b,c,d,a);
        RND(a,b,c,d);
    }

 #undef RND

    b -= key->rc6.K[0];
    d -= key->rc6.K[1];
    STORE32L(a,&pt[0]);STORE32L(b,&pt[4]);STORE32L(c,&pt[8]);STORE32L(d,&pt[12]);
 }

 #ifdef CLEAN_STACK
 void rc6_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
 {
    _rc6_ecb_decrypt(ct, pt, key);
    burn_stack(sizeof(ulong32) * 6 + sizeof(int));
 }
 #endif

 int rc6_test(void)
 {
  #ifndef LTC_TEST
     return CRYPT_NOP;
  #else
    static const struct {
        int keylen;
        unsigned char key[32], pt[16], ct[16];
    } tests[] = {
    {
        16,
        { 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
          0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
        { 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,
          0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },
        { 0x52, 0x4e, 0x19, 0x2f, 0x47, 0x15, 0xc6, 0x23,
          0x1f, 0x51, 0xf6, 0x36, 0x7e, 0xa4, 0x3f, 0x18 }
    },
    {
        24,
        { 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
          0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
          0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,
          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
        { 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,
          0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },
        { 0x68, 0x83, 0x29, 0xd0, 0x19, 0xe5, 0x05, 0x04,
          0x1e, 0x52, 0xe9, 0x2a, 0xf9, 0x52, 0x91, 0xd4 }
    },
    {
        32,
        { 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
          0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
          0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,
          0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe },
        { 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,
          0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },
        { 0xc8, 0x24, 0x18, 0x16, 0xf0, 0xd7, 0xe4, 0x89,
          0x20, 0xad, 0x16, 0xa1, 0x67, 0x4e, 0x5d, 0x48 }
    }
    };
    unsigned char tmp[2][16];
    int x, y, err;
    symmetric_key key;

    for (x  = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
       /* setup key */
       if ((err = rc6_setup(tests[x].key, tests[x].keylen, 0, &key)) != CRYPT_OK) {
          return err;
       }

       /* encrypt and decrypt */
       rc6_ecb_encrypt(tests[x].pt, tmp[0], &key);
       rc6_ecb_decrypt(tmp[0], tmp[1], &key);

       /* compare */
       if (memcmp(tmp[0], tests[x].ct, 16) || memcmp(tmp[1], tests[x].pt, 16)) {
 #if 0
          printf("\n\nFailed test %d\n", x);
          if (memcmp(tmp[0], tests[x].ct, 16)) {
             printf("Ciphertext:  ");
             for (y = 0; y < 16; y++) printf("%02x ", tmp[0][y]);
             printf("\nExpected  :  ");
             for (y = 0; y < 16; y++) printf("%02x ", tests[x].ct[y]);
             printf("\n");
          }
          if (memcmp(tmp[1], tests[x].pt, 16)) {
             printf("Plaintext:  ");
             for (y = 0; y < 16; y++) printf("%02x ", tmp[0][y]);
             printf("\nExpected :  ");
             for (y = 0; y < 16; y++) printf("%02x ", tests[x].pt[y]);
             printf("\n");
          }
 #endif
          return CRYPT_FAIL_TESTVECTOR;
       }

       /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
       for (y = 0; y < 16; y++) tmp[0][y] = 0;
       for (y = 0; y < 1000; y++) rc6_ecb_encrypt(tmp[0], tmp[0], &key);
       for (y = 0; y < 1000; y++) rc6_ecb_decrypt(tmp[0], tmp[0], &key);
       for (y = 0; y < 16; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
    }
    return CRYPT_OK;
   #endif
 }

 int rc6_keysize(int *desired_keysize)
 {
    _ARGCHK(desired_keysize != NULL);
    if (*desired_keysize < 8) {
       return CRYPT_INVALID_KEYSIZE;
    } else if (*desired_keysize > 128) {
       *desired_keysize = 128;
    }
    return CRYPT_OK;
 }

 #endif /*RC6*/
	/* LibTomCrypt, modular cryptographic library -- Tom St Denis
	*
	* LibTomCrypt is a library that provides various cryptographic
	* algorithms in a highly modular and flexible manner.
	*
	* The library is free for all purposes without any express
	* guarantee it works.
	*
	* Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
	*/

	/* RC6 code by Tom St Denis */
	#include "mycrypt.h"

