Lesson 35 - Get Compute Auth Token Working
This commit is contained in:
Norman Lansing
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#pragma once
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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/hmac.h>
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#include <aws/crt/Exports.h>
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#include <aws/crt/Types.h>
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struct aws_hmac;
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namespace Aws
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{
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namespace Crt
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{
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namespace Crypto
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{
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static const size_t SHA256_HMAC_DIGEST_SIZE = 32;
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/**
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* Computes a SHA256 HMAC with secret over input, and writes the digest to output. If truncateTo is
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* non-zero, the digest will be truncated to the value of truncateTo. Returns true on success. If this
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* function fails, Aws::Crt::LastError() will contain the error that occurred. Unless you're using
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* 'truncateTo', output should have a minimum capacity of SHA256_HMAC_DIGEST_SIZE.
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*/
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bool AWS_CRT_CPP_API ComputeSHA256HMAC(
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Allocator *allocator,
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const ByteCursor &secret,
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const ByteCursor &input,
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ByteBuf &output,
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size_t truncateTo = 0) noexcept;
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/**
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* Computes a SHA256 HMAC using the default allocator with secret over input, and writes the digest to
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* output. If truncateTo is non-zero, the digest will be truncated to the value of truncateTo. Returns true
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* on success. If this function fails, Aws::Crt::LastError() will contain the error that occurred. Unless
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* you're using 'truncateTo', output should have a minimum capacity of SHA256_HMAC_DIGEST_SIZE.
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*/
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bool AWS_CRT_CPP_API ComputeSHA256HMAC(
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const ByteCursor &secret,
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const ByteCursor &input,
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ByteBuf &output,
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size_t truncateTo = 0) noexcept;
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/**
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* Streaming HMAC object. The typical use case is for computing the HMAC of an object that is too large to
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* load into memory. You can call Update() multiple times as you load chunks of data into memory. When
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* you're finished simply call Digest(). After Digest() is called, this object is no longer usable.
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*/
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class AWS_CRT_CPP_API HMAC final
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{
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public:
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~HMAC();
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HMAC(const HMAC &) = delete;
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HMAC &operator=(const HMAC &) = delete;
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HMAC(HMAC &&toMove);
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HMAC &operator=(HMAC &&toMove);
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/**
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* Returns true if the instance is in a valid state, false otherwise.
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*/
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inline operator bool() const noexcept { return m_good; }
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/**
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* Returns the value of the last aws error encountered by operations on this instance.
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*/
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inline int LastError() const noexcept { return m_lastError; }
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/**
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* Creates an instance of a Streaming SHA256 HMAC.
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*/
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static HMAC CreateSHA256HMAC(Allocator *allocator, const ByteCursor &secret) noexcept;
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/**
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* Creates an instance of a Streaming SHA256 HMAC using the Default Allocator.
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*/
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static HMAC CreateSHA256HMAC(const ByteCursor &secret) noexcept;
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/**
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* Updates the running HMAC object with data in toHMAC. Returns true on success. Call
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* LastError() for the reason this call failed.
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*/
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bool Update(const ByteCursor &toHMAC) noexcept;
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/**
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* Finishes the running HMAC operation and writes the digest into output. The available capacity of
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* output must be large enough for the digest. See: SHA256_DIGEST_SIZE and MD5_DIGEST_SIZE for size
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* hints. 'truncateTo' is for if you want truncated output (e.g. you only want the first 16 bytes of a
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* SHA256 digest. Returns true on success. Call LastError() for the reason this call failed.
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*/
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bool Digest(ByteBuf &output, size_t truncateTo = 0) noexcept;
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/**
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* Returns the size of the digest for this hmac algorithm. If this object is not valid, it will
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* return 0 instead.
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*/
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size_t DigestSize() const noexcept;
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/**
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* Computes the running HMAC and finishes the running HMAC operation and writes the digest into output.
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* The available capacity of output must be large enough for the digest.
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* See: SHA256_DIGEST_SIZE and MD5_DIGEST_SIZE for size
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* hints. 'truncateTo' is for if you want truncated output (e.g. you only want the first 16 bytes of a
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* SHA256 HMAC digest. Returns true on success. Call LastError() for the reason this call failed.
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*
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* This is an API a user would use for smaller size inputs. For larger, streaming inputs, use
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* multiple calls to Update() for each buffer, followed by a single call to Digest().
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*/
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bool ComputeOneShot(const ByteCursor &input, ByteBuf &output, size_t truncateTo = 0) noexcept;
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private:
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HMAC(aws_hmac *hmac) noexcept;
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HMAC() = delete;
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aws_hmac *m_hmac;
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bool m_good;
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int m_lastError;
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};
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/**
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* BYO_CRYPTO: Base class for custom HMAC implementations.
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*
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* If using BYO_CRYPTO, you must define concrete implementations for the required HMAC algorithms
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* and set their creation callbacks via functions like ApiHandle.SetBYOCryptoNewSHA256HMACCallback().
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*/
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class AWS_CRT_CPP_API ByoHMAC
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{
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public:
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virtual ~ByoHMAC() = default;
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/** @private
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* this is called by the framework. If you're trying to create instances of this class manually,
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* please don't. But if you do. Look at the other factory functions for reference.
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*/
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aws_hmac *SeatForCInterop(const std::shared_ptr<ByoHMAC> &selfRef);
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protected:
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ByoHMAC(size_t digestSize, const ByteCursor &secret, Allocator *allocator = ApiAllocator());
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/**
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* Updates the running HMAC with to_hash.
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* This can be called multiple times.
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* Raise an AWS error and return false to indicate failure.
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*/
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virtual bool UpdateInternal(const ByteCursor &toHash) noexcept = 0;
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/**
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* Complete the HMAC computation and write the final digest to output.
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* This cannote be called more than once.
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* If truncate_to is something other than 0, the output must be truncated to that number of bytes.
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* Raise an AWS error and return false to indicate failure.
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*/
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virtual bool DigestInternal(ByteBuf &output, size_t truncateTo = 0) noexcept = 0;
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private:
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static void s_Destroy(struct aws_hmac *hmac);
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static int s_Update(struct aws_hmac *hmac, const struct aws_byte_cursor *buf);
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static int s_Finalize(struct aws_hmac *hmac, struct aws_byte_buf *out);
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static aws_hmac_vtable s_Vtable;
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aws_hmac m_hmacValue;
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std::shared_ptr<ByoHMAC> m_selfReference;
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};
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using CreateHMACCallback =
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std::function<std::shared_ptr<ByoHMAC>(size_t digestSize, const ByteCursor &secret, Allocator *)>;
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} // namespace Crypto
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} // namespace Crt
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} // namespace Aws
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