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Diffstat (limited to 'libtomcrypt/src/ciphers/xtea.c')
| -rw-r--r-- | libtomcrypt/src/ciphers/xtea.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/libtomcrypt/src/ciphers/xtea.c b/libtomcrypt/src/ciphers/xtea.c new file mode 100644 index 0000000..ac73400 --- /dev/null +++ b/libtomcrypt/src/ciphers/xtea.c @@ -0,0 +1,211 @@ +/* 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@gmail.com, http://libtomcrypt.com + */ + +/** + @file xtea.c + Implementation of XTEA, Tom St Denis +*/ +#include "tomcrypt.h" + +#ifdef XTEA + +const struct ltc_cipher_descriptor xtea_desc = +{ + "xtea", + 1, + 16, 16, 8, 32, + &xtea_setup, + &xtea_ecb_encrypt, + &xtea_ecb_decrypt, + &xtea_test, + &xtea_done, + &xtea_keysize, + NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL +}; + +int xtea_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) +{ + unsigned long x, sum, K[4]; + + LTC_ARGCHK(key != NULL); + LTC_ARGCHK(skey != NULL); + + /* check arguments */ + if (keylen != 16) { + return CRYPT_INVALID_KEYSIZE; + } + + if (num_rounds != 0 && num_rounds != 32) { + return CRYPT_INVALID_ROUNDS; + } + + /* load key */ + LOAD32L(K[0], key+0); + LOAD32L(K[1], key+4); + LOAD32L(K[2], key+8); + LOAD32L(K[3], key+12); + + for (x = sum = 0; x < 32; x++) { + skey->xtea.A[x] = (sum + K[sum&3]) & 0xFFFFFFFFUL; + sum = (sum + 0x9E3779B9UL) & 0xFFFFFFFFUL; + skey->xtea.B[x] = (sum + K[(sum>>11)&3]) & 0xFFFFFFFFUL; + } + +#ifdef LTC_CLEAN_STACK + zeromem(&K, sizeof(K)); +#endif + + return CRYPT_OK; +} + +/** + Encrypts a block of text with XTEA + @param pt The input plaintext (8 bytes) + @param ct The output ciphertext (8 bytes) + @param skey The key as scheduled + @return CRYPT_OK if successful +*/ +int xtea_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey) +{ + unsigned long y, z; + int r; + + LTC_ARGCHK(pt != NULL); + LTC_ARGCHK(ct != NULL); + LTC_ARGCHK(skey != NULL); + + LOAD32L(y, &pt[0]); + LOAD32L(z, &pt[4]); + for (r = 0; r < 32; r += 4) { + y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL; + z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL; + + y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+1])) & 0xFFFFFFFFUL; + z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+1])) & 0xFFFFFFFFUL; + + y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+2])) & 0xFFFFFFFFUL; + z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+2])) & 0xFFFFFFFFUL; + + y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+3])) & 0xFFFFFFFFUL; + z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+3])) & 0xFFFFFFFFUL; + } + STORE32L(y, &ct[0]); + STORE32L(z, &ct[4]); + return CRYPT_OK; +} + +/** + Decrypts a block of text with XTEA + @param ct The input ciphertext (8 bytes) + @param pt The output plaintext (8 bytes) + @param skey The key as scheduled + @return CRYPT_OK if successful +*/ +int xtea_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey) +{ + unsigned long y, z; + int r; + + LTC_ARGCHK(pt != NULL); + LTC_ARGCHK(ct != NULL); + LTC_ARGCHK(skey != NULL); + + LOAD32L(y, &ct[0]); + LOAD32L(z, &ct[4]); + for (r = 31; r >= 0; r -= 4) { + z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL; + y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL; + + z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-1])) & 0xFFFFFFFFUL; + y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-1])) & 0xFFFFFFFFUL; + + z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-2])) & 0xFFFFFFFFUL; + y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-2])) & 0xFFFFFFFFUL; + + z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-3])) & 0xFFFFFFFFUL; + y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-3])) & 0xFFFFFFFFUL; + } + STORE32L(y, &pt[0]); + STORE32L(z, &pt[4]); + return CRYPT_OK; +} + +/** + Performs a self-test of the XTEA block cipher + @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled +*/ +int xtea_test(void) +{ + #ifndef LTC_TEST + return CRYPT_NOP; + #else + static const unsigned char key[16] = + { 0x78, 0x56, 0x34, 0x12, 0xf0, 0xcd, 0xcb, 0x9a, + 0x48, 0x37, 0x26, 0x15, 0xc0, 0xbf, 0xae, 0x9d }; + static const unsigned char pt[8] = + { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 }; + static const unsigned char ct[8] = + { 0x75, 0xd7, 0xc5, 0xbf, 0xcf, 0x58, 0xc9, 0x3f }; + unsigned char tmp[2][8]; + symmetric_key skey; + int err, y; + + if ((err = xtea_setup(key, 16, 0, &skey)) != CRYPT_OK) { + return err; + } + xtea_ecb_encrypt(pt, tmp[0], &skey); + xtea_ecb_decrypt(tmp[0], tmp[1], &skey); + + if (XMEMCMP(tmp[0], ct, 8) != 0 || XMEMCMP(tmp[1], pt, 8) != 0) { + 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 < 8; y++) tmp[0][y] = 0; + for (y = 0; y < 1000; y++) xtea_ecb_encrypt(tmp[0], tmp[0], &skey); + for (y = 0; y < 1000; y++) xtea_ecb_decrypt(tmp[0], tmp[0], &skey); + for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR; + + return CRYPT_OK; + #endif +} + +/** Terminate the context + @param skey The scheduled key +*/ +void xtea_done(symmetric_key *skey) +{ +} + +/** + Gets suitable key size + @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable. + @return CRYPT_OK if the input key size is acceptable. +*/ +int xtea_keysize(int *keysize) +{ + LTC_ARGCHK(keysize != NULL); + if (*keysize < 16) { + return CRYPT_INVALID_KEYSIZE; + } + *keysize = 16; + return CRYPT_OK; +} + + +#endif + + + + +/* $Source: /cvs/libtom/libtomcrypt/src/ciphers/xtea.c,v $ */ +/* $Revision: 1.12 $ */ +/* $Date: 2006/11/08 23:01:06 $ */ |