diff options
Diffstat (limited to 'library/chachapoly.c')
| -rw-r--r-- | library/chachapoly.c | 478 |
1 files changed, 478 insertions, 0 deletions
diff --git a/library/chachapoly.c b/library/chachapoly.c new file mode 100644 index 00000000000..a1314eab6df --- /dev/null +++ b/library/chachapoly.c @@ -0,0 +1,478 @@ +/** + * \file chachapoly.c + * + * \brief ChaCha20-Poly1305 AEAD construction based on RFC 7539. + * + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ +#include "common.h" + +#if defined(MBEDTLS_CHACHAPOLY_C) + +#include "mbedtls/chachapoly.h" +#include "mbedtls/platform_util.h" +#include "mbedtls/error.h" +#include "mbedtls/constant_time.h" + +#include <string.h> + +#include "mbedtls/platform.h" + +#if !defined(MBEDTLS_CHACHAPOLY_ALT) + +#define CHACHAPOLY_STATE_INIT (0) +#define CHACHAPOLY_STATE_AAD (1) +#define CHACHAPOLY_STATE_CIPHERTEXT (2) /* Encrypting or decrypting */ +#define CHACHAPOLY_STATE_FINISHED (3) + +/** + * \brief Adds nul bytes to pad the AAD for Poly1305. + * + * \param ctx The ChaCha20-Poly1305 context. + */ +static int chachapoly_pad_aad(mbedtls_chachapoly_context *ctx) +{ + uint32_t partial_block_len = (uint32_t) (ctx->aad_len % 16U); + unsigned char zeroes[15]; + + if (partial_block_len == 0U) { + return 0; + } + + memset(zeroes, 0, sizeof(zeroes)); + + return mbedtls_poly1305_update(&ctx->poly1305_ctx, + zeroes, + 16U - partial_block_len); +} + +/** + * \brief Adds nul bytes to pad the ciphertext for Poly1305. + * + * \param ctx The ChaCha20-Poly1305 context. + */ +static int chachapoly_pad_ciphertext(mbedtls_chachapoly_context *ctx) +{ + uint32_t partial_block_len = (uint32_t) (ctx->ciphertext_len % 16U); + unsigned char zeroes[15]; + + if (partial_block_len == 0U) { + return 0; + } + + memset(zeroes, 0, sizeof(zeroes)); + return mbedtls_poly1305_update(&ctx->poly1305_ctx, + zeroes, + 16U - partial_block_len); +} + +void mbedtls_chachapoly_init(mbedtls_chachapoly_context *ctx) +{ + mbedtls_chacha20_init(&ctx->chacha20_ctx); + mbedtls_poly1305_init(&ctx->poly1305_ctx); + ctx->aad_len = 0U; + ctx->ciphertext_len = 0U; + ctx->state = CHACHAPOLY_STATE_INIT; + ctx->mode = MBEDTLS_CHACHAPOLY_ENCRYPT; +} + +void mbedtls_chachapoly_free(mbedtls_chachapoly_context *ctx) +{ + if (ctx == NULL) { + return; + } + + mbedtls_chacha20_free(&ctx->chacha20_ctx); + mbedtls_poly1305_free(&ctx->poly1305_ctx); + ctx->aad_len = 0U; + ctx->ciphertext_len = 0U; + ctx->state = CHACHAPOLY_STATE_INIT; + ctx->mode = MBEDTLS_CHACHAPOLY_ENCRYPT; +} + +int mbedtls_chachapoly_setkey(mbedtls_chachapoly_context *ctx, + const unsigned char key[32]) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + ret = mbedtls_chacha20_setkey(&ctx->chacha20_ctx, key); + + return ret; +} + +int mbedtls_chachapoly_starts(mbedtls_chachapoly_context *ctx, + const unsigned char nonce[12], + mbedtls_chachapoly_mode_t mode) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char poly1305_key[64]; + + /* Set counter = 0, will be update to 1 when generating