/** * \file chacha20.c * * \brief ChaCha20 cipher. * * \author Daniel King * * 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_CHACHA20_C) #include "mbedtls/chacha20.h" #include "mbedtls/platform_util.h" #include "mbedtls/error.h" #include #include #include "mbedtls/platform.h" #if !defined(MBEDTLS_CHACHA20_ALT) #define ROTL32( value, amount ) \ ( (uint32_t) ( (value) << (amount) ) | ( (value) >> ( 32 - (amount) ) ) ) #define CHACHA20_CTR_INDEX ( 12U ) #define CHACHA20_BLOCK_SIZE_BYTES ( 4U * 16U ) /** * \brief ChaCha20 quarter round operation. * * The quarter round is defined as follows (from RFC 7539): * 1. a += b; d ^= a; d <<<= 16; * 2. c += d; b ^= c; b <<<= 12; * 3. a += b; d ^= a; d <<<= 8; * 4. c += d; b ^= c; b <<<= 7; * * \param state ChaCha20 state to modify. * \param a The index of 'a' in the state. * \param b The index of 'b' in the state. * \param c The index of 'c' in the state. * \param d The index of 'd' in the state. */ static inline void chacha20_quarter_round( uint32_t state[16], size_t a, size_t b, size_t c, size_t d ) { /* a += b; d ^= a; d <<<= 16; */ state[a] += state[b]; state[d] ^= state[a]; state[d] = ROTL32( state[d], 16 ); /* c += d; b ^= c; b <<<= 12 */ state[c] += state[d]; state[b] ^= state[c]; state[b] = ROTL32( state[b], 12 ); /* a += b; d ^= a; d <<<= 8; */ state[a] += state[b]; state[d] ^= state[a]; state[d] = ROTL32( state[d], 8 ); /* c += d; b ^= c; b <<<= 7; */ state[c] += state[d]; state[b] ^= state[c]; state[b] = ROTL32( state[b], 7 ); } /** * \brief Perform the ChaCha20 inner block operation. * * This function performs two rounds: the column round and the * diagonal round. * * \param state The ChaCha20 state to update. */ static void chacha20_inner_block( uint32_t state[16] ) { chacha20_quarter_round( state, 0, 4, 8, 12 ); chacha20_quarter_round( state, 1, 5, 9, 13 ); chacha20_quarter_round( state, 2, 6, 10, 14 ); chacha20_quarter_round( state, 3, 7, 11, 15 ); chacha20_quarter_round( state, 0, 5, 10, 15 ); chacha20_quarter_round( state, 1, 6, 11, 12 ); chacha20_quarter_round( state, 2, 7, 8, 13 ); chacha20_quarter_round( state, 3, 4, 9, 14 ); } /** * \brief Generates a keystream block. * * \param initial_state The initial ChaCha20 state (key, nonce, counter). * \param keystream Generated keystream bytes are written to this buffer. */ static void chacha20_block( const uint32_t initial_state[16], unsigned char keystream[64] ) { uint32_t working_state[16]; size_t i; memcpy( working_state, initial_state, CHACHA20_BLOCK_SIZE_BYTES ); for( i = 0U; i < 10U; i++ ) chacha20_inner_block( working_state ); working_state[ 0] += initial_state[ 