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// Copyright 1999-2016 The OpenSSL Project Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef OPENSSL_HEADER_CRYPTO_FIPSMODULE_DIGEST_MD32_COMMON_H
#define OPENSSL_HEADER_CRYPTO_FIPSMODULE_DIGEST_MD32_COMMON_H
#include <openssl/base.h>
#include <openssl/span.h>
#include <assert.h>
#include "../../internal.h"
BSSL_NAMESPACE_BEGIN
// This is a generic 32-bit "collector" for message digest algorithms. It
// collects input character stream into chunks of 32-bit values and invokes the
// block function that performs the actual hash calculations.
//
// To make use of this mechanism, the hash context should be defined with the
// following parameters.
//
// typedef struct <name>_state_st {
// uint32_t h[<chaining length> / sizeof(uint32_t)];
// uint32_t Nl, Nh;
// uint8_t data[<block size>];
// unsigned num;
// ...
// } <NAME>_CTX;
//
// <chaining length> is the output length of the hash in bytes, before
// any truncation (e.g. 64 for SHA-224 and SHA-256, 128 for SHA-384 and
// SHA-512).
//
// |h| is the hash state and is updated by a function of type
// |crypto_md32_block_func|. |data| is the partial unprocessed block and has
// |num| bytes. |Nl| and |Nh| maintain the number of bits processed so far.
//
// The template parameter is then a traits struct defined as follows:
//
// struct HashTraits {
// // HashContext is the hash type defined above.
// using HashContext = <NAME>_CTX;
//
// // kBlockSize is the block size of the hash function.
// static constexpr size_t kBlockSize = <block size>;
//
// // kLengthIsBigEndian determines whether the final length is encoded in
// // big or little endian.
// static constexpr bool kLengthIsBigEndian = ...;
//
// // HashBlocks incorporates |num_blocks| blocks of input from |data|
// // into |state|. It is assumed the caller has sized |state| and |data|
// // for the hash function.
// static void HashBlocks(uint32_t *state, const uint8_t *data,
// size_t num_blocks) {
// <name>_block_data_order(state, data, num_blocks);
// }
// };
//
// The reason for this formulation is to encourage the compiler to specialize
// all the code for the block size and block function.
// crypto_md32_update hashes |in| to |ctx|.
template <typename Traits>
inline void crypto_md32_update(typename Traits::HashContext *ctx,
Span<const uint8_t> in) {
static_assert(Traits::kBlockSize == sizeof(ctx->data), "block size is wrong");
if (in.empty()) {
return;
}
uint32_t l = ctx->Nl + ((static_cast<uint32_t>(in.size())) << 3);
if (l < ctx->Nl) {
// Handle carries.
ctx->Nh++;
}
ctx->Nh += static_cast<uint32_t>(in.size() >> 29);
ctx->Nl = l;
size_t n = ctx->num;
if (n != 0) {
if (in.size() >= Traits::kBlockSize ||
in.size() + n >= Traits::kBlockSize) {
OPENSSL_memcpy(ctx->data + n, in.data(), Traits::kBlockSize - n);
Traits::HashBlocks(ctx->h, ctx->data, 1);
in = in.subspan(Traits::kBlockSize - n);
ctx->num = 0;
// Keep |data| zeroed when unused.
OPENSSL_memset(ctx->data, 0, Traits::kBlockSize);
} else {
OPENSSL_memcpy(ctx->data + n, in.data(), in.size());
ctx->num += static_cast<unsigned>(in.size());
return;
}
}
n = in.size() / Traits::kBlockSize;
if (n > 0) {
Traits::HashBlocks(ctx->h, in.data(), n);
in = in.subspan(n * Traits::kBlockSize);
}
if (!in.empty()) {
ctx->num = static_cast<unsigned>(in.size());
OPENSSL_memcpy(ctx->data, in.data(), in.size());
}
}
// crypto_md32_final incorporates the partial block and trailing length into the
// digest state in |ctx|. The trailing length is encoded in little-endian if
// |is_big_endian| is zero and big-endian otherwise. |data| must be a buffer of
// length |block_size| with the first |*num| bytes containing a partial block.
// |Nh| and |Nl| contain the total number of bits processed. On return, this
// function clears the partial block in |data| and
// |*num|.
//
// This function does not serialize |h| into a final digest. This is the
// responsibility of the caller.
template <typename Traits>
inline void crypto_md32_final(typename Traits::HashContext *ctx) {
static_assert(Traits::kBlockSize == sizeof(ctx->data), "block size is wrong");
// |data| always has room for at least one byte. A full block would have
// been consumed.
size_t n = ctx->num;
assert(n < Traits::kBlockSize);
ctx->data[n] = 0x80;
n++;
// Fill the block with zeros if there isn't room for a 64-bit length.
if (n > Traits::kBlockSize - 8) {
OPENSSL_memset(ctx->data + n, 0, Traits::kBlockSize - n);
n = 0;
Traits::HashBlocks(ctx->h, ctx->data, 1);
}
OPENSSL_memset(ctx->data + n, 0, Traits::kBlockSize - 8 - n);
// Append a 64-bit length to the block and process it.
if constexpr (Traits::kLengthIsBigEndian) {
CRYPTO_store_u32_be(ctx->data + Traits::kBlockSize - 8, ctx->Nh);
CRYPTO_store_u32_be(ctx->data + Traits::kBlockSize - 4, ctx->Nl);
} else {
CRYPTO_store_u32_le(ctx->data + Traits::kBlockSize - 8, ctx->Nl);
CRYPTO_store_u32_le(ctx->data + Traits::kBlockSize - 4, ctx->Nh);
}
Traits::HashBlocks(ctx->h, ctx->data, 1);
ctx->num = 0;
OPENSSL_memset(ctx->data, 0, Traits::kBlockSize);
}
BSSL_NAMESPACE_END
#endif // OPENSSL_HEADER_CRYPTO_FIPSMODULE_DIGEST_MD32_COMMON_H