Poly1305 key */ + ret = mbedtls_chacha20_starts(&ctx->chacha20_ctx, nonce, 0U); + if (ret != 0) { + goto cleanup; + } + + /* Generate the Poly1305 key by getting the ChaCha20 keystream output with + * counter = 0. This is the same as encrypting a buffer of zeroes. + * Only the first 256-bits (32 bytes) of the key is used for Poly1305. + * The other 256 bits are discarded. + */ + memset(poly1305_key, 0, sizeof(poly1305_key)); + ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, sizeof(poly1305_key), + poly1305_key, poly1305_key); + if (ret != 0) { + goto cleanup; + } + + ret = mbedtls_poly1305_starts(&ctx->poly1305_ctx, poly1305_key); + + if (ret == 0) { + ctx->aad_len = 0U; + ctx->ciphertext_len = 0U; + ctx->state = CHACHAPOLY_STATE_AAD; + ctx->mode = mode; + } + +cleanup: + mbedtls_platform_zeroize(poly1305_key, 64U); + return ret; +} + +int mbedtls_chachapoly_update_aad(mbedtls_chachapoly_context *ctx, + const unsigned char *aad, + size_t aad_len) +{ + if (ctx->state != CHACHAPOLY_STATE_AAD) { + return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE; + } + + ctx->aad_len += aad_len; + + return mbedtls_poly1305_update(&ctx->poly1305_ctx, aad, aad_len); +} + +int mbedtls_chachapoly_update(mbedtls_chachapoly_context *ctx, + size_t len, + const unsigned char *input, + unsigned char *output) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + if ((ctx->state != CHACHAPOLY_STATE_AAD) && + (ctx->state != CHACHAPOLY_STATE_CIPHERTEXT)) { + return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE; + } + + if (ctx->state == CHACHAPOLY_STATE_AAD) { + ctx->state = CHACHAPOLY_STATE_CIPHERTEXT; + + ret = chachapoly_pad_aad(ctx); + if (ret != 0) { + return ret; + } + } + + ctx->ciphertext_len += len; + + if (ctx->mode == MBEDTLS_CHACHAPOLY_ENCRYPT) { + ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, len, input, output); + if (ret != 0) { + return ret; + } + + ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, output, len); + if (ret != 0) { + return ret; + } + } else { /* DECRYPT */ + ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, input, len); + if (ret != 0) { + return ret; + } + + ret = mbedtls_chacha20_update(&ctx->chacha20_ctx, len, input, output); + if (ret != 0) { + return ret; + } + } + + return 0; +} + +int mbedtls_chachapoly_finish(mbedtls_chachapoly_context *ctx, + unsigned char mac[16]) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char len_block[16]; + + if (ctx->state == CHACHAPOLY_STATE_INIT) { + return MBEDTLS_ERR_CHACHAPOLY_BAD_STATE; + } + + if (ctx->state == CHACHAPOLY_STATE_AAD) { + ret = chachapoly_pad_aad(ctx); + if (ret != 0) { + return ret; + } + } else if (ctx->state == CHACHAPOLY_STATE_CIPHERTEXT) { + ret = chachapoly_pad_ciphertext(ctx); + if (ret != 0) { + return ret; + } + } + + ctx->state = CHACHAPOLY_STATE_FINISHED; + + /* The lengths of the AAD and ciphertext are processed by + * Poly1305 as the final 128-bit block, encoded as little-endian integers. + */ + MBEDTLS_PUT_UINT64_LE(ctx->aad_len, len_block, 