285 lines
10 KiB
C++
285 lines
10 KiB
C++
// Derived from the "RSA Data Security, Inc. MD5 Message-Digest Algorithm":
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// src: https://github.com/freebsd/freebsd-src/blob/release/14.2.0/sys/kern/md5c.c
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#include <bit>
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#include <cstdint>
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#include <cstring>
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#include "md5.h"
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#if defined(_MSC_VER)
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#define bswap_u16 _byteswap_ushort
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#define bswap_u32 _byteswap_ulong
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#define bswap_u64 _byteswap_uint64
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#else
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#define bswap_u16 __builtin_bswap16
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#define bswap_u32 __builtin_bswap32
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#define bswap_u64 __builtin_bswap64
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#endif
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template <typename T>
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void Encode(uint8_t* output, const T input)
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requires(std::is_integral_v<T> && (sizeof(T) == 1 || sizeof(T) == 2 || sizeof(T) == 4 || sizeof(T) == 8))
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{
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if constexpr (std::endian::native == std::endian::little || sizeof(T) == 1) {
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memcpy(output, &input, sizeof(T));
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// ReSharper disable once CppDFAUnreachableCode
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} else if constexpr (sizeof(T) == 2) {
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*reinterpret_cast<uint16_t*>(output) = bswap_u16(input);
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} else if constexpr (sizeof(T) == 4) {
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*reinterpret_cast<uint32_t*>(output) = bswap_u32(input);
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} else if constexpr (sizeof(T) == 8) {
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*reinterpret_cast<uint64_t*>(output) = bswap_u64(input);
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}
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}
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template <typename T>
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void Decode(T* output, const uint8_t* input)
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requires(std::is_integral_v<T> && (sizeof(T) == 1 || sizeof(T) == 2 || sizeof(T) == 4 || sizeof(T) == 8))
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{
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if constexpr (std::endian::native == std::endian::little) {
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memcpy(output, input, sizeof(T));
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// ReSharper disable once CppDFAUnreachableCode
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} else if constexpr (sizeof(T) == 2) {
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*output = bswap_u16(*reinterpret_cast<const uint16_t*>(input));
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} else if constexpr (sizeof(T) == 4) {
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*output = bswap_u32(*reinterpret_cast<const uint32_t*>(input));
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} else if constexpr (sizeof(T) == 8) {
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*output = bswap_u64(*reinterpret_cast<const uint64_t*>(input));
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}
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}
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inline void Encode(unsigned char* output, const uint32_t* input, const unsigned int len) {
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if constexpr (std::endian::native == std::endian::little) {
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memcpy(output, input, len);
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} else {
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// ReSharper disable once CppDFAUnreachableCode
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for (unsigned int i = 0; i < len; i += 4, output += 4) {
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Encode(output, input[i]);
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}
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}
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}
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inline void Decode(uint32_t* output, const unsigned char* input, const unsigned int len) {
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// ReSharper disable once CppDFAUnreachableCode
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if constexpr (std::endian::native == std::endian::little) {
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memcpy(output, input, len);
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} else {
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for (unsigned int i = 0; i < len; i += 4, ++output) {
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Decode(output, &input[i]);
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}
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}
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}
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void MD5Transform(uint32_t state[4], const unsigned char block[64]);
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static unsigned char PADDING[64] = {0x80};
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/* F, G, H and I are basic MD5 functions. */
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#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
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#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
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#define H(x, y, z) ((x) ^ (y) ^ (z))
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#define I(x, y, z) ((y) ^ ((x) | (~z)))
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/* ROTATE_LEFT rotates x left n bits. */
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#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n))))
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/*
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* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
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* Rotation is separate from addition to prevent recomputation.
