/*
This file is part of libmicrohttpd
Copyright (C) 2019-2021 Karlson2k (Evgeny Grin)
libmicrohttpd is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library.
If not, see .
*/
/**
* @file microhttpd/sha256.c
* @brief Calculation of SHA-256 digest as defined in FIPS PUB 180-4 (2015)
* @author Karlson2k (Evgeny Grin)
*/
#include "sha256.h"
#include
#ifdef HAVE_MEMORY_H
#include
#endif /* HAVE_MEMORY_H */
#include "mhd_bithelpers.h"
#include "mhd_assert.h"
/**
* Initialise structure for SHA256 calculation.
*
* @param ctx_ must be a `struct sha256_ctx *`
*/
void
MHD_SHA256_init (void *ctx_)
{
struct sha256_ctx *const ctx = ctx_;
/* Initial hash values, see FIPS PUB 180-4 paragraph 5.3.3 */
/* First thirty-two bits of the fractional parts of the square
* roots of the first eight prime numbers: 2, 3, 5, 7, 11, 13,
* 17, 19." */
ctx->H[0] = UINT32_C (0x6a09e667);
ctx->H[1] = UINT32_C (0xbb67ae85);
ctx->H[2] = UINT32_C (0x3c6ef372);
ctx->H[3] = UINT32_C (0xa54ff53a);
ctx->H[4] = UINT32_C (0x510e527f);
ctx->H[5] = UINT32_C (0x9b05688c);
ctx->H[6] = UINT32_C (0x1f83d9ab);
ctx->H[7] = UINT32_C (0x5be0cd19);
/* Initialise number of bytes. */
ctx->count = 0;
}
/**
* Base of SHA-256 transformation.
* Gets full 64 bytes block of data and updates hash values;
* @param H hash values
* @param data data, must be exactly 64 bytes long
*/
static void
sha256_transform (uint32_t H[_SHA256_DIGEST_LENGTH],
const uint8_t data[SHA256_BLOCK_SIZE])
{
/* Working variables,
see FIPS PUB 180-4 paragraph 6.2. */
uint32_t a = H[0];
uint32_t b = H[1];
uint32_t c = H[2];
uint32_t d = H[3];
uint32_t e = H[4];
uint32_t f = H[5];
uint32_t g = H[6];
uint32_t h = H[7];
/* Data buffer, used as cyclic buffer.
See FIPS PUB 180-4 paragraphs 5.2.1, 6.2. */
uint32_t W[16];
/* 'Ch' and 'Maj' macro functions are defined with
widely-used optimization.
See FIPS PUB 180-4 formulae 4.2, 4.3. */
#define Ch(x,y,z) ( (z) ^ ((x) & ((y) ^ (z))) )
#define Maj(x,y,z) ( ((x) & (y)) ^ ((z) & ((x) ^ (y))) )
/* Unoptimized (original) versions: */
/* #define Ch(x,y,z) ( ( (x) & (y) ) ^ ( ~(x) & (z) ) ) */
/* #define Maj(x,y,z) ( ((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)) ) */
/* Four 'Sigma' macro functions.
See FIPS PUB 180-4 formulae 4.4, 4.5, 4.6, 4.7. */
#define SIG0(x) (_MHD_ROTR32 ((x), 2) ^ _MHD_ROTR32 ((x), 13) ^ \
_MHD_ROTR32 ((x), 22) )
#define SIG1(x) (_MHD_ROTR32 ((x), 6) ^ _MHD_ROTR32 ((x), 11) ^ \
_MHD_ROTR32 ((x), 25) )
#define sig0(x) (_MHD_ROTR32 ((x), 7) ^ _MHD_ROTR32 ((x), 18) ^ \
((x) >> 3) )
#define sig1(x) (_MHD_ROTR32 ((x), 17) ^ _MHD_ROTR32 ((x),19) ^ \
((x) >> 10) )
/* Single step of SHA-256 computation,
see FIPS PUB 180-4 paragraph 6.2.2 step 3.