0); + MBEDTLS_PUT_UINT64_LE(ctx->ciphertext_len, len_block, 8); + + ret = mbedtls_poly1305_update(&ctx->poly1305_ctx, len_block, 16U); + if (ret != 0) { + return ret; + } + + ret = mbedtls_poly1305_finish(&ctx->poly1305_ctx, mac); + + return ret; +} + +static int chachapoly_crypt_and_tag(mbedtls_chachapoly_context *ctx, + mbedtls_chachapoly_mode_t mode, + size_t length, + const unsigned char nonce[12], + const unsigned char *aad, + size_t aad_len, + const unsigned char *input, + unsigned char *output, + unsigned char tag[16]) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + ret = mbedtls_chachapoly_starts(ctx, nonce, mode); + if (ret != 0) { + goto cleanup; + } + + ret = mbedtls_chachapoly_update_aad(ctx, aad, aad_len); + if (ret != 0) { + goto cleanup; + } + + ret = mbedtls_chachapoly_update(ctx, length, input, output); + if (ret != 0) { + goto cleanup; + } + + ret = mbedtls_chachapoly_finish(ctx, tag); + +cleanup: + return ret; +} + +int mbedtls_chachapoly_encrypt_and_tag(mbedtls_chachapoly_context *ctx, + size_t length, + const unsigned char nonce[12], + const unsigned char *aad, + size_t aad_len, + const unsigned char *input, + unsigned char *output, + unsigned char tag[16]) +{ + return chachapoly_crypt_and_tag(ctx, MBEDTLS_CHACHAPOLY_ENCRYPT, + length, nonce, aad, aad_len, + input, output, tag); +} + +int mbedtls_chachapoly_auth_decrypt(mbedtls_chachapoly_context *ctx, + size_t length, + const unsigned char nonce[12], + const unsigned char *aad, + size_t aad_len, + const unsigned char tag[16], + const unsigned char *input, + unsigned char *output) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char check_tag[16]; + int diff; + + if ((ret = chachapoly_crypt_and_tag(ctx, + MBEDTLS_CHACHAPOLY_DECRYPT, length, nonce, + aad, aad_len, input, output, check_tag)) != 0) { + return ret; + } + + /* Check tag in "constant-time" */ + diff = mbedtls_ct_memcmp(tag, check_tag, sizeof(check_tag)); + + if (diff != 0) { + mbedtls_platform_zeroize(output, length); + return MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED; + } + + return 0; +} + +#endif /* MBEDTLS_CHACHAPOLY_ALT */ + +#if defined(MBEDTLS_SELF_TEST) + +static const unsigned char test_key[1][32] = +{ + { + 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, + 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, + 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, + 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f + } +}; + +static const unsigned char test_nonce[1][12] = +{ + { + 0x07, 0x00, 0x00, 0x00, /* 32-bit common part */ + 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47 /* 64-bit IV */ + } +}; + +static const unsigned char test_aad[1][12] = +{ + { + 0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3, + 0xc4, 0xc5, 0xc6, 0xc7 + } +}; + +static const size_t test_aad_len[1] = +{ + 12U +}; + +static const unsigned char test_input[1][114] = +{ + { + 0x4c, 0x61, 0x64, 0x69, 0x65, 0x73, 0x20, 0x61, + 0x6e, 0x64, 0x20, 0x47, 