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89061dd3c4
This required multiple changes: - Make hashes non-copiable because they contain a heap allocated pointer - Reference classes via `NonnullOwnPtr` only (they are non-copiable) - Drop all existing hashes implementations - Use the `OpenSSLHashFunction` base class to implement the same hashes I was not able to come up with a way to divide this commit into multiple without increasing the amount of changes. Nothing breaks with this commit!
57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
/*
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* Copyright (c) 2024, stelar7 <dudedbz@gmail.com>
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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/ByteReader.h>
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#include <AK/Endian.h>
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namespace Crypto::Hash {
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class MGF {
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public:
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// https://datatracker.ietf.org/doc/html/rfc2437#section-10.2.1
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template<typename HashFunction>
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static ErrorOr<ByteBuffer> mgf1(ReadonlyBytes seed, size_t length)
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requires requires { HashFunction::digest_size(); }
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{
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auto hash = HashFunction::create();
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size_t h_len = hash->digest_size();
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// 1. If length > 2^32(hLen), output "mask too long" and stop.
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if constexpr (sizeof(size_t) > 32) {
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if (length > (h_len << 32))
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return Error::from_string_literal("mask too long");
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}
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// 2. Let T be the empty octet string.
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auto t = TRY(ByteBuffer::create_uninitialized(0));
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// 3. For counter from 0 to ceil(length / hLen) - 1, do the following:
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auto counter = 0u;
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auto iterations = AK::ceil_div(length, h_len) - 1;
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auto c = TRY(ByteBuffer::create_uninitialized(4));
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for (; counter <= iterations; ++counter) {
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// a. Convert counter to an octet string C of length 4 with the primitive I2OSP: C = I2OSP(counter, 4)
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ByteReader::store(static_cast<u8*>(c.data()), AK::convert_between_host_and_big_endian(static_cast<u32>(counter)));
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// b. Concatenate the hash of the seed Z and C to the octet string T: T = T || Hash (Z || C)
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hash->update(seed);
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hash->update(c);
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auto digest = hash->digest();
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TRY(t.try_append(digest.bytes()));
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}
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// 4. Output the leading l octets of T as the octet string mask.
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return t.slice(0, length);
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}
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};
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}
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