diff options
Diffstat (limited to 'library/chachapoly.c')
| -rw-r--r-- | library/chachapoly.c | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/library/chachapoly.c b/library/chachapoly.c new file mode 100644 index 000000000..e283853a4 --- /dev/null +++ b/library/chachapoly.c @@ -0,0 +1,484 @@ +/** + * \file chachapoly.c + * + * \brief ChaCha20-Poly1305 AEAD construction based on RFC 7539. + * + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 + * + * Licensed under the Apache License, Version 2.0 (the "License"); you may + * not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +#include "common.h" + +#if defined(MBEDTLS_CHACHAPOLY_C) + +#include "mbedtls/chachapoly.h" +#include "mbedtls/platform_util.h" +#include "mbedtls/error.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]; + size_t i; + 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" */ + for( diff = 0, i = 0; i < sizeof( check_tag ); i++ ) + diff |= tag[i] ^ check_tag[i]; + + 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 */ |