#include <stdint.h> /* Process LEN bytes of BUFFER, accumulating context into CTX. It is assumed that LEN % 64 == 0. */ void __sha256_process_block (const void *buffer, size_t len, struct sha256_ctx *ctx) { const uint32_t *words = buffer; size_t nwords = len / sizeof (uint32_t); uint32_t a = ctx->H[0]; uint32_t b = ctx->H[1]; uint32_t c = ctx->H[2]; uint32_t d = ctx->H[3]; uint32_t e = ctx->H[4]; uint32_t f = ctx->H[5]; uint32_t g = ctx->H[6]; uint32_t h = ctx->H[7]; /* First increment the byte count. FIPS 180-2 specifies the possible length of the file up to 2^64 bits. Here we only compute the number of bytes. */ ctx->total64 += len; /* Process all bytes in the buffer with 64 bytes in each round of the loop. */ while (nwords > 0) { uint32_t W[64]; uint32_t a_save = a; uint32_t b_save = b; uint32_t c_save = c; uint32_t d_save = d; uint32_t e_save = e; uint32_t f_save = f; uint32_t g_save = g; uint32_t h_save = h; /* Operators defined in FIPS 180-2:4.1.2. */ #define Ch(x, y, z) ((x & y) ^ (~x & z)) #define Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z)) #define S0(x) (CYCLIC (x, 2) ^ CYCLIC (x, 13) ^ CYCLIC (x, 22)) #define S1(x) (CYCLIC (x, 6) ^ CYCLIC (x, 11) ^ CYCLIC (x, 25)) #define R0(x) (CYCLIC (x, 7) ^ CYCLIC (x, 18) ^ (x >> 3)) #define R1(x) (CYCLIC (x, 17) ^ CYCLIC (x, 19) ^ (x >> 10)) /* It is unfortunate that C does not provide an operator for cyclic rotation. Hope the C compiler is smart enough. */ #define CYCLIC(w, s) ((w >> s) | (w << (32 - s))) /* Compute the message schedule according to FIPS 180-2:6.2.2 step 2. */ for (unsigned int t = 0; t < 16; ++t) { W[t] = SWAP (*words); ++words; } for (unsigned int t = 16; t < 64; ++t) W[t] = R1 (W[t - 2]) + W[t - 7] + R0 (W[t - 15]) + W[t - 16]; /* The actual computation according to FIPS 180-2:6.2.2 step 3. */ for (unsigned int t = 0; t < 64; ++t) { uint32_t T1 = h + S1 (e) + Ch (e, f, g) + K[t] + W[t]; uint32_t T2 = S0 (a) + Maj (a, b, c); h = g; g = f; f = e; e = d + T1; d = c; c = b; b = a; a = T1 + T2; } /* Add the starting values of the context according to FIPS 180-2:6.2.2 step 4. */ a += a_save; b += b_save; c += c_save; d += d_save; e += e_save; f += f_save; g += g_save; h += h_save; /* Prepare for the next round. */ nwords -= 16; } /* Put checksum in context given as argument. */ ctx->H[0] = a; ctx->H[1] = b; ctx->H[2] = c; ctx->H[3] = d; ctx->H[4] = e; ctx->H[5] = f; ctx->H[6] = g; ctx->H[7] = h; }