0]; working_state[ 1] += initial_state[ 1]; working_state[ 2] += initial_state[ 2]; working_state[ 3] += initial_state[ 3]; working_state[ 4] += initial_state[ 4]; working_state[ 5] += initial_state[ 5]; working_state[ 6] += initial_state[ 6]; working_state[ 7] += initial_state[ 7]; working_state[ 8] += initial_state[ 8]; working_state[ 9] += initial_state[ 9]; working_state[10] += initial_state[10]; working_state[11] += initial_state[11]; working_state[12] += initial_state[12]; working_state[13] += initial_state[13]; working_state[14] += initial_state[14]; working_state[15] += initial_state[15]; for( i = 0U; i < 16; i++ ) { size_t offset = i * 4U; MBEDTLS_PUT_UINT32_LE(working_state[i], keystream, offset); } mbedtls_platform_zeroize( working_state, sizeof( working_state ) ); } void mbedtls_chacha20_init( mbedtls_chacha20_context *ctx ) { mbedtls_platform_zeroize( ctx->state, sizeof( ctx->state ) ); mbedtls_platform_zeroize( ctx->keystream8, sizeof( ctx->keystream8 ) ); /* Initially, there's no keystream bytes available */ ctx->keystream_bytes_used = CHACHA20_BLOCK_SIZE_BYTES; } void mbedtls_chacha20_free( mbedtls_chacha20_context *ctx ) { if( ctx != NULL ) { mbedtls_platform_zeroize( ctx, sizeof( mbedtls_chacha20_context ) ); } } int mbedtls_chacha20_setkey( mbedtls_chacha20_context *ctx, const unsigned char key[32] ) { /* ChaCha20 constants - the string "expand 32-byte k" */ ctx->state[0] = 0x61707865; ctx->state[1] = 0x3320646e; ctx->state[2] = 0x79622d32; ctx->state[3] = 0x6b206574; /* Set key */ ctx->state[4] = MBEDTLS_GET_UINT32_LE( key, 0 ); ctx->state[5] = MBEDTLS_GET_UINT32_LE( key, 4 ); ctx->state[6] = MBEDTLS_GET_UINT32_LE( key, 8 ); ctx->state[7] = MBEDTLS_GET_UINT32_LE( key, 12 ); ctx->state[8] = MBEDTLS_GET_UINT32_LE( key, 16 ); ctx->state[9] = MBEDTLS_GET_UINT32_LE( key, 20 ); ctx->state[10] = MBEDTLS_GET_UINT32_LE( key, 24 ); ctx->state[11] = MBEDTLS_GET_UINT32_LE( key, 28 ); return( 0 ); } int mbedtls_chacha20_starts( mbedtls_chacha20_context* ctx, const unsigned char nonce[12], uint32_t counter ) { /* Counter */ ctx->state[12] = counter; /* Nonce */ ctx->state[13] = MBEDTLS_GET_UINT32_LE( nonce, 0 ); ctx->state[14] = MBEDTLS_GET_UINT32_LE( nonce, 4 ); ctx->state[15] = MBEDTLS_GET_UINT32_LE( nonce, 8 ); mbedtls_platform_zeroize( ctx->keystream8, sizeof( ctx->keystream8 ) ); /* Initially, there's no keystream bytes available */ ctx->keystream_bytes_used = CHACHA20_BLOCK_SIZE_BYTES; return( 0 ); } int mbedtls_chacha20_update( mbedtls_chacha20_context *ctx, size_t size, const unsigned char *input, unsigned char *output ) { size_t offset = 0U; /* Use leftover keystream