mirror of
https://github.com/RGBCube/serenity
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122 lines
3.6 KiB
C++
122 lines
3.6 KiB
C++
/*
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* Copyright (c) 2020, Ali Mohammad Pur <mpfard@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/ByteBuffer.h>
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#include <AK/StringBuilder.h>
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#include <AK/StringView.h>
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#include <AK/Types.h>
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#include <AK/Vector.h>
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#ifndef KERNEL
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# include <AK/DeprecatedString.h>
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#endif
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constexpr static auto IPAD = 0x36;
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constexpr static auto OPAD = 0x5c;
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namespace Crypto::Authentication {
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template<typename HashT>
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class HMAC {
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public:
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using HashType = HashT;
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using TagType = typename HashType::DigestType;
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constexpr size_t digest_size() const { return m_inner_hasher.digest_size(); }
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template<typename KeyBufferType, typename... Args>
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HMAC(KeyBufferType key, Args... args)
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: m_inner_hasher(args...)
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, m_outer_hasher(args...)
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{
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derive_key(key);
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reset();
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}
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TagType process(u8 const* message, size_t length)
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{
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reset();
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update(message, length);
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return digest();
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}
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void update(u8 const* message, size_t length)
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{
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m_inner_hasher.update(message, length);
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}
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TagType process(ReadonlyBytes span) { return process(span.data(), span.size()); }
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TagType process(StringView string) { return process((u8 const*)string.characters_without_null_termination(), string.length()); }
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void update(ReadonlyBytes span) { return update(span.data(), span.size()); }
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void update(StringView string) { return update((u8 const*)string.characters_without_null_termination(), string.length()); }
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TagType digest()
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{
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m_outer_hasher.update(m_inner_hasher.digest().immutable_data(), m_inner_hasher.digest_size());
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auto result = m_outer_hasher.digest();
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reset();
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return result;
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}
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void reset()
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{
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m_inner_hasher.reset();
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m_outer_hasher.reset();
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m_inner_hasher.update(m_key_data, m_inner_hasher.block_size());
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m_outer_hasher.update(m_key_data + m_inner_hasher.block_size(), m_outer_hasher.block_size());
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}
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#ifndef KERNEL
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DeprecatedString class_name() const
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{
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StringBuilder builder;
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builder.append("HMAC-"sv);
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builder.append(m_inner_hasher.class_name());
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return builder.to_deprecated_string();
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}
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#endif
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private:
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void derive_key(u8 const* key, size_t length)
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{
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auto block_size = m_inner_hasher.block_size();
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// Note: The block size of all the current hash functions is 512 bits.
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Vector<u8, 64> v_key;
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v_key.resize(block_size);
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auto key_buffer = v_key.span();
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// m_key_data is zero'd, so copying the data in
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// the first few bytes leaves the rest zero, which
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// is exactly what we want (zero padding)
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if (length > block_size) {
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m_inner_hasher.update(key, length);
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auto digest = m_inner_hasher.digest();
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// FIXME: should we check if the hash function creates more data than its block size?
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key_buffer.overwrite(0, digest.immutable_data(), m_inner_hasher.digest_size());
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} else {
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key_buffer.overwrite(0, key, length);
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}
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// fill out the inner and outer padded keys
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auto* i_key = m_key_data;
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auto* o_key = m_key_data + block_size;
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for (size_t i = 0; i < block_size; ++i) {
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auto key_byte = key_buffer[i];
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i_key[i] = key_byte ^ IPAD;
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o_key[i] = key_byte ^ OPAD;
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}
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}
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void derive_key(ReadonlyBytes key) { derive_key(key.data(), key.size()); }
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void derive_key(StringView key) { derive_key(key.bytes()); }
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HashType m_inner_hasher, m_outer_hasher;
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u8 m_key_data[2048];
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};
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}
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