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*/
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#define FF(a, b, c, d, x, s, ac) \
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{ \
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(a) += F((b), (c), (d)) + (x) + (uint32_t)(ac); \
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(a) = ROTATE_LEFT((a), (s)); \
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(a) += (b); \
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}
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#define GG(a, b, c, d, x, s, ac) \
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{ \
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(a) += G((b), (c), (d)) + (x) + (uint32_t)(ac); \
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(a) = ROTATE_LEFT((a), (s)); \
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(a) += (b); \
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}
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#define HH(a, b, c, d, x, s, ac) \
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{ \
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(a) += H((b), (c), (d)) + (x) + (uint32_t)(ac); \
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(a) = ROTATE_LEFT((a), (s)); \
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(a) += (b); \
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}
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#define II(a, b, c, d, x, s, ac) \
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{ \
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(a) += I((b), (c), (d)) + (x) + (uint32_t)(ac); \
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(a) = ROTATE_LEFT((a), (s)); \
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(a) += (b); \
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}
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/*
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* MD5 block update operation. Continues an MD5 message-digest
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* operation, processing another message block, and updating the
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* context.
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*/
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void md5_update(MD5_CTX* ctx, const uint8_t* in, const size_t len) {
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unsigned int i{0};
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const unsigned char* input = in;
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/* Compute number of bytes mod 64 */
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unsigned int index = ctx->count % 64;
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ctx->count += len;
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// ReSharper disable once CppTooWideScopeInitStatement
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const unsigned int partLen = 64 - index;
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/* Transform as many times as possible. */
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if (len >= partLen) {
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memcpy(&ctx->buffer[index], input, partLen);
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MD5Transform(ctx->state, ctx->buffer);
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for (i = partLen; i + 63 < len; i += 64) {
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MD5Transform(ctx->state, &input[i]);
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}
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index = 0;
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}
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/* Buffer remaining input */
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memcpy(&ctx->buffer[index], &input[i], len - i);
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}
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/*
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* MD5 padding. Adds padding followed by original length.
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*/
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static void MD5Pad(MD5_CTX* context) {
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unsigned char bits[8];
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/* Save number of bits */
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Encode(bits, context->count << 3);
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/* Pad out to 56 mod 64. */
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const unsigned int index = context->count % 64;
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const unsigned int padLen = index < 56 ? 56 - index : 120 - index;
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md5_update(context, PADDING, padLen);
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/* Append length (before padding) */
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md5_update(context, bits, 8);
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}
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/*
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* MD5 finalization. Ends an MD5 message-digest operation, writing
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* the message digest and zeroizing the context.
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*/
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void md5_final(MD5_CTX* ctx, uint8_t* digest) {
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/* Do padding. */
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MD5Pad(ctx);
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/* Store state in digest */
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Encode(digest, ctx->state, MD5_DIGEST_LENGTH);
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/* Zeroize sensitive information. */
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memset(ctx, 0, sizeof(*ctx));
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}
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/* MD5 basic transformation. Transforms state based on block. */
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void MD5Transform(uint32_t state[4], const unsigned char block[64]) {
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uint32_t a = state[0], b = state[1], c = state[2], d = state[3], x[16];
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Decode(x, block, 64);
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/* Round 1 */
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constexpr int S11 = 7;
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constexpr int S12 = 12;
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constexpr int S13 = 17;
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constexpr int S14 = 22;
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FF(a, b, c, d, x[0], S11, 0xd76aa478); /* 1 */
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FF(d, a, b, c, x[1], S12, 0xe8c7b756); /* 2 */
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FF(c, d, a, b, x[2], S13, 0x242070db); /* 3 */
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FF(b, c, d, a, x[3], S14, 0xc1bdceee); /* 4 */
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FF(a, b, c, d, x[4], S11, 0xf57c0faf); /* 5 */
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FF(d, a, b, c, x[5], S12, 0x4787c62a); /* 6 */
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FF(c, d, a, b, x[6], S13, 0xa8304613); /* 7 */