bytes, if available */ while( size > 0U && ctx->keystream_bytes_used < CHACHA20_BLOCK_SIZE_BYTES ) { output[offset] = input[offset] ^ ctx->keystream8[ctx->keystream_bytes_used]; ctx->keystream_bytes_used++; offset++; size--; } /* Process full blocks */ while( size >= CHACHA20_BLOCK_SIZE_BYTES ) { /* Generate new keystream block and increment counter */ chacha20_block( ctx->state, ctx->keystream8 ); ctx->state[CHACHA20_CTR_INDEX]++; mbedtls_xor( output + offset, input + offset, ctx->keystream8, 64U ); offset += CHACHA20_BLOCK_SIZE_BYTES; size -= CHACHA20_BLOCK_SIZE_BYTES; } /* Last (partial) block */ if( size > 0U ) { /* Generate new keystream block and increment counter */ chacha20_block( ctx->state, ctx->keystream8 ); ctx->state[CHACHA20_CTR_INDEX]++; mbedtls_xor( output + offset, input + offset, ctx->keystream8, size ); ctx->keystream_bytes_used = size; } return( 0 ); } int mbedtls_chacha20_crypt( const unsigned char key[32], const unsigned char nonce[12], uint32_t counter, size_t data_len, const unsigned char* input, unsigned char* output ) { mbedtls_chacha20_context ctx; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; mbedtls_chacha20_init( &ctx ); ret = mbedtls_chacha20_setkey( &ctx, key ); if( ret != 0 ) goto cleanup; ret = mbedtls_chacha20_starts( &ctx, nonce, counter ); if( ret != 0 ) goto cleanup; ret = mbedtls_chacha20_update( &ctx, data_len, input, output ); cleanup: mbedtls_chacha20_free( &ctx ); return( ret ); } #endif /* !MBEDTLS_CHACHA20_ALT */ #if defined(MBEDTLS_SELF_TEST) static const unsigned char test_keys[2][32] = { { 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, 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, 0x01 } }; static const unsigned char test_nonces[2][12] = { { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 } }; static const uint32_t test_counters[2] = { 0U, 1U }; static const unsigned char test_input[2][375] = { { 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, 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 }, { 0x41, 0x6e, 0x79, 0x20, 0x73, 0x75, 0x62, 0x6d, 0x69, 0x73, 0x73, 0x69, 0x6f, 0x6e, 0x20, 0x74, 0x6f, 0x20, 0x74, 0x68, 0x65, 0x20, 0x49, 0x45, 0x54, 0x46, 0x20, 0x69, 0x6e, 0x74, 0x65, 0x6e, 0x64, 0x65, 0x64, 0x20, 0x62, 0x79, 0x20, 0x74, 0x68, 0x65, 0x20, 0x43, 0x6f, 0x6e, 0x74, 0x72, 0x69, 0x62, 0x75, 0x74, 0x6f, 0x72, 0x20, 0x66, 0x6f, 0x72, 0x20, 0x70, 0x75, 0x62, 0x6c, 0x69, 0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x20, 0x61, 0x73, 0x20, 0x61, 0x6c, 0x6c, 0x20, 0x6f, 0x72, 0x20, 0x70, 0x61, 0x72, 0x74, 0x20, 0x6f, 0x66, 0x20, 0x61, 0x6e, 0x20, 0x49, 0x45, 0x54, 0x46, 0x20, 0x49, 