	#ifdef RC6

	const struct _cipher_descriptor rc6_desc =
	{
	"rc6",
	3,
	8, 128, 16, 20,
	&rc6_setup,
	&rc6_ecb_encrypt,
	&rc6_ecb_decrypt,
	&rc6_test,
	&rc6_keysize
	};

	static const ulong32 stab[44] = {
	0xb7e15163UL, 0x5618cb1cUL, 0xf45044d5UL, 0x9287be8eUL, 0x30bf3847UL, 0xcef6b200UL, 0x6d2e2bb9UL, 0x0b65a572UL,
	0xa99d1f2bUL, 0x47d498e4UL, 0xe60c129dUL, 0x84438c56UL, 0x227b060fUL, 0xc0b27fc8UL, 0x5ee9f981UL, 0xfd21733aUL,
	0x9b58ecf3UL, 0x399066acUL, 0xd7c7e065UL, 0x75ff5a1eUL, 0x1436d3d7UL, 0xb26e4d90UL, 0x50a5c749UL, 0xeedd4102UL,
	0x8d14babbUL, 0x2b4c3474UL, 0xc983ae2dUL, 0x67bb27e6UL, 0x05f2a19fUL, 0xa42a1b58UL, 0x42619511UL, 0xe0990ecaUL,
	0x7ed08883UL, 0x1d08023cUL, 0xbb3f7bf5UL, 0x5976f5aeUL, 0xf7ae6f67UL, 0x95e5e920UL, 0x341d62d9UL, 0xd254dc92UL,
	0x708c564bUL, 0x0ec3d004UL, 0xacfb49bdUL, 0x4b32c376UL };

	#ifdef CLEAN_STACK
	static int _rc6_setup(const unsigned char key, int keylen, int num_rounds, symmetric_key skey)
	#else
	int rc6_setup(const unsigned char key, int keylen, int num_rounds, symmetric_key skey)
	#endif
	{
	ulong32 L[64], S[50], A, B, i, j, v, s, l;

	_ARGCHK(key != NULL);
	_ARGCHK(skey != NULL);

	/* test parameters */
	if (num_rounds != 0 && num_rounds != 20) {
	return CRYPT_INVALID_ROUNDS;
	}

	/* key must be between 64 and 1024 bits */
	if (keylen < 8 \|\| keylen > 128) {
	return CRYPT_INVALID_KEYSIZE;
	}

	/* copy the key into the L array */
	for (A = i = j = 0; i < (ulong32)keylen; ) {
	A = (A << 8) \| ((ulong32)(key[i++] & 255));
	if (!(i & 3)) {
	L[j++] = BSWAP(A);
	A = 0;
	}
	}

	/* handle odd sized keys */
	if (keylen & 3) {
	A <<= (8 * (4 - (keylen&3)));
	L[j++] = BSWAP(A);
	}

	/* setup the S array */
	XMEMCPY(S, stab, 44 * sizeof(stab[0]));

	/* mix buffer */
	s = 3 * MAX(44, j);
	l = j;
	for (A = B = i = j = v = 0; v < s; v++) {
	A = S[i] = ROL(S[i] + A + B, 3);
	B = L[j] = ROL(L[j] + A + B, (A+B));
	if (++i == 44) { i = 0; }
	if (++j == l) { j = 0; }
	}

	/* copy to key */
	for (i = 0; i < 44; i++) {
	skey->rc6.K[i] = S[i];
	}
	return CRYPT_OK;
	}

	#ifdef CLEAN_STACK
	int rc6_setup(const unsigned char key, int keylen, int num_rounds, symmetric_key skey)
	{
	int x;
	x = _rc6_setup(key, keylen, num_rounds, skey);
	burn_stack(sizeof(ulong32) * 122);
	return x;
	}
	#endif

	#ifdef CLEAN_STACK
	static void _rc6_ecb_encrypt(const unsigned char pt, unsigned char ct, symmetric_key *key)
	#else
	void rc6_ecb_encrypt(const unsigned char pt, unsigned char ct, symmetric_key *key)
	#endif
	{
	ulong32 a,b,c,d,t,u, *K;
	int r;

	_ARGCHK(key != NULL);
	_ARGCHK(pt != NULL);
	_ARGCHK(ct != NULL);
	LOAD32L(a,&pt[0]);LOAD32L(b,&pt[4]);LOAD32L(c,&pt[8]);LOAD32L(d,&pt[12]);

	b += key->rc6.K[0];
	d += key->rc6.K[1];

	#define RND(a,b,c,d) \
	t = (b * (b + b + 1)); t = ROL(t, 5); \
	u = (d * (d + d + 1)); u = ROL(u, 5); \
	a = ROL(a^t,u) + K[0]; \
	c = ROL(c^u,t) + K[1]; K += 2;

	K = key->rc6.K + 2;
	for (r = 0; r < 20; r += 4) {
	RND(a,b,c,d);
	RND(b,c,d,a);
	RND(c,d,a,b);
	RND(d,a,b,c);
	}

	#undef RND

	a += key->rc6.K[42];
	c += key->rc6.K[43];
	STORE32L(a,&ct[0]);STORE32L(b,&ct[4]);STORE32L(c,&ct[8]);STORE32L(d,&ct[12]);
	}

	#ifdef CLEAN_STACK
	void rc6_ecb_encrypt(const unsigned char pt, unsigned char ct, symmetric_key *key)
	{
	_rc6_ecb_encrypt(pt, ct, key);
	burn_stack(sizeof(ulong32) * 6 + sizeof(int));
	}
	#endif

