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/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
#include <aws/cal/hmac.h>
#include <aws/common/thread.h>
#include <windows.h>
#include <bcrypt.h>
#include <winerror.h>
static BCRYPT_ALG_HANDLE s_sha256_hmac_alg = NULL;
static size_t s_sha256_hmac_obj_len = 0;
static aws_thread_once s_sha256_hmac_once = AWS_THREAD_ONCE_STATIC_INIT;
static void s_destroy(struct aws_hmac *hash);
static int s_update(struct aws_hmac *hash, const struct aws_byte_cursor *to_hash);
static int s_finalize(struct aws_hmac *hash, struct aws_byte_buf *output);
static struct aws_hmac_vtable s_sha256_hmac_vtable = {
.destroy = s_destroy,
.update = s_update,
.finalize = s_finalize,
.alg_name = "SHA256 HMAC",
.provider = "Windows CNG",
};
struct bcrypt_hmac_handle {
struct aws_hmac hmac;
BCRYPT_HASH_HANDLE hash_handle;
uint8_t *hash_obj;
};
static void s_load_alg_handle(void *user_data) {
(void)user_data;
/* this function is incredibly slow, LET IT LEAK*/
BCryptOpenAlgorithmProvider(
&s_sha256_hmac_alg, BCRYPT_SHA256_ALGORITHM, MS_PRIMITIVE_PROVIDER, BCRYPT_ALG_HANDLE_HMAC_FLAG);
AWS_ASSERT(s_sha256_hmac_alg);
DWORD result_length = 0;
BCryptGetProperty(
s_sha256_hmac_alg,
BCRYPT_OBJECT_LENGTH,
(PBYTE)&s_sha256_hmac_obj_len,
sizeof(s_sha256_hmac_obj_len),
&result_length,
0);
}
struct aws_hmac *aws_sha256_hmac_default_new(struct aws_allocator *allocator, const struct aws_byte_cursor *secret) {
aws_thread_call_once(&s_sha256_hmac_once, s_load_alg_handle, NULL);
struct bcrypt_hmac_handle *bcrypt_hmac;
uint8_t *hash_obj;
aws_mem_acquire_many(
allocator, 2, &bcrypt_hmac, sizeof(struct bcrypt_hmac_handle), &hash_obj, s_sha256_hmac_obj_len);
if (!bcrypt_hmac) {
return NULL;
}
AWS_ZERO_STRUCT(*bcrypt_hmac);
bcrypt_hmac->hmac.allocator = allocator;
bcrypt_hmac->hmac.vtable = &s_sha256_hmac_vtable;
bcrypt_hmac->hmac.impl = bcrypt_hmac;
bcrypt_hmac->hmac.digest_size = AWS_SHA256_HMAC_LEN;
bcrypt_hmac->hmac.good = true;
bcrypt_hmac->hash_obj = hash_obj;
NTSTATUS status = BCryptCreateHash(
s_sha256_hmac_alg,
&bcrypt_hmac->hash_handle,
bcrypt_hmac->hash_obj,
(ULONG)s_sha256_hmac_obj_len,
secret->ptr,
(ULONG)secret->len,
0);
if (((NTSTATUS)status) < 0) {
aws_mem_release(allocator, bcrypt_hmac);
return NULL;
}
return &bcrypt_hmac->hmac;
}
static void s_destroy(struct aws_hmac *hmac) {
struct bcrypt_hmac_handle *ctx = hmac->impl;
BCryptDestroyHash(ctx->hash_handle);
aws_mem_release(hmac->allocator, ctx);
}
static int s_update(struct aws_hmac *hmac, const struct aws_byte_cursor *to_hash) {
if (!hmac->good) {
return aws_raise_error(AWS_ERROR_INVALID_STATE);
}
struct bcrypt_hmac_handle *ctx = hmac->impl;
NTSTATUS status = BCryptHashData(ctx->hash_handle, to_hash->ptr, (ULONG)to_hash->len, 0);
if (((NTSTATUS)status) < 0) {
hmac->good = false;
return aws_raise_error(AWS_ERROR_INVALID_ARGUMENT);
}
return AWS_OP_SUCCESS;
}
static int s_finalize(struct aws_hmac *hmac, struct aws_byte_buf *output) {
if (!hmac->good) {
return aws_raise_error(AWS_ERROR_INVALID_STATE);
}
struct bcrypt_hmac_handle *ctx = hmac->impl;
size_t buffer_len = output->capacity - output->len;
if (buffer_len < hmac->digest_size) {
return aws_raise_error(AWS_ERROR_SHORT_BUFFER);
}
NTSTATUS status = BCryptFinishHash(ctx->hash_handle, output->buffer + output->len, (ULONG)hmac->digest_size, 0);
hmac->good = false;
if (((NTSTATUS)status) < 0) {
return aws_raise_error(AWS_ERROR_INVALID_ARGUMENT);
}
output->len += hmac->digest_size;
return AWS_OP_SUCCESS;
}
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