0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65, 0x74, 0x2d, 0x44, 0x72, 0x61, 0x66, 0x74, 0x20, 0x6f, 0x72, 0x20, 0x52, 0x46, 0x43, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x61, 0x6e, 0x79, 0x20, 0x73, 0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x20, 0x6d, 0x61, 0x64, 0x65, 0x20, 0x77, 0x69, 0x74, 0x68, 0x69, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63, 0x6f, 0x6e, 0x74, 0x65, 0x78, 0x74, 0x20, 0x6f, 0x66, 0x20, 0x61, 0x6e, 0x20, 0x49, 0x45, 0x54, 0x46, 0x20, 0x61, 0x63, 0x74, 0x69, 0x76, 0x69, 0x74, 0x79, 0x20, 0x69, 0x73, 0x20, 0x63, 0x6f, 0x6e, 0x73, 0x69, 0x64, 0x65, 0x72, 0x65, 0x64, 0x20, 0x61, 0x6e, 0x20, 0x22, 0x49, 0x45, 0x54, 0x46, 0x20, 0x43, 0x6f, 0x6e, 0x74, 0x72, 0x69, 0x62, 0x75, 0x74, 0x69, 0x6f, 0x6e, 0x22, 0x2e, 0x20, 0x53, 0x75, 0x63, 0x68, 0x20, 0x73, 0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x73, 0x20, 0x69, 0x6e, 0x63, 0x6c, 0x75, 0x64, 0x65, 0x20, 0x6f, 0x72, 0x61, 0x6c, 0x20, 0x73, 0x74, 0x61, 0x74, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x73, 0x20, 0x69, 0x6e, 0x20, 0x49, 0x45, 0x54, 0x46, 0x20, 0x73, 0x65, 0x73, 0x73, 0x69, 0x6f, 0x6e, 0x73, 0x2c, 0x20, 0x61, 0x73, 0x20, 0x77, 0x65, 0x6c, 0x6c, 0x20, 0x61, 0x73, 0x20, 0x77, 0x72, 0x69, 0x74, 0x74, 0x65, 0x6e, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x65, 0x6c, 0x65, 0x63, 0x74, 0x72, 0x6f, 0x6e, 0x69, 0x63, 0x20, 0x63, 0x6f, 0x6d, 0x6d, 0x75, 0x6e, 0x69, 0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x73, 0x20, 0x6d, 0x61, 0x64, 0x65, 0x20, 0x61, 0x74, 0x20, 0x61, 0x6e, 0x79, 0x20, 0x74, 0x69, 0x6d, 0x65, 0x20, 0x6f, 0x72, 0x20, 0x70, 0x6c, 0x61, 0x63, 0x65, 0x2c, 0x20, 0x77, 0x68, 0x69, 0x63, 0x68, 0x20, 0x61, 0x72, 0x65, 0x20, 0x61, 0x64, 0x64, 0x72, 0x65, 0x73, 0x73, 0x65, 0x64, 0x20, 0x74, 0x6f } }; static const unsigned char test_output[2][375] = { { 0x76, 0xb8, 0xe0, 0xad, 0xa0, 0xf1, 0x3d, 0x90, 0x40, 0x5d, 0x6a, 0xe5, 0x53, 0x86, 0xbd, 0x28, 0xbd, 0xd2, 0x19, 0xb8, 0xa0, 0x8d, 0xed, 0x1a, 0xa8, 0x36, 0xef, 0xcc, 0x8b, 0x77, 0x0d, 0xc7, 0xda, 0x41, 0x59, 0x7c, 0x51, 0x57, 0x48, 0x8d, 0x77, 0x24, 0xe0, 0x3f, 0xb8, 0xd8, 0x4a, 0x37, 0x6a, 0x43, 0xb8, 0xf4, 0x15, 0x18, 0xa1, 0x1c, 0xc3, 0x87, 0xb6, 0x69, 0xb2, 0xee, 0x65, 0x86 }, { 0xa3, 0xfb, 0xf0, 0x7d, 0xf3, 0xfa, 0x2f, 0xde, 0x4f, 0x37, 0x6c, 0xa2, 0x3e, 0x82, 0x73, 0x70, 0x41, 0x60, 0x5d, 0x9f, 0x4f, 0x4f, 0x57, 0xbd, 0x8c, 0xff, 0x2c, 0x1d, 0x4b, 0x79, 0x55, 0xec, 0x2a, 0x97, 0x94, 0x8b, 0xd3, 0x72, 0x29, 0x15, 0xc8, 0xf3, 0xd3, 0x37, 0xf7, 0xd3, 0x70, 0x05, 0x0e, 0x9e, 0x96, 0xd6, 0x47, 0xb7, 0xc3, 0x9f, 0x56, 0xe0, 0x31, 0xca, 0x5e, 0xb6, 0x25, 0x0d, 0x40, 