88 lines
3.0 KiB
C
88 lines
3.0 KiB
C
#ifndef AWS_CAL_HMAC_H_
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#define AWS_CAL_HMAC_H_
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/**
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* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
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* SPDX-License-Identifier: Apache-2.0.
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*/
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#include <aws/cal/exports.h>
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#include <aws/common/byte_buf.h>
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#include <aws/common/common.h>
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AWS_PUSH_SANE_WARNING_LEVEL
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#define AWS_SHA256_HMAC_LEN 32
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struct aws_hmac;
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struct aws_hmac_vtable {
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const char *alg_name;
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const char *provider;
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void (*destroy)(struct aws_hmac *hmac);
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int (*update)(struct aws_hmac *hmac, const struct aws_byte_cursor *buf);
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int (*finalize)(struct aws_hmac *hmac, struct aws_byte_buf *out);
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};
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struct aws_hmac {
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struct aws_allocator *allocator;
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struct aws_hmac_vtable *vtable;
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size_t digest_size;
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bool good;
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void *impl;
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};
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typedef struct aws_hmac *(aws_hmac_new_fn)(struct aws_allocator *allocator, const struct aws_byte_cursor *secret);
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AWS_EXTERN_C_BEGIN
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/**
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* Allocates and initializes a sha256 hmac instance. Secret is the key to be
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* used for the hmac process.
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*/
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AWS_CAL_API struct aws_hmac *aws_sha256_hmac_new(struct aws_allocator *allocator, const struct aws_byte_cursor *secret);
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/**
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* Cleans up and deallocates hmac.
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*/
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AWS_CAL_API void aws_hmac_destroy(struct aws_hmac *hmac);
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/**
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* Updates the running hmac with to_hash. this can be called multiple times.
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*/
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AWS_CAL_API int aws_hmac_update(struct aws_hmac *hmac, const struct aws_byte_cursor *to_hmac);
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/**
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* Completes the hmac computation and writes the final digest to output.
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* Allocation of output is the caller's responsibility. If you specify
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* truncate_to to something other than 0, the output will be truncated to that
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* number of bytes. For example if you want a SHA256 digest as the first 16
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* bytes, set truncate_to to 16. If you want the full digest size, just set this
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* to 0.
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*/
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AWS_CAL_API int aws_hmac_finalize(struct aws_hmac *hmac, struct aws_byte_buf *output, size_t truncate_to);
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/**
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* Computes the sha256 hmac over input and writes the digest output to 'output'.
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* Use this if you don't need to stream the data you're hashing and you can load
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* the entire input to hash into memory. If you specify truncate_to to something
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* other than 0, the output will be truncated to that number of bytes. For
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* example if you want a SHA256 HMAC digest as the first 16 bytes, set
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* truncate_to to 16. If you want the full digest size, just set this to 0.
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*/
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AWS_CAL_API int aws_sha256_hmac_compute(
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struct aws_allocator *allocator,
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const struct aws_byte_cursor *secret,
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const struct aws_byte_cursor *to_hmac,
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struct aws_byte_buf *output,
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size_t truncate_to);
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/**
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* Set the implementation of sha256 hmac to use. If you compiled without
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* BYO_CRYPTO, you do not need to call this. However, if use this, we will
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* honor it, regardless of compile options. This may be useful for testing
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* purposes. If you did set BYO_CRYPTO, and you do not call this function
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* you will segfault.
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*/
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AWS_CAL_API void aws_set_sha256_hmac_new_fn(aws_hmac_new_fn *fn);
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AWS_EXTERN_C_END
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AWS_POP_SANE_WARNING_LEVEL
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#endif /* AWS_CAL_HASH_H_ */
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