diff options
Diffstat (limited to 'libs/libaxolotl/src/hkdf.c')
| -rw-r--r-- | libs/libaxolotl/src/hkdf.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/libs/libaxolotl/src/hkdf.c b/libs/libaxolotl/src/hkdf.c new file mode 100644 index 0000000000..63b35ddaa4 --- /dev/null +++ b/libs/libaxolotl/src/hkdf.c @@ -0,0 +1,256 @@ +#include "hkdf.h" + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <math.h> +#include <assert.h> + +#include "axolotl_internal.h" + +#define HASH_OUTPUT_SIZE 32 + +#define MIN(a,b) (((a)<(b))?(a):(b)) +#define MAX(a,b) (((a)>(b))?(a):(b)) + +struct hkdf_context +{ + axolotl_type_base base; + axolotl_context *global_context; + int iteration_start_offset; +}; + +int hkdf_create(hkdf_context **context, int message_version, axolotl_context *global_context) +{ + assert(global_context); + *context = malloc(sizeof(hkdf_context)); + if(!(*context)) { + return AX_ERR_NOMEM; + } + + memset(*context, 0, sizeof(hkdf_context)); + + AXOLOTL_INIT(*context, hkdf_destroy); + (*context)->global_context = global_context; + + if(message_version == 2) { + (*context)->iteration_start_offset = 0; + } + else if(message_version == 3) { + (*context)->iteration_start_offset = 1; + } + else { + free(*context); + return AX_ERR_INVAL; + } + + return 0; +} + +ssize_t hkdf_extract(hkdf_context *context, + uint8_t **output, + const uint8_t *salt, size_t salt_len, + const uint8_t *input_key_material, size_t input_key_material_len) +{ + int result = 0; + axolotl_buffer *mac_buffer = 0; + uint8_t *mac = 0; + size_t mac_len = 0; + void *hmac_context; + + assert(context); + + result = axolotl_hmac_sha256_init(context->global_context, + &hmac_context, salt, salt_len); + if(result < 0) { + goto complete; + } + + result = axolotl_hmac_sha256_update(context->global_context, + hmac_context, input_key_material, input_key_material_len); + if(result < 0) { + goto complete; + } + + result = axolotl_hmac_sha256_final(context->global_context, + hmac_context, &mac_buffer); + if(result < 0) { + goto complete; + } + + mac_len = axolotl_buffer_len(mac_buffer); + mac = malloc(mac_len); + if(!mac) { + result = AX_ERR_NOMEM; + goto complete; + } + + memcpy(mac, axolotl_buffer_data(mac_buffer), mac_len); + +complete: + axolotl_hmac_sha256_cleanup(context->global_context, hmac_context); + axolotl_buffer_free(mac_buffer); + + if(result >= 0) { + *output = mac; + return (ssize_t)mac_len; + } + else { + return result; + } +} + +ssize_t hkdf_expand(hkdf_context *context, + uint8_t **output, + const uint8_t *prk, size_t prk_len, + const uint8_t *info, size_t info_len, + size_t output_len) +{ + int iterations = (int)ceil((double)output_len / (double)HASH_OUTPUT_SIZE); + size_t remaining_len = output_len; + axolotl_buffer *step_buffer = 0; + size_t step_size = 0; + uint8_t *result_buf = 0; + size_t result_buf_len = 0; + void *hmac_context = 0; + int result = 0; + uint8_t i; + + assert(context); + + for(i = context->iteration_start_offset; i < iterations + context->iteration_start_offset; i++) { + result = axolotl_hmac_sha256_init(context->global_context, + &hmac_context, prk, prk_len); + if(result < 0) { + goto complete; + } + + if(step_buffer) { + result = axolotl_hmac_sha256_update(context->global_context, + hmac_context, + axolotl_buffer_data(step_buffer), + axolotl_buffer_len(step_buffer)); + if(result < 0) { + goto complete; + } + axolotl_buffer_free(step_buffer); + step_buffer = 0; + } + + if(info) { + result = axolotl_hmac_sha256_update(context->global_context, + hmac_context, info, info_len); + if(result < 0) { + goto complete; + } + } + + result = axolotl_hmac_sha256_update(context->global_context, + hmac_context, &i, sizeof(uint8_t)); + if(result < 0) { + goto complete; + } + + result = axolotl_hmac_sha256_final(context->global_context, + hmac_context, &step_buffer); + if(result < 0) { + goto complete; + } + + axolotl_hmac_sha256_cleanup(context->global_context, hmac_context); + hmac_context = 0; + + step_size = MIN(remaining_len, axolotl_buffer_len(step_buffer)); + + if(!result_buf) { + result_buf = malloc(step_size); + if(!result_buf) { + result = AX_ERR_NOMEM; + goto complete; + } + memcpy(result_buf, axolotl_buffer_data(step_buffer), step_size); + result_buf_len = step_size; + } + else { + uint8_t *tmp_buf = realloc(result_buf, result_buf_len + step_size); + if(!tmp_buf) { + result = AX_ERR_NOMEM; + goto complete; + } + result_buf = tmp_buf; + memcpy(result_buf + result_buf_len, axolotl_buffer_data(step_buffer), step_size); + result_buf_len += step_size; + } + remaining_len -= step_size; + } + +complete: + if(hmac_context) { + axolotl_hmac_sha256_cleanup(context->global_context, hmac_context); + } + axolotl_buffer_free(step_buffer); + if(result < 0) { + free(result_buf); + return result; + } + else { + *output = result_buf; + return (ssize_t)result_buf_len; + } +} + +ssize_t hkdf_derive_secrets(hkdf_context *context, + uint8_t **output, + const uint8_t *input_key_material, size_t input_key_material_len, + const uint8_t *salt, size_t salt_len, + const uint8_t *info, size_t info_len, + size_t output_len) +{ + ssize_t result = 0; + uint8_t *prk = 0; + ssize_t prk_len = 0; + + assert(context); + + prk_len = hkdf_extract(context, &prk, salt, salt_len, input_key_material, input_key_material_len); + if(prk_len < 0) { + axolotl_log(context->global_context, AX_LOG_ERROR, "hkdf_extract error: %d", prk_len); + return prk_len; + } + + result = hkdf_expand(context, output, prk, (size_t)prk_len, info, info_len, output_len); + + if(prk) { + free(prk); + } + + return result; +} + +int hkdf_compare(const hkdf_context *context1, const hkdf_context *context2) +{ + if(context1 == context2) { + return 0; + } + else if(context1 == 0 && context2 != 0) { + return -1; + } + else if(context1 != 0 && context2 == 0) { + return 1; + } + else if(context1->iteration_start_offset < context2->iteration_start_offset) { + return -1; + } + else if(context1->iteration_start_offset > context2->iteration_start_offset) { + return 1; + } + else { + return 0; + } +} + +void hkdf_destroy(axolotl_type_base *type) +{ + hkdf_context *context = (hkdf_context *)type; + free(context); +} |