0x42, 0xe0, 0x27, 0x85, 0xec, 0xec, 0xfa, 0x4b, 0x4b, 0xb5, 0xe8, 0xea, 0xd0, 0x44, 0x0e, 0x20, 0xb6, 0xe8, 0xdb, 0x09, 0xd8, 0x81, 0xa7, 0xc6, 0x13, 0x2f, 0x42, 0x0e, 0x52, 0x79, 0x50, 0x42, 0xbd, 0xfa, 0x77, 0x73, 0xd8, 0xa9, 0x05, 0x14, 0x47, 0xb3, 0x29, 0x1c, 0xe1, 0x41, 0x1c, 0x68, 0x04, 0x65, 0x55, 0x2a, 0xa6, 0xc4, 0x05, 0xb7, 0x76, 0x4d, 0x5e, 0x87, 0xbe, 0xa8, 0x5a, 0xd0, 0x0f, 0x84, 0x49, 0xed, 0x8f, 0x72, 0xd0, 0xd6, 0x62, 0xab, 0x05, 0x26, 0x91, 0xca, 0x66, 0x42, 0x4b, 0xc8, 0x6d, 0x2d, 0xf8, 0x0e, 0xa4, 0x1f, 0x43, 0xab, 0xf9, 0x37, 0xd3, 0x25, 0x9d, 0xc4, 0xb2, 0xd0, 0xdf, 0xb4, 0x8a, 0x6c, 0x91, 0x39, 0xdd, 0xd7, 0xf7, 0x69, 0x66, 0xe9, 0x28, 0xe6, 0x35, 0x55, 0x3b, 0xa7, 0x6c, 0x5c, 0x87, 0x9d, 0x7b, 0x35, 0xd4, 0x9e, 0xb2, 0xe6, 0x2b, 0x08, 0x71, 0xcd, 0xac, 0x63, 0x89, 0x39, 0xe2, 0x5e, 0x8a, 0x1e, 0x0e, 0xf9, 0xd5, 0x28, 0x0f, 0xa8, 0xca, 0x32, 0x8b, 0x35, 0x1c, 0x3c, 0x76, 0x59, 0x89, 0xcb, 0xcf, 0x3d, 0xaa, 0x8b, 0x6c, 0xcc, 0x3a, 0xaf, 0x9f, 0x39, 0x79, 0xc9, 0x2b, 0x37, 0x20, 0xfc, 0x88, 0xdc, 0x95, 0xed, 0x84, 0xa1, 0xbe, 0x05, 0x9c, 0x64, 0x99, 0xb9, 0xfd, 0xa2, 0x36, 0xe7, 0xe8, 0x18, 0xb0, 0x4b, 0x0b, 0xc3, 0x9c, 0x1e, 0x87, 0x6b, 0x19, 0x3b, 0xfe, 0x55, 0x69, 0x75, 0x3f, 0x88, 0x12, 0x8c, 0xc0, 0x8a, 0xaa, 0x9b, 0x63, 0xd1, 0xa1, 0x6f, 0x80, 0xef, 0x25, 0x54, 0xd7, 0x18, 0x9c, 0x41, 0x1f, 0x58, 0x69, 0xca, 0x52, 0xc5, 0xb8, 0x3f, 0xa3, 0x6f, 0xf2, 0x16, 0xb9, 0xc1, 0xd3, 0x00, 0x62, 0xbe, 0xbc, 0xfd, 0x2d, 0xc5, 0xbc, 0xe0, 0x91, 0x19, 0x34, 0xfd, 0xa7, 0x9a, 0x86, 0xf6, 0xe6, 0x98, 0xce, 0xd7, 0x59, 0xc3, 0xff, 0x9b, 0x64, 0x77, 0x33, 0x8f, 0x3d, 0xa4, 0xf9, 0xcd, 0x85, 0x14, 0xea, 0x99, 0x82, 0xcc, 0xaf, 0xb3, 0x41, 0xb2, 0x38, 0x4d, 0xd9, 0x02, 0xf3, 0xd1, 0xab, 0x7a, 0xc6, 0x1d, 0xd2, 0x9c, 0x6f, 0x21, 0xba, 0x5b, 0x86, 0x2f, 0x37, 0x30, 0xe3, 0x7c, 0xfd, 0xc4, 0xfd, 0x80, 0x6c, 0x22, 0xf2, 0x21 } }; static const size_t test_lengths[2] = { 64U, 375U }; /* 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_chacha20_self_test( int verbose ) { unsigned char output[381]; unsigned i; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; for( i = 0U; i < 2U; i++ ) { if( verbose != 0 ) mbedtls_printf( " ChaCha20 test %u ", i ); ret = mbedtls_chacha20_crypt( test_keys[i], test_nonces[i], test_counters[i], test_lengths[i], test_input[i], output ); ASSERT( 0 == ret, ( "error code: %i\n", ret ) ); ASSERT( 0 == memcmp( output, test_output[i], test_lengths[i] ), ( "failed (output)\n" ) ); if( verbose != 0 ) mbedtls_printf( "passed\n" ); } if( verbose != 0 ) mbedtls_printf( "\n" ); return( 0 ); } #endif /* MBEDTLS_SELF_TEST */ #endif /* !MBEDTLS_CHACHA20_C */