/** Test the OCB protocol @return CRYPT_OK if successful */ int ocb3_test(void) { #ifndef LTC_TEST return CRYPT_NOP; #else /* test vectors from: http://tools.ietf.org/html/draft-krovetz-ocb-03 */ unsigned char key[16] = { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F }; unsigned char nonce[12] = { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B }; const struct { int ptlen; int aadlen; unsigned char pt[64], aad[64], ct[64], tag[16]; } tests[] = { { /* index:0 */ 0, /* PLAINTEXT length */ 0, /* AAD length */ { 0 }, /* PLAINTEXT */ { 0 }, /* AAD */ { 0 }, /* CIPHERTEXT */ { 0x19,0x7b,0x9c,0x3c,0x44,0x1d,0x3c,0x83,0xea,0xfb,0x2b,0xef,0x63,0x3b,0x91,0x82 }, /* TAG */ }, { /* index:1 */ 8, /* PLAINTEXT length */ 8, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07 }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07 }, /* AAD */ { 0x92,0xb6,0x57,0x13,0x0a,0x74,0xb8,0x5a }, /* CIPHERTEXT */ { 0x16,0xdc,0x76,0xa4,0x6d,0x47,0xe1,0xea,0xd5,0x37,0x20,0x9e,0x8a,0x96,0xd1,0x4e }, /* TAG */ }, { /* index:2 */ 0, /* PLAINTEXT length */ 8, /* AAD length */ { 0 }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07 }, /* AAD */ { 0 }, /* CIPHERTEXT */ { 0x98,0xb9,0x15,0x52,0xc8,0xc0,0x09,0x18,0x50,0x44,0xe3,0x0a,0x6e,0xb2,0xfe,0x21 }, /* TAG */ }, { /* index:3 */ 8, /* PLAINTEXT length */ 0, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07 }, /* PLAINTEXT */ { 0 }, /* AAD */ { 0x92,0xb6,0x57,0x13,0x0a,0x74,0xb8,0x5a }, /* CIPHERTEXT */ { 0x97,0x1e,0xff,0xca,0xe1,0x9a,0xd4,0x71,0x6f,0x88,0xe8,0x7b,0x87,0x1f,0xbe,0xed }, /* TAG */ }, { /* index:4 */ 16, /* PLAINTEXT length */ 16, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f }, /* AAD */ { 0xbe,0xa5,0xe8,0x79,0x8d,0xbe,0x71,0x10,0x03,0x1c,0x14,0x4d,0xa0,0xb2,0x61,0x22 }, /* CIPHERTEXT */ { 0x77,0x6c,0x99,0x24,0xd6,0x72,0x3a,0x1f,0xc4,0x52,0x45,0x32,0xac,0x3e,0x5b,0xeb }, /* TAG */ }, { /* index:5 */ 0, /* PLAINTEXT length */ 16, /* AAD length */ { 0 }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f }, /* AAD */ { 0 }, /* CIPHERTEXT */ { 0x7d,0xdb,0x8e,0x6c,0xea,0x68,0x14,0x86,0x62,0x12,0x50,0x96,0x19,0xb1,0x9c,0xc6 }, /* TAG */ }, { /* index:6 */ 16, /* PLAINTEXT length */ 0, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f }, /* PLAINTEXT */ { 0 }, /* AAD */ { 0xbe,0xa5,0xe8,0x79,0x8d,0xbe,0x71,0x10,0x03,0x1c,0x14,0x4d,0xa0,0xb2,0x61,0x22 }, /* CIPHERTEXT */ { 0x13,0xcc,0x8b,0x74,0x78,0x07,0x12,0x1a,0x4c,0xbb,0x3e,0x4b,0xd6,0xb4,0x56,0xaf }, /* TAG */ }, { /* index:7 */ 24, /* PLAINTEXT length */ 24, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17 }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17 }, /* AAD */ { 0xbe,0xa5,0xe8,0x79,0x8d,0xbe,0x71,0x10,0x03,0x1c,0x14,0x4d,0xa0,0xb2,0x61,0x22,0xfc,0xfc,0xee,0x7a,0x2a,0x8d,0x4d,0x48 }, /* CIPHERTEXT */ { 0x5f,0xa9,0x4f,0xc3,0xf3,0x88,0x20,0xf1,0xdc,0x3f,0x3d,0x1f,0xd4,0xe5,0x5e,0x1c }, /* TAG */ }, { /* index:8 */ 0, /* PLAINTEXT length */ 24, /* AAD length */ { 0 }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17 }, /* AAD */ { 0 }, /* CIPHERTEXT */ { 0x28,0x20,0x26,0xda,0x30,0x68,0xbc,0x9f,0xa1,0x18,0x68,0x1d,0x55,0x9f,0x10,0xf6 }, /* TAG */ }, { /* index:9 */ 24, /* PLAINTEXT length */ 0, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17 }, /* PLAINTEXT */ { 0 }, /* AAD */ { 0xbe,0xa5,0xe8,0x79,0x8d,0xbe,0x71,0x10,0x03,0x1c,0x14,0x4d,0xa0,0xb2,0x61,0x22,0xfc,0xfc,0xee,0x7a,0x2a,0x8d,0x4d,0x48 }, /* CIPHERTEXT */ { 0x6e,0xf2,0xf5,0x25,0x87,0xfd,0xa0,0xed,0x97,0xdc,0x7e,0xed,0xe2,0x41,0xdf,0x68 }, /* TAG */ }, { /* index:10 */ 32, /* PLAINTEXT length */ 32, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f }, /* AAD */ { 0xbe,0xa5,0xe8,0x79,0x8d,0xbe,0x71,0x10,0x03,0x1c,0x14,0x4d,0xa0,0xb2,0x61,0x22,0xce,0xaa,0xb9,0xb0,0x5d,0xf7,0x71,0xa6,0x57,0x14,0x9d,0x53,0x77,0x34,0x63,0xcb }, /* CIPHERTEXT */ { 0xb2,0xa0,0x40,0xdd,0x3b,0xd5,0x16,0x43,0x72,0xd7,0x6d,0x7b,0xb6,0x82,0x42,0x40 }, /* TAG */ }, { /* index:11 */ 0, /* PLAINTEXT length */ 32, /* AAD length */ { 0 }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f }, /* AAD */ { 0 }, /* CIPHERTEXT */ { 0xe1,0xe0,0x72,0x63,0x3b,0xad,0xe5,0x1a,0x60,0xe8,0x59,0x51,0xd9,0xc4,0x2a,0x1b }, /* TAG */ }, { /* index:12 */ 32, /* PLAINTEXT length */ 0, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f }, /* PLAINTEXT */ { 0 }, /* AAD */ { 0xbe,0xa5,0xe8,0x79,0x8d,0xbe,0x71,0x10,0x03,0x1c,0x14,0x4d,0xa0,0xb2,0x61,0x22,0xce,0xaa,0xb9,0xb0,0x5d,0xf7,0x71,0xa6,0x57,0x14,0x9d,0x53,0x77,0x34,0x63,0xcb }, /* CIPHERTEXT */ { 0x4a,0x3b,0xae,0x82,0x44,0x65,0xcf,0xda,0xf8,0xc4,0x1f,0xc5,0x0c,0x7d,0xf9,0xd9 }, /* TAG */ }, { /* index:13 */ 40, /* PLAINTEXT length */ 40, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27 }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27 }, /* AAD */ { 0xbe,0xa5,0xe8,0x79,0x8d,0xbe,0x71,0x10,0x03,0x1c,0x14,0x4d,0xa0,0xb2,0x61,0x22,0xce,0xaa,0xb9,0xb0,0x5d,0xf7,0x71,0xa6,0x57,0x14,0x9d,0x53,0x77,0x34,0x63,0xcb,0x68,0xc6,0x57,0x78,0xb0,0x58,0xa6,0x35 }, /* CIPHERTEXT */ { 0x65,0x9c,0x62,0x32,0x11,0xde,0xea,0x0d,0xe3,0x0d,0x2c,0x38,0x18,0x79,0xf4,0xc8 }, /* TAG */ }, { /* index:14 */ 0, /* PLAINTEXT length */ 40, /* AAD length */ { 0 }, /* PLAINTEXT */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27 }, /* AAD */ { 0 }, /* CIPHERTEXT */ { 0x7a,0xeb,0x7a,0x69,0xa1,0x68,0x7d,0xd0,0x82,0xca,0x27,0xb0,0xd9,0xa3,0x70,0x96 }, /* TAG */ }, { /* index:15 */ 40, /* PLAINTEXT length */ 0, /* AAD length */ { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27 }, /* PLAINTEXT */ { 0 }, /* AAD */ { 0xbe,0xa5,0xe8,0x79,0x8d,0xbe,0x71,0x10,0x03,0x1c,0x14,0x4d,0xa0,0xb2,0x61,0x22,0xce,0xaa,0xb9,0xb0,0x5d,0xf7,0x71,0xa6,0x57,0x14,0x9d,0x53,0x77,0x34,0x63,0xcb,0x68,0xc6,0x57,0x78,0xb0,0x58,0xa6,0x35 }, /* CIPHERTEXT */ { 0x06,0x0c,0x84,0x67,0xf4,0xab,0xab,0x5e,0x8b,0x3c,0x20,0x67,0xa2,0xe1,0x15,0xdc }, /* TAG */ }, }; /* As of RFC 7253 - 'Appendix A. Sample Results' * The next tuple shows a result with a tag length of 96 bits and a different key. K: 0F0E0D0C0B0A09080706050403020100 N: BBAA9988776655443322110D A: 000102030405060708090A0B0C0D0E0F1011121314151617 18191A1B1C1D1E1F2021222324252627 P: 000102030405060708090A0B0C0D0E0F1011121314151617 18191A1B1C1D1E1F2021222324252627 C: 1792A4E31E0755FB03E31B22116E6C2DDF9EFD6E33D536F1 A0124B0A55BAE884ED93481529C76B6AD0C515F4D1CDD4FD AC4F02AA The C has been split up in C and T (tag) */ const unsigned char K[] = { 0x0F,0x0E,0x0D,0x0C,0x0B,0x0A,0x09,0x08, 0x07,0x06,0x05,0x04,0x03,0x02,0x01,0x00 }; const unsigned char N[] = { 0xBB,0xAA,0x99,0x88,0x77,0x66,0x55,0x44, 0x33,0x22,0x11,0x0D }; const unsigned char A[] = { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07, 0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F, 0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17, 0x18,0x19,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F, 0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27 }; const unsigned char P[] = { 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07, 0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F, 0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17, 0x18,0x19,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F, 0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27 }; const unsigned char C[] = { 0x17,0x92,0xA4,0xE3,0x1E,0x07,0x55,0xFB, 0x03,0xE3,0x1B,0x22,0x11,0x6E,0x6C,0x2D, 0xDF,0x9E,0xFD,0x6E,0x33,0xD5,0x36,0xF1, 0xA0,0x12,0x4B,0x0A,0x55,0xBA,0xE8,0x84, 0xED,0x93,0x48,0x15,0x29,0xC7,0x6B,0x6A }; const unsigned char T[] = { 0xD0,0xC5,0x15,0xF4,0xD1,0xCD,0xD4,0xFD, 0xAC,0x4F,0x02,0xAA }; int err, x, idx, res; unsigned long len; unsigned char outct[MAXBLOCKSIZE] = { 0 }; unsigned char outtag[MAXBLOCKSIZE] = { 0 }; ocb3_state ocb; /* AES can be under rijndael or aes... try to find it */ if ((idx = find_cipher("aes")) == -1) { if ((idx = find_cipher("rijndael")) == -1) { return CRYPT_NOP; } } for (x = 0; x < (int)(sizeof(tests)/sizeof(tests[0])); x++) { len = 16; /* must be the same as the required taglen */ if ((err = ocb3_encrypt_authenticate_memory(idx, key, sizeof(key), nonce, sizeof(nonce), tests[x].aadlen != 0 ? tests[x].aad : NULL, tests[x].aadlen, tests[x].ptlen != 0 ? tests[x].pt : NULL, tests[x].ptlen, tests[x].ptlen != 0 ? outct : NULL, outtag, &len)) != CRYPT_OK) { return err; } if (compare_testvector(outtag, len, tests[x].tag, sizeof(tests[x].tag), "OCB3 Tag", x) || compare_testvector(outct, tests[x].ptlen, tests[x].ct, tests[x].ptlen, "OCB3 CT", x)) { return CRYPT_FAIL_TESTVECTOR; } if ((err = ocb3_decrypt_verify_memory(idx, key, sizeof(key), nonce, sizeof(nonce), tests[x].aadlen != 0 ? tests[x].aad : NULL, tests[x].aadlen, tests[x].ptlen != 0 ? outct : NULL, tests[x].ptlen, tests[x].ptlen != 0 ? outct : NULL, tests[x].tag, len, &res)) != CRYPT_OK) { return err; } if ((res != 1) || compare_testvector(outct, tests[x].ptlen, tests[x].pt, tests[x].ptlen, "OCB3", x)) { #ifdef LTC_TEST_DBG printf("\n\nOCB3: Failure-decrypt - res = %d\n", res); #endif return CRYPT_FAIL_TESTVECTOR; } } /* RFC 7253 - test vector with a tag length of 96 bits - part 1 */ x = 99; len = 12; if ((err = ocb3_encrypt_authenticate_memory(idx, K, sizeof(K), N, sizeof(N), A, sizeof(A), P, sizeof(P), outct, outtag, &len)) != CRYPT_OK) { return err; } if (compare_testvector(outtag, len, T, sizeof(T), "OCB3 Tag", x) || compare_testvector(outct, sizeof(P), C, sizeof(C), "OCB3 CT", x)) { return CRYPT_FAIL_TESTVECTOR; } if ((err = ocb3_decrypt_verify_memory(idx, K, sizeof(K), N, sizeof(N), A, sizeof(A), C, sizeof(C), outct, T, sizeof(T), &res)) != CRYPT_OK) { return err; } if ((res != 1) || compare_testvector(outct, sizeof(C), P, sizeof(P), "OCB3", x)) { #ifdef LTC_TEST_DBG printf("\n\nOCB3: Failure-decrypt - res = %d\n", res); #endif return CRYPT_FAIL_TESTVECTOR; } /* RFC 7253 - test vector with a tag length of 96 bits - part 2 */ x = 100; if ((err = ocb3_init(&ocb, idx, K, sizeof(K), N, sizeof(N), 12)) != CRYPT_OK) return err; if ((err = ocb3_add_aad(&ocb, A, sizeof(A))) != CRYPT_OK) return err; if ((err = ocb3_encrypt(&ocb, P, 32, outct)) != CRYPT_OK) return err; if ((err = ocb3_encrypt_last(&ocb, P+32, sizeof(P)-32, outct+32)) != CRYPT_OK) return err; len = sizeof(outtag); /* intentionally more than 12 */ if ((err = ocb3_done(&ocb, outtag, &len)) != CRYPT_OK) return err; if (compare_testvector(outct, sizeof(P), C, sizeof(C), "OCB3 CT", x)) return CRYPT_FAIL_TESTVECTOR; if (compare_testvector(outtag, len, T, sizeof(T), "OCB3 Tag.enc", x)) return CRYPT_FAIL_TESTVECTOR; if ((err = ocb3_init(&ocb, idx, K, sizeof(K), N, sizeof(N), 12)) != CRYPT_OK) return err; if ((err = ocb3_add_aad(&ocb, A, sizeof(A))) != CRYPT_OK) return err; if ((err = ocb3_decrypt(&ocb, C, 32, outct)) != CRYPT_OK) return err; if ((err = ocb3_decrypt_last(&ocb, C+32, sizeof(C)-32, outct+32)) != CRYPT_OK) return err; len = sizeof(outtag); /* intentionally more than 12 */ if ((err = ocb3_done(&ocb, outtag, &len)) != CRYPT_OK) return err; if (compare_testvector(outct, sizeof(C), P, sizeof(P), "OCB3 PT", x)) return CRYPT_FAIL_TESTVECTOR; if (compare_testvector(outtag, len, T, sizeof(T), "OCB3 Tag.dec", x)) return CRYPT_FAIL_TESTVECTOR; return CRYPT_OK; #endif /* LTC_TEST */ }