0x65, 0x6e, 0x74, 0x6c, + 0x65, 0x6d, 0x65, 0x6e, 0x20, 0x6f, 0x66, 0x20, + 0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x61, 0x73, + 0x73, 0x20, 0x6f, 0x66, 0x20, 0x27, 0x39, 0x39, + 0x3a, 0x20, 0x49, 0x66, 0x20, 0x49, 0x20, 0x63, + 0x6f, 0x75, 0x6c, 0x64, 0x20, 0x6f, 0x66, 0x66, + 0x65, 0x72, 0x20, 0x79, 0x6f, 0x75, 0x20, 0x6f, + 0x6e, 0x6c, 0x79, 0x20, 0x6f, 0x6e, 0x65, 0x20, + 0x74, 0x69, 0x70, 0x20, 0x66, 0x6f, 0x72, 0x20, + 0x74, 0x68, 0x65, 0x20, 0x66, 0x75, 0x74, 0x75, + 0x72, 0x65, 0x2c, 0x20, 0x73, 0x75, 0x6e, 0x73, + 0x63, 0x72, 0x65, 0x65, 0x6e, 0x20, 0x77, 0x6f, + 0x75, 0x6c, 0x64, 0x20, 0x62, 0x65, 0x20, 0x69, + 0x74, 0x2e + } +}; + +static const unsigned char test_output[1][114] = +{ + { + 0xd3, 0x1a, 0x8d, 0x34, 0x64, 0x8e, 0x60, 0xdb, + 0x7b, 0x86, 0xaf, 0xbc, 0x53, 0xef, 0x7e, 0xc2, + 0xa4, 0xad, 0xed, 0x51, 0x29, 0x6e, 0x08, 0xfe, + 0xa9, 0xe2, 0xb5, 0xa7, 0x36, 0xee, 0x62, 0xd6, + 0x3d, 0xbe, 0xa4, 0x5e, 0x8c, 0xa9, 0x67, 0x12, + 0x82, 0xfa, 0xfb, 0x69, 0xda, 0x92, 0x72, 0x8b, + 0x1a, 0x71, 0xde, 0x0a, 0x9e, 0x06, 0x0b, 0x29, + 0x05, 0xd6, 0xa5, 0xb6, 0x7e, 0xcd, 0x3b, 0x36, + 0x92, 0xdd, 0xbd, 0x7f, 0x2d, 0x77, 0x8b, 0x8c, + 0x98, 0x03, 0xae, 0xe3, 0x28, 0x09, 0x1b, 0x58, + 0xfa, 0xb3, 0x24, 0xe4, 0xfa, 0xd6, 0x75, 0x94, + 0x55, 0x85, 0x80, 0x8b, 0x48, 0x31, 0xd7, 0xbc, + 0x3f, 0xf4, 0xde, 0xf0, 0x8e, 0x4b, 0x7a, 0x9d, + 0xe5, 0x76, 0xd2, 0x65, 0x86, 0xce, 0xc6, 0x4b, + 0x61, 0x16 + } +}; + +static const size_t test_input_len[1] = +{ + 114U +}; + +static const unsigned char test_mac[1][16] = +{ + { + 0x1a, 0xe1, 0x0b, 0x59, 0x4f, 0x09, 0xe2, 0x6a, + 0x7e, 0x90, 0x2e, 0xcb, 0xd0, 0x60, 0x06, 0x91 + } +}; + +/* Make sure no other definition is already present. */ +#undef ASSERT + +#define ASSERT(cond, args) \ + do \ + { \ + if (!(cond)) \ + { \ + if (verbose != 0) \ + mbedtls_printf args; \ + \ + return -1; \ + } \ + } \ + while (0) + +int mbedtls_chachapoly_self_test(int verbose) +{ + mbedtls_chachapoly_context ctx; + unsigned i; + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + unsigned char output[200]; + unsigned char mac[16]; + + for (i = 0U; i < 1U; i++) { + if (verbose != 0) { + mbedtls_printf(" ChaCha20-Poly1305 test %u ", i); + } + + mbedtls_chachapoly_init(&ctx); + + ret = mbedtls_chachapoly_setkey(&ctx, test_key[i]); + ASSERT(0 == ret, ("setkey() error code: %i\n", ret)); + + ret = mbedtls_chachapoly_encrypt_and_tag(&ctx, + test_input_len[i], + test_nonce[i], + test_aad[i], + test_aad_len[i], + test_input[i], + output, + mac); + + ASSERT(0 == ret, ("crypt_and_tag() error code: %i\n", ret)); + + ASSERT(0 == memcmp(output, test_output[i], test_input_len[i]), + ("failure (wrong output)\n")); + + ASSERT(0 == memcmp(mac, test_mac[i], 16U), + ("failure (wrong MAC)\n")); + + mbedtls_chachapoly_free(&ctx); + + if (verbose != 0) { + mbedtls_printf("passed\n"); + } + } + + if (verbose != 0) { + mbedtls_printf("\n"); + } + + return 0; +} + +#endif /* MBEDTLS_SELF_TEST */ + +#endif /* MBEDTLS_CHACHAPOLY_C */ |