* Note: instead of reassigning all working variables on each step,
variables are rotated for each step:
SHA2STEP32(a, b, c, d, e, f, g, h, K[0], data[0]);
SHA2STEP32(h, a, b, c, d, e, f, g, K[1], data[1]);
so current 'vD' will be used as 'vE' on next step,
current 'vH' will be used as 'vA' on next step.
* Note: first (vH += SIG1(vE) + Ch(vE,vF,vG) + kt + wt) equals T1 in FIPS PUB 180-4 paragraph 6.2.2 step 3.
second (vH += SIG0(vA) + Maj(vE,vF,vC) equals T1 + T2 in FIPS PUB 180-4 paragraph 6.2.2 step 3.
* Note: 'wt' must be used exactly one time in this macro as it change other data as well
every time when used. */
#define SHA2STEP32(vA,vB,vC,vD,vE,vF,vG,vH,kt,wt) do { \
(vD) += ((vH) += SIG1 ((vE)) + Ch ((vE),(vF),(vG)) + (kt) + (wt)); \
(vH) += SIG0 ((vA)) + Maj ((vA),(vB),(vC)); } while (0)
#ifndef _MHD_GET_32BIT_BE_UNALIGNED
if (0 != (((uintptr_t) data) % _MHD_UINT32_ALIGN))
{
/* Copy the unaligned input data to the aligned buffer */
memcpy (W, data, SHA256_BLOCK_SIZE);
/* The W[] buffer itself will be used as the source of the data,
* but data will be reloaded in correct bytes order during
* the next steps */
data = (uint8_t *) W;
}
#endif /* _MHD_GET_32BIT_BE_UNALIGNED */
/* Get value of W(t) from input data buffer,
See FIPS PUB 180-4 paragraph 6.2.
Input data must be read in big-endian bytes order,
see FIPS PUB 180-4 paragraph 3.1.2. */
/* Use cast to (const void*) to mute compiler alignment warning,
* data was already aligned in previous step */
#define GET_W_FROM_DATA(buf,t) \
_MHD_GET_32BIT_BE ((const void*)(((const uint8_t*) (buf)) + \
(t) * SHA256_BYTES_IN_WORD))
/* During first 16 steps, before making any calculations on each step,
the W element is read from input data buffer as big-endian value and
stored in array of W elements. */
/* Note: instead of using K constants as array, all K values are specified
individually for each step, see FIPS PUB 180-4 paragraph 4.2.2 for K values. */
SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x428a2f98), W[0] = \
GET_W_FROM_DATA (data, 0));
SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x71374491), W[1] = \
GET_W_FROM_DATA (data, 1));
SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xb5c0fbcf), W[2] = \
GET_W_FROM_DATA (data, 2));
SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xe9b5dba5), W[3] = \
GET_W_FROM_DATA (data, 3));
SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x3956c25b), W[4] = \
GET_W_FROM_DATA (data, 4));
SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x59f111f1), W[5] = \
GET_W_FROM_DATA (data, 5));
SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x923f82a4), W[6] = \
GET_W_FROM_DATA (data, 6));
SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xab1c5ed5), W[7] = \
GET_W_FROM_DATA (data, 7));
SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xd807aa98), W[8] = \
GET_W_FROM_DATA (data, 8));
SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x12835b01), W[9] = \
GET_W_FROM_DATA (data, 9));
SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x243185be), W[10] = \
GET_W_FROM_DATA (data, 10));
SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x550c7dc3), W[11] = \
GET_W_FROM_DATA (data, 11));
SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x72be5d74), W[12] = \
GET_W_FROM_DATA (data, 12));
SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x80deb1fe), W[13] = \
GET_W_FROM_DATA (data, 13));
SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x9bdc06a7), W[14] = \
GET_W_FROM_DATA (data, 14));
SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xc19bf174), W[15] = \
GET_W_FROM_DATA (data, 15));
/* 'W' generation and assignment for 16 <= t <= 63.
See FIPS PUB 180-4 paragraph 6.2.2.
As only last 16 'W' are used in calculations, it is possible to
use 16 elements array of W as cyclic buffer.
