Atmosphere/stratosphere/spl/source/spl_ctr_drbg.cpp

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/*
* Copyright (c) 2018-2020 Atmosphère-NX
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*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stratosphere.hpp>
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#include "spl_ctr_drbg.hpp"
namespace ams::spl {
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void CtrDrbg::Update(const void *data) {
aes128ContextCreate(&this->aes_ctx, this->key, true);
for (size_t offset = 0; offset < sizeof(this->work[1]); offset += BlockSize) {
IncrementCounter(this->counter);
aes128EncryptBlock(&this->aes_ctx, &this->work[1][offset], this->counter);
}
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Xor(this->work[1], data, sizeof(this->work[1]));
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std::memcpy(this->key, &this->work[1][0], sizeof(this->key));
std::memcpy(this->counter, &this->work[1][BlockSize], sizeof(this->key));
}
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void CtrDrbg::Initialize(const void *seed) {
std::memcpy(this->work[0], seed, sizeof(this->work[0]));
std::memset(this->key, 0, sizeof(this->key));
std::memset(this->counter, 0, sizeof(this->counter));
this->Update(this->work[0]);
this->reseed_counter = 1;
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}
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void CtrDrbg::Reseed(const void *seed) {
std::memcpy(this->work[0], seed, sizeof(this->work[0]));
this->Update(this->work[0]);
this->reseed_counter = 1;
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}
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bool CtrDrbg::GenerateRandomBytes(void *out, size_t size) {
if (size > MaxRequestSize) {
return false;
}
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if (this->reseed_counter > ReseedInterval) {
return false;
}
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aes128ContextCreate(&this->aes_ctx, this->key, true);
u8 *cur_dst = reinterpret_cast<u8 *>(out);
size_t aligned_size = (size & ~(BlockSize - 1));
for (size_t offset = 0; offset < aligned_size; offset += BlockSize) {
IncrementCounter(this->counter);
aes128EncryptBlock(&this->aes_ctx, cur_dst, this->counter);
cur_dst += BlockSize;
}
if (size > aligned_size) {
IncrementCounter(this->counter);
aes128EncryptBlock(&this->aes_ctx, this->work[1], this->counter);
std::memcpy(cur_dst, this->work[1], size - aligned_size);
}
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std::memset(this->work[0], 0, sizeof(this->work[0]));
this->Update(this->work[0]);
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this->reseed_counter++;
return true;
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}
}