153 lines
3.8 KiB
C
153 lines
3.8 KiB
C
#include "mycrypt.h"
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#ifdef XTEA
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const struct _cipher_descriptor xtea_desc =
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{
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"xtea",
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1,
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16, 16, 8, 32,
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&xtea_setup,
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&xtea_ecb_encrypt,
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&xtea_ecb_decrypt,
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&xtea_test,
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&xtea_keysize
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};
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int xtea_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
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{
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unsigned long x, sum, K[4];
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_ARGCHK(key != NULL);
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_ARGCHK(skey != NULL);
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/* check arguments */
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if (keylen != 16) {
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return CRYPT_INVALID_KEYSIZE;
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}
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if (num_rounds != 0 && num_rounds != 32) {
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return CRYPT_INVALID_ROUNDS;
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}
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/* load key */
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LOAD32L(K[0], key+0);
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LOAD32L(K[1], key+4);
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LOAD32L(K[2], key+8);
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LOAD32L(K[3], key+12);
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for (x = sum = 0; x < 32; x++) {
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skey->xtea.A[x] = (sum + K[sum&3]) & 0xFFFFFFFFUL;
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sum = (sum + 0x9E3779B9UL) & 0xFFFFFFFFUL;
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skey->xtea.B[x] = (sum + K[(sum>>11)&3]) & 0xFFFFFFFFUL;
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}
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#ifdef CLEAN_STACK
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zeromem(&K, sizeof(K));
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#endif
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return CRYPT_OK;
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}
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void xtea_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
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{
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unsigned long y, z;
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int r;
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_ARGCHK(pt != NULL);
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_ARGCHK(ct != NULL);
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_ARGCHK(key != NULL);
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LOAD32L(y, &pt[0]);
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LOAD32L(z, &pt[4]);
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for (r = 0; r < 32; r += 4) {
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y = (y + ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r])) & 0xFFFFFFFFUL;
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z = (z + ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r])) & 0xFFFFFFFFUL;
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y = (y + ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r+1])) & 0xFFFFFFFFUL;
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z = (z + ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r+1])) & 0xFFFFFFFFUL;
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y = (y + ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r+2])) & 0xFFFFFFFFUL;
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z = (z + ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r+2])) & 0xFFFFFFFFUL;
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y = (y + ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r+3])) & 0xFFFFFFFFUL;
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z = (z + ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r+3])) & 0xFFFFFFFFUL;
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}
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STORE32L(y, &ct[0]);
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STORE32L(z, &ct[4]);
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}
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void xtea_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
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{
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unsigned long y, z;
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int r;
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_ARGCHK(pt != NULL);
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_ARGCHK(ct != NULL);
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_ARGCHK(key != NULL);
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LOAD32L(y, &ct[0]);
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LOAD32L(z, &ct[4]);
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for (r = 31; r >= 0; r -= 4) {
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z = (z - ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r])) & 0xFFFFFFFFUL;
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y = (y - ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r])) & 0xFFFFFFFFUL;
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z = (z - ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r-1])) & 0xFFFFFFFFUL;
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y = (y - ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r-1])) & 0xFFFFFFFFUL;
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z = (z - ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r-2])) & 0xFFFFFFFFUL;
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y = (y - ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r-2])) & 0xFFFFFFFFUL;
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z = (z - ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r-3])) & 0xFFFFFFFFUL;
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y = (y - ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r-3])) & 0xFFFFFFFFUL;
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}
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STORE32L(y, &pt[0]);
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STORE32L(z, &pt[4]);
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}
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int xtea_test(void)
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{
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#ifndef LTC_TEST
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return CRYPT_NOP;
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#else
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static const unsigned char key[16] =
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{ 0x78, 0x56, 0x34, 0x12, 0xf0, 0xcd, 0xcb, 0x9a,
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0x48, 0x37, 0x26, 0x15, 0xc0, 0xbf, 0xae, 0x9d };
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static const unsigned char pt[8] =
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{ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };
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static const unsigned char ct[8] =
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{ 0x75, 0xd7, 0xc5, 0xbf, 0xcf, 0x58, 0xc9, 0x3f };
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unsigned char tmp[2][8];
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symmetric_key skey;
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int err;
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if ((err = xtea_setup(key, 16, 0, &skey)) != CRYPT_OK) {
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return err;
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}
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xtea_ecb_encrypt(pt, tmp[0], &skey);
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xtea_ecb_decrypt(tmp[0], tmp[1], &skey);
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if (memcmp(tmp[0], ct, 8) != 0 || memcmp(tmp[1], pt, 8) != 0) {
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return CRYPT_FAIL_TESTVECTOR;
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}
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return CRYPT_OK;
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#endif
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}
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int xtea_keysize(int *desired_keysize)
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{
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_ARGCHK(desired_keysize != NULL);
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if (*desired_keysize < 16) {
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return CRYPT_INVALID_KEYSIZE;
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}
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*desired_keysize = 16;
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return CRYPT_OK;
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}
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#endif
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