* Note: ((t-16)&0xf) have same value as (t&0xf) */
#define Wgen(w,t) ( (w)[(t - 16) & 0xf] + sig1 ((w)[((t) - 2) & 0xf]) \
+ (w)[((t) - 7) & 0xf] + sig0 ((w)[((t) - 15) & 0xf]) )
/* During last 48 steps, before making any calculations on each step,
W element is generated from W elements of cyclic buffer and generated value
stored back in cyclic buffer. */
/* Note: instead of using K constants as array, all K values are specified
individually for each step, see FIPS PUB 180-4 paragraph 4.2.2 for K values. */
SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xe49b69c1), W[16 & 0xf] = \
Wgen (W,16));
SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0xefbe4786), W[17 & 0xf] = \
Wgen (W,17));
SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x0fc19dc6), W[18 & 0xf] = \
Wgen (W,18));
SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x240ca1cc), W[19 & 0xf] = \
Wgen (W,19));
SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x2de92c6f), W[20 & 0xf] = \
Wgen (W,20));
SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x4a7484aa), W[21 & 0xf] = \
Wgen (W,21));
SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x5cb0a9dc), W[22 & 0xf] = \
Wgen (W,22));
SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x76f988da), W[23 & 0xf] = \
Wgen (W,23));
SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x983e5152), W[24 & 0xf] = \
Wgen (W,24));
SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0xa831c66d), W[25 & 0xf] = \
Wgen (W,25));
SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xb00327c8), W[26 & 0xf] = \
Wgen (W,26));
SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xbf597fc7), W[27 & 0xf] = \
Wgen (W,27));
SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0xc6e00bf3), W[28 & 0xf] = \
Wgen (W,28));
SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0xd5a79147), W[29 & 0xf] = \
Wgen (W,29));
SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x06ca6351), W[30 & 0xf] = \
Wgen (W,30));
SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x14292967), W[31 & 0xf] = \
Wgen (W,31));
SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x27b70a85), W[32 & 0xf] = \
Wgen (W,32));
SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x2e1b2138), W[33 & 0xf] = \
Wgen (W,33));
SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x4d2c6dfc), W[34 & 0xf] = \
Wgen (W,34));
SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x53380d13), W[35 & 0xf] = \
Wgen (W,35));
SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x650a7354), W[36 & 0xf] = \
Wgen (W,36));
SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x766a0abb), W[37 & 0xf] = \
Wgen (W,37));
SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x81c2c92e), W[38 & 0xf] = \
Wgen (W,38));
SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x92722c85), W[39 & 0xf] = \
Wgen (W,39));
SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0xa2bfe8a1), W[40 & 0xf] = \
Wgen (W,40));
SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0xa81a664b), W[41 & 0xf] = \
Wgen (W,41));
SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0xc24b8b70), W[42 & 0xf] = \
Wgen (W,42));
SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0xc76c51a3), W[43 & 0xf] = \
Wgen (W,43));
SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0xd192e819), W[44 & 0xf] = \
Wgen (W,44));
SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0xd6990624), W[45 & 0xf] = \
Wgen (W,45));
SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0xf40e3585), W[46 & 0xf] = \
Wgen (W,46));
SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x106aa070), W[47 & 0xf] = \
Wgen (W,47));
SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x19a4c116), W[48 & 0xf] = \
Wgen (W,48));
SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x1e376c08), W[49 & 0xf] = \
Wgen (W,49));
SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x2748774c), W[50 & 0xf] = \
Wgen (W,50));
SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x34b0bcb5), W[51 & 0xf] = \
Wgen (W,51));
SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x391c0cb3), W[52 & 0xf] = \
Wgen (W,52));
SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0x4ed8aa4a), W[53 & 0xf] = \
Wgen (W,53));
SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0x5b9cca4f), W[54 & 0xf] = \
Wgen (W,54));
SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0x682e6ff3), W[55 & 0xf] = \
Wgen (W,55));
SHA2STEP32 (a, b, c, d, e, f, g, h, UINT32_C (0x748f82ee), W[56 & 0xf] = \
Wgen (W,56));
SHA2STEP32 (h, a, b, c, d, e, f, g, UINT32_C (0x78a5636f), W[57 & 0xf] = \
Wgen (W,57));
SHA2STEP32 (g, h, a, b, c, d, e, f, UINT32_C (0x84c87814), W[58 & 0xf] = \
Wgen (W,58));
SHA2STEP32 (f, g, h, a, b, c, d, e, UINT32_C (0x8cc70208), W[59 & 0xf] = \
Wgen (W,59));
SHA2STEP32 (e, f, g, h, a, b, c, d, UINT32_C (0x90befffa), W[60 & 0xf] = \
Wgen (W,60));
SHA2STEP32 (d, e, f, g, h, a, b, c, UINT32_C (0xa4506ceb), W[61 & 0xf] = \
Wgen (W,61));
SHA2STEP32 (c, d, e, f, g, h, a, b, UINT32_C (0xbef9a3f7), W[62 & 0xf] = \
Wgen (W,62));
SHA2STEP32 (b, c, d, e, f, g, h, a, UINT32_C (0xc67178f2), W[63 & 0xf] = \
Wgen (W,63));
/* Compute intermediate hash.
