/** * \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> #if defined(MBEDTLS_SELF_TEST) #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include <stdio.h> #define mbedtls_printf printf #endif /* MBEDTLS_PLATFORM_C */ #endif /* MBEDTLS_SELF_TEST */ #if !defined(MBEDTLS_CHACHAPOLY_ALT) /* Parameter validation macros */ #define CHACHAPOLY_VALIDATE_RET( cond ) \ MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA ) #define CHACHAPOLY_VALIDATE( cond ) \ MBEDTLS_INTERNAL_VALIDATE( cond ) #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 ) { CHACHAPOLY_VALIDATE( ctx != NULL ); 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; CHACHAPOLY_VALIDATE_RET( ctx != NULL ); CHACHAPOLY_VALIDATE_RET( key != NULL ); 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]; CHACHAPOLY_VALIDATE_RET( ctx != NULL ); CHACHAPOLY_VALIDATE_RET( nonce != NULL ); /* 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 ) { CHACHAPOLY_VALIDATE_RET( ctx != NULL ); CHACHAPOLY_VALIDATE_RET( aad_len == 0 || aad != NULL ); 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; CHACHAPOLY_VALIDATE_RET( ctx != NULL ); CHACHAPOLY_VALIDATE_RET( len == 0 || input != NULL ); CHACHAPOLY_VALIDATE_RET( len == 0 || output != NULL ); 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]; CHACHAPOLY_VALIDATE_RET( ctx != NULL ); CHACHAPOLY_VALIDATE_RET( mac != NULL ); 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. */ len_block[ 0] = (unsigned char)( ctx->aad_len ); len_block[ 1] = (unsigned char)( ctx->aad_len >> 8 ); len_block[ 2] = (unsigned char)( ctx->aad_len >> 16 ); len_block[ 3] = (unsigned char)( ctx->aad_len >> 24 ); len_block[ 4] = (unsigned char)( ctx->aad_len >> 32 ); len_block[ 5] = (unsigned char)( ctx->aad_len >> 40 ); len_block[ 6] = (unsigned char)( ctx->aad_len >> 48 ); len_block[ 7] = (unsigned char)( ctx->aad_len >> 56 ); len_block[ 8] = (unsigned char)( ctx->ciphertext_len ); len_block[ 9] = (unsigned char)( ctx->ciphertext_len >> 8 ); len_block[10] = (unsigned char)( ctx->ciphertext_len >> 16 ); len_block[11] = (unsigned char)( ctx->ciphertext_len >> 24 ); len_block[12] = (unsigned char)( ctx->ciphertext_len >> 32 ); len_block[13] = (unsigned char)( ctx->ciphertext_len >> 40 ); len_block[14] = (unsigned char)( ctx->ciphertext_len >> 48 ); len_block[15] = (unsigned char)( ctx->ciphertext_len >> 56 ); 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] ) { CHACHAPOLY_VALIDATE_RET( ctx != NULL ); CHACHAPOLY_VALIDATE_RET( nonce != NULL ); CHACHAPOLY_VALIDATE_RET( tag != NULL ); CHACHAPOLY_VALIDATE_RET( aad_len == 0 || aad != NULL ); CHACHAPOLY_VALIDATE_RET( length == 0 || input != NULL ); CHACHAPOLY_VALIDATE_RET( length == 0 || output != NULL ); 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; CHACHAPOLY_VALIDATE_RET( ctx != NULL ); CHACHAPOLY_VALIDATE_RET( nonce != NULL ); CHACHAPOLY_VALIDATE_RET( tag != NULL ); CHACHAPOLY_VALIDATE_RET( aad_len == 0 || aad != NULL ); CHACHAPOLY_VALIDATE_RET( length == 0 || input != NULL ); CHACHAPOLY_VALIDATE_RET( length == 0 || output != NULL ); 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 */