/* * A 32-bit implementation of the TEA algorithm * Copyright (c) 2015 Vesselin Bontchev * * Loosely based on the implementation of David Wheeler and Roger Needham, * https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm#Reference_code * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "avutil.h" #include "common.h" #include "intreadwrite.h" #include "tea.h" typedef struct AVTEA { uint32_t key[16]; int rounds; } AVTEA; struct AVTEA *av_tea_alloc(void) { return av_mallocz(sizeof(struct AVTEA)); } const int av_tea_size = sizeof(AVTEA); void av_tea_init(AVTEA *ctx, const uint8_t key[16], int rounds) { int i; for (i = 0; i < 4; i++) ctx->key[i] = AV_RB32(key + (i << 2)); ctx->rounds = rounds; } static void tea_crypt_ecb(AVTEA *ctx, uint8_t *dst, const uint8_t *src, int decrypt, uint8_t *iv) { uint32_t v0, v1; int rounds = ctx->rounds; uint32_t k0, k1, k2, k3; k0 = ctx->key[0]; k1 = ctx->key[1]; k2 = ctx->key[2]; k3 = ctx->key[3]; v0 = AV_RB32(src); v1 = AV_RB32(src + 4); if (decrypt) { int i; uint32_t delta = 0x9E3779B9U, sum = delta * (rounds / 2); for (i = 0; i < rounds / 2; i++) { v1 -= ((v0 << 4) + k2) ^ (v0 + sum) ^ ((v0 >> 5) + k3); v0 -= ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1); sum -= delta; } if (iv) { v0 ^= AV_RB32(iv); v1 ^= AV_RB32(iv + 4); memcpy(iv, src, 8); } } else { int i; uint32_t sum = 0, delta = 0x9E3779B9U; for (i = 0; i < rounds / 2; i++) { sum += delta; v0 += ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1); v1 += ((v0 << 4) + k2) ^ (v0 + sum) ^ ((v0 >> 5) + k3); } } AV_WB32(dst, v0); AV_WB32(dst + 4, v1); } void av_tea_crypt(AVTEA *ctx, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt) { int i; if (decrypt) { while (count--) { tea_crypt_ecb(ctx, dst, src, decrypt, iv); src += 8; dst += 8; } } else { while (count--) { if (iv) { for (i = 0; i < 8; i++) dst[i] = src[i] ^ iv[i]; tea_crypt_ecb(ctx, dst, dst, decrypt, NULL); memcpy(iv, dst, 8); } else { tea_crypt_ecb(ctx, dst, src, decrypt, NULL); } src += 8; dst += 8; } } } #ifdef TEST #include <stdio.h> #define TEA_NUM_TESTS 4 // https://github.com/logandrews/TeaCrypt/blob/master/tea/tea_test.go static const uint8_t tea_test_key[TEA_NUM_TESTS][16] = { { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF }, { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF } }; static const uint8_t tea_test_pt[TEA_NUM_TESTS][8] = { { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 }, { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 }, { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF } }; static const uint8_t tea_test_ct[TEA_NUM_TESTS][8] = { { 0x41, 0xEA, 0x3A, 0x0A, 0x94, 0xBA, 0xA9, 0x40 }, { 0x6A, 0x2F, 0x9C, 0xF3, 0xFC, 0xCF, 0x3C, 0x55 }, { 0xDE, 0xB1, 0xC0, 0xA2, 0x7E, 0x74, 0x5D, 0xB3 }, { 0x12, 0x6C, 0x6B, 0x92, 0xC0, 0x65, 0x3A, 0x3E } }; static void test_tea(AVTEA *ctx, uint8_t *dst, const uint8_t *src, const uint8_t *ref, int len, uint8_t *iv, int dir, const char *test) { av_tea_crypt(ctx, dst, src, len, iv, dir); if (memcmp(dst, ref, 8*len)) { int i; printf("%s failed\ngot ", test); for (i = 0; i < 8*len; i++) printf("%02x ", dst[i]); printf("\nexpected "); for (i = 0; i < 8*len; i++) printf("%02x ", ref[i]); printf("\n"); exit(1); } } int main(void) { AVTEA *ctx; uint8_t buf[8], iv[8]; int i; static const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld"; uint8_t ct[32]; uint8_t pl[32]; ctx = av_tea_alloc(); if (!ctx) return 1; for (i = 0; i < TEA_NUM_TESTS; i++) { av_tea_init(ctx, tea_test_key[i], 64); test_tea(ctx, buf, tea_test_pt[i], tea_test_ct[i], 1, NULL, 0, "encryption"); test_tea(ctx, buf, tea_test_ct[i], tea_test_pt[i], 1, NULL, 1, "decryption"); /* encrypt */ memcpy(iv, "HALLO123", 8); av_tea_crypt(ctx, ct, src, 4, iv, 0); /* decrypt into pl */ memcpy(iv, "HALLO123", 8); test_tea(ctx, pl, ct, src, 4, iv, 1, "CBC decryption"); memcpy(iv, "HALLO123", 8); test_tea(ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption"); } printf("Test encryption/decryption success.\n"); av_free(ctx); return 0; } #endif