See FIPS PUB 180-4 paragraph 6.2.2 step 4. */
H[0] += a;
H[1] += b;
H[2] += c;
H[3] += d;
H[4] += e;
H[5] += f;
H[6] += g;
H[7] += h;
}
/**
* Process portion of bytes.
*
* @param ctx_ must be a `struct sha256_ctx *`
* @param data bytes to add to hash
* @param length number of bytes in @a data
*/
void
MHD_SHA256_update (void *ctx_,
const uint8_t *data,
size_t length)
{
struct sha256_ctx *const ctx = ctx_;
unsigned bytes_have; /**< Number of bytes in buffer */
mhd_assert ((data != NULL) || (length == 0));
if (0 == length)
return; /* Do nothing */
/* Note: (count & (SHA256_BLOCK_SIZE-1))
equals (count % SHA256_BLOCK_SIZE) for this block size. */
bytes_have = (unsigned) (ctx->count & (SHA256_BLOCK_SIZE - 1));
ctx->count += length;
if (0 != bytes_have)
{
unsigned bytes_left = SHA256_BLOCK_SIZE - bytes_have;
if (length >= bytes_left)
{ /* Combine new data with data in the buffer and
process full block. */
memcpy (ctx->buffer + bytes_have,
data,
bytes_left);
data += bytes_left;
length -= bytes_left;
sha256_transform (ctx->H, ctx->buffer);
bytes_have = 0;
}
}
while (SHA256_BLOCK_SIZE <= length)
{ /* Process any full blocks of new data directly,
without copying to the buffer. */
sha256_transform (ctx->H, data);
data += SHA256_BLOCK_SIZE;
length -= SHA256_BLOCK_SIZE;
}
if (0 != length)
{ /* Copy incomplete block of new data (if any)
to the buffer. */
memcpy (ctx->buffer + bytes_have, data, length);
}
}
/**
* Size of "length" padding addition in bytes.
* See FIPS PUB 180-4 paragraph 5.1.1.
*/
#define SHA256_SIZE_OF_LEN_ADD (64 / 8)
/**
* Finalise SHA256 calculation, return digest.
*
* @param ctx_ must be a `struct sha256_ctx *`
* @param[out] digest set to the hash, must be #SHA256_DIGEST_SIZE bytes
*/
void
MHD_SHA256_finish (void *ctx_,
uint8_t digest[SHA256_DIGEST_SIZE])
{
struct sha256_ctx *const ctx = ctx_;
uint64_t num_bits; /**< Number of processed bits */
unsigned bytes_have; /**< Number of bytes in buffer */
num_bits = ctx->count << 3;
/* Note: (count & (SHA256_BLOCK_SIZE-1))
equal (count % SHA256_BLOCK_SIZE) for this block size. */
bytes_have = (unsigned) (ctx->count & (SHA256_BLOCK_SIZE - 1));
/* Input data must be padded with bit "1" and with length of data in bits.