/** Finish an OCB (decryption) stream @param ocb The OCB state @param ct The remaining ciphertext @param ctlen The length of the ciphertext (octets) @param pt [out] The output buffer @return CRYPT_OK if successful */ int ocb3_decrypt_last(ocb3_state *ocb, const unsigned char *ct, unsigned long ctlen, unsigned char *pt) { unsigned char iOffset_star[MAXBLOCKSIZE]; unsigned char iPad[MAXBLOCKSIZE]; int err, x, full_blocks, full_blocks_len, last_block_len; LTC_ARGCHK(ocb != NULL); LTC_ARGCHK(ct != NULL); if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) { goto LBL_ERR; } full_blocks = ctlen/ocb->block_len; full_blocks_len = full_blocks * ocb->block_len; last_block_len = ctlen - full_blocks_len; /* process full blocks first */ if (full_blocks>0) { if ((err = ocb3_decrypt(ocb, ct, full_blocks_len, pt)) != CRYPT_OK) { goto LBL_ERR; } } if (last_block_len>0) { /* Offset_* = Offset_m xor L_* */ ocb3_int_xor_blocks(iOffset_star, ocb->Offset_current, ocb->L_star, ocb->block_len); /* Pad = ENCIPHER(K, Offset_*) */ if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(iOffset_star, iPad, &ocb->key)) != CRYPT_OK) { goto LBL_ERR; } /* P_* = C_* xor Pad[1..bitlen(C_*)] */ ocb3_int_xor_blocks(pt+full_blocks_len, (unsigned char *)ct+full_blocks_len, iPad, last_block_len); /* Checksum_* = Checksum_m xor (P_* || 1 || zeros(127-bitlen(P_*))) */ ocb3_int_xor_blocks(ocb->checksum, ocb->checksum, pt+full_blocks_len, last_block_len); for(x=last_block_len; x<ocb->block_len; x++) { if (x == last_block_len) ocb->checksum[x] ^= 0x80; else ocb->checksum[x] ^= 0x00; } /* Tag = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) xor HASH(K,A) */ /* at this point we calculate only: Tag_part = ENCIPHER(K, Checksum_* xor Offset_* xor L_$) */ for(x=0; x<ocb->block_len; x++) { ocb->tag_part[x] = (ocb->checksum[x] ^ iOffset_star[x]) ^ ocb->L_dollar[x]; } if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(ocb->tag_part, ocb->tag_part, &ocb->key)) != CRYPT_OK) { goto LBL_ERR; } } else { /* Tag = ENCIPHER(K, Checksum_m xor Offset_m xor L_$) xor HASH(K,A) */ /* at this point we calculate only: Tag_part = ENCIPHER(K, Checksum_m xor Offset_m xor L_$) */ for(x=0; x<ocb->block_len; x++) { ocb->tag_part[x] = (ocb->checksum[x] ^ ocb->Offset_current[x]) ^ ocb->L_dollar[x]; } if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(ocb->tag_part, ocb->tag_part, &ocb->key)) != CRYPT_OK) { goto LBL_ERR; } } err = CRYPT_OK; LBL_ERR: #ifdef LTC_CLEAN_STACK zeromem(iOffset_star, MAXBLOCKSIZE); zeromem(iPad, MAXBLOCKSIZE); #endif return err; }