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FF(b, c, d, a, x[7], S14, 0xfd469501); /* 8 */
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FF(a, b, c, d, x[8], S11, 0x698098d8); /* 9 */
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FF(d, a, b, c, x[9], S12, 0x8b44f7af); /* 10 */
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FF(c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
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FF(b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
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FF(a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
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FF(d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
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FF(c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
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FF(b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
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/* Round 2 */
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constexpr int S21 = 5;
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constexpr int S22 = 9;
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constexpr int S23 = 14;
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constexpr int S24 = 20;
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GG(a, b, c, d, x[1], S21, 0xf61e2562); /* 17 */
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GG(d, a, b, c, x[6], S22, 0xc040b340); /* 18 */
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GG(c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
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GG(b, c, d, a, x[0], S24, 0xe9b6c7aa); /* 20 */
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GG(a, b, c, d, x[5], S21, 0xd62f105d); /* 21 */
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GG(d, a, b, c, x[10], S22, 0x2441453); /* 22 */
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GG(c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
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GG(b, c, d, a, x[4], S24, 0xe7d3fbc8); /* 24 */
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GG(a, b, c, d, x[9], S21, 0x21e1cde6); /* 25 */
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GG(d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
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GG(c, d, a, b, x[3], S23, 0xf4d50d87); /* 27 */
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GG(b, c, d, a, x[8], S24, 0x455a14ed); /* 28 */
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GG(a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
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GG(d, a, b, c, x[2], S22, 0xfcefa3f8); /* 30 */
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GG(c, d, a, b, x[7], S23, 0x676f02d9); /* 31 */
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GG(b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
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/* Round 3 */
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constexpr int S31 = 4;
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constexpr int S32 = 11;
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constexpr int S33 = 16;
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constexpr int S34 = 23;
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HH(a, b, c, d, x[5], S31, 0xfffa3942); /* 33 */
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HH(d, a, b, c, x[8], S32, 0x8771f681); /* 34 */
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HH(c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
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HH(b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
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HH(a, b, c, d, x[1], S31, 0xa4beea44); /* 37 */
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HH(d, a, b, c, x[4], S32, 0x4bdecfa9); /* 38 */
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HH(c, d, a, b, x[7], S33, 0xf6bb4b60); /* 39 */
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HH(b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
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HH(a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
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HH(d, a, b, c, x[0], S32, 0xeaa127fa); /* 42 */
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HH(c, d, a, b, x[3], S33, 0xd4ef3085); /* 43 */
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HH(b, c, d, a, x[6], S34, 0x4881d05); /* 44 */
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HH(a, b, c, d, x[9], S31, 0xd9d4d039); /* 45 */
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HH(d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
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HH(c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
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HH(b, c, d, a, x[2], S34, 0xc4ac5665); /* 48 */
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/* Round 4 */
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constexpr int S41 = 6;
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constexpr int S42 = 10;
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constexpr int S43 = 15;
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constexpr int S44 = 21;
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II(a, b, c, d, x[0], S41, 0xf4292244); /* 49 */
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II(d, a, b, c, x[7], S42, 0x432aff97); /* 50 */
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II(c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
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II(b, c, d, a, x[5], S44, 0xfc93a039); /* 52 */
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II(a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
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II(d, a, b, c, x[3], S42, 0x8f0ccc92); /* 54 */
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II(c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
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II(b, c, d, a, x[1], S44, 0x85845dd1); /* 56 */
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II(a, b, c, d, x[8], S41, 0x6fa87e4f); /* 57 */
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II(d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
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II(c, d, a, b, x[6], S43, 0xa3014314); /* 59 */
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II(b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
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II(a, b, c, d, x[4], S41, 0xf7537e82); /* 61 */
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II(d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
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II(c, d, a, b, x[2], S43, 0x2ad7d2bb); /* 63 */
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II(b, c, d, a, x[9], S44, 0xeb86d391); /* 64 */
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state[0] += a;
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state[1] += b;
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state[2] += c;
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state[3] += d;
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/* Zeroize sensitive information. */
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memset(x, 0, sizeof(x));
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}
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