See FIPS PUB 180-4 paragraph 5.1.1. */
/* Data is always processed in form of bytes (not by individual bits),
therefore position of first padding bit in byte is always predefined (0x80). */
/* Buffer always have space at least for one byte (as full buffers are
processed immediately). */
ctx->buffer[bytes_have++] = 0x80;
if (SHA256_BLOCK_SIZE - bytes_have < SHA256_SIZE_OF_LEN_ADD)
{ /* No space in current block to put total length of message.
Pad current block with zeros and process it. */
if (bytes_have < SHA256_BLOCK_SIZE)
memset (ctx->buffer + bytes_have, 0, SHA256_BLOCK_SIZE - bytes_have);
/* Process full block. */
sha256_transform (ctx->H, ctx->buffer);
/* Start new block. */
bytes_have = 0;
}
/* Pad the rest of the buffer with zeros. */
memset (ctx->buffer + bytes_have, 0,
SHA256_BLOCK_SIZE - SHA256_SIZE_OF_LEN_ADD - bytes_have);
/* Put number of bits in processed message as big-endian value. */
_MHD_PUT_64BIT_BE_SAFE (ctx->buffer + SHA256_BLOCK_SIZE
- SHA256_SIZE_OF_LEN_ADD,
num_bits);
/* Process full final block. */
sha256_transform (ctx->H, ctx->buffer);
/* Put final hash/digest in BE mode */
#ifndef _MHD_PUT_32BIT_BE_UNALIGNED
if (0 != ((uintptr_t) digest) % _MHD_UINT32_ALIGN)
{
uint32_t alig_dgst[_SHA256_DIGEST_LENGTH];
_MHD_PUT_32BIT_BE (alig_dgst + 0, ctx->H[0]);
_MHD_PUT_32BIT_BE (alig_dgst + 1, ctx->H[1]);
_MHD_PUT_32BIT_BE (alig_dgst + 2, ctx->H[2]);
_MHD_PUT_32BIT_BE (alig_dgst + 3, ctx->H[3]);
_MHD_PUT_32BIT_BE (alig_dgst + 4, ctx->H[4]);
_MHD_PUT_32BIT_BE (alig_dgst + 5, ctx->H[5]);
_MHD_PUT_32BIT_BE (alig_dgst + 6, ctx->H[6]);
_MHD_PUT_32BIT_BE (alig_dgst + 7, ctx->H[7]);
/* Copy result to unaligned destination address */
memcpy (digest, alig_dgst, SHA256_DIGEST_SIZE);
}
else
#else /* _MHD_PUT_32BIT_BE_UNALIGNED */
if (1)
#endif /* _MHD_PUT_32BIT_BE_UNALIGNED */
{
/* Use cast to (void*) here to mute compiler alignment warnings.
* Compilers are not smart enough to see that alignment has been checked. */
_MHD_PUT_32BIT_BE ((void *) (digest + 0 * SHA256_BYTES_IN_WORD), ctx->H[0]);
_MHD_PUT_32BIT_BE ((void *) (digest + 1 * SHA256_BYTES_IN_WORD), ctx->H[1]);
_MHD_PUT_32BIT_BE ((void *) (digest + 2 * SHA256_BYTES_IN_WORD), ctx->H[2]);
_MHD_PUT_32BIT_BE ((void *) (digest + 3 * SHA256_BYTES_IN_WORD), ctx->H[3]);
_MHD_PUT_32BIT_BE ((void *) (digest + 4 * SHA256_BYTES_IN_WORD), ctx->H[4]);
_MHD_PUT_32BIT_BE ((void *) (digest + 5 * SHA256_BYTES_IN_WORD), ctx->H[5]);
_MHD_PUT_32BIT_BE ((void *) (digest + 6 * SHA256_BYTES_IN_WORD), ctx->H[6]);
_MHD_PUT_32BIT_BE ((void *) (digest + 7 * SHA256_BYTES_IN_WORD), ctx->H[7]);
}
/* Erase potentially sensitive data. */
memset (ctx, 0, sizeof(struct sha256_ctx));
}