	#ifdef CLEAN_STACK
	static void _rc6_ecb_decrypt(const unsigned char ct, unsigned char pt, symmetric_key *key)
	#else
	void rc6_ecb_decrypt(const unsigned char ct, unsigned char pt, symmetric_key *key)
	#endif
	{
	ulong32 a,b,c,d,t,u, *K;
	int r;

	_ARGCHK(key != NULL);
	_ARGCHK(pt != NULL);
	_ARGCHK(ct != NULL);

	LOAD32L(a,&ct[0]);LOAD32L(b,&ct[4]);LOAD32L(c,&ct[8]);LOAD32L(d,&ct[12]);
	a -= key->rc6.K[42];
	c -= key->rc6.K[43];

	#define RND(a,b,c,d) \
	t = (b * (b + b + 1)); t = ROL(t, 5); \
	u = (d * (d + d + 1)); u = ROL(u, 5); \
	c = ROR(c - K[1], t) ^ u; \
	a = ROR(a - K[0], u) ^ t; K -= 2;

	K = key->rc6.K + 40;

	for (r = 0; r < 20; r += 4) {
	RND(d,a,b,c);
	RND(c,d,a,b);
	RND(b,c,d,a);
	RND(a,b,c,d);
	}

	#undef RND

	b -= key->rc6.K[0];
	d -= key->rc6.K[1];
	STORE32L(a,&pt[0]);STORE32L(b,&pt[4]);STORE32L(c,&pt[8]);STORE32L(d,&pt[12]);
	}

	#ifdef CLEAN_STACK
	void rc6_ecb_decrypt(const unsigned char ct, unsigned char pt, symmetric_key *key)
	{
	_rc6_ecb_decrypt(ct, pt, key);
	burn_stack(sizeof(ulong32) * 6 + sizeof(int));
	}
	#endif

	int rc6_test(void)
	{
	#ifndef LTC_TEST
	return CRYPT_NOP;
	#else
	static const struct {
	int keylen;
	unsigned char key[32], pt[16], ct[16];
	} tests[] = {
	{
	16,
	{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
	0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
	{ 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,
	0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },
	{ 0x52, 0x4e, 0x19, 0x2f, 0x47, 0x15, 0xc6, 0x23,
	0x1f, 0x51, 0xf6, 0x36, 0x7e, 0xa4, 0x3f, 0x18 }
	},
	{
	24,
	{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
	0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
	0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
	{ 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,
	0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },
	{ 0x68, 0x83, 0x29, 0xd0, 0x19, 0xe5, 0x05, 0x04,
	0x1e, 0x52, 0xe9, 0x2a, 0xf9, 0x52, 0x91, 0xd4 }
	},
	{
	32,
	{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
	0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
	0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,
	0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe },
	{ 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,
	0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },
	{ 0xc8, 0x24, 0x18, 0x16, 0xf0, 0xd7, 0xe4, 0x89,
	0x20, 0xad, 0x16, 0xa1, 0x67, 0x4e, 0x5d, 0x48 }
	}
	};
	unsigned char tmp[2][16];
	int x, y, err;
	symmetric_key key;

	for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
	/* setup key */
	if ((err = rc6_setup(tests[x].key, tests[x].keylen, 0, &key)) != CRYPT_OK) {
	return err;
	}

	/* encrypt and decrypt */
	rc6_ecb_encrypt(tests[x].pt, tmp[0], &key);
	rc6_ecb_decrypt(tmp[0], tmp[1], &key);

	/* compare */
	if (memcmp(tmp[0], tests[x].ct, 16) \|\| memcmp(tmp[1], tests[x].pt, 16)) {
	#if 0
	printf("\n\nFailed test %d\n", x);
	if (memcmp(tmp[0], tests[x].ct, 16)) {
	printf("Ciphertext: ");
	for (y = 0; y < 16; y++) printf("%02x ", tmp[0][y]);
	printf("\nExpected : ");
	for (y = 0; y < 16; y++) printf("%02x ", tests[x].ct[y]);
	printf("\n");
	}
	if (memcmp(tmp[1], tests[x].pt, 16)) {
	printf("Plaintext: ");
	for (y = 0; y < 16; y++) printf("%02x ", tmp[0][y]);
	printf("\nExpected : ");
	for (y = 0; y < 16; y++) printf("%02x ", tests[x].pt[y]);
	printf("\n");
	}
	#endif
	return CRYPT_FAIL_TESTVECTOR;
	}

	/* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
	for (y = 0; y < 16; y++) tmp[0][y] = 0;
	for (y = 0; y < 1000; y++) rc6_ecb_encrypt(tmp[0], tmp[0], &key);
	for (y = 0; y < 1000; y++) rc6_ecb_decrypt(tmp[0], tmp[0], &key);
	for (y = 0; y < 16; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
	}
	return CRYPT_OK;
	#endif
	}

	int rc6_keysize(int *desired_keysize)
	{
	_ARGCHK(desired_keysize != NULL);
	if (*desired_keysize < 8) {
	return CRYPT_INVALID_KEYSIZE;
	} else if (*desired_keysize > 128) {
	*desired_keysize = 128;
	}
	return CRYPT_OK;
	}

	#endif /RC6/