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Merge pull request #2257 from dgarske/sha256_regs

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Added faster SHA256 build options
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toddouska 2019-06-04 14:05:54 -07:00 committed by GitHub
commit fee81ce49e
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1 changed files with 96 additions and 0 deletions
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wolfcrypt/src/sha256.c
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@ -25,6 +25,24 @@
#include <wolfssl/wolfcrypt/settings.h>
/*
* SHA256 Build Options:
* USE_SLOW_SHA256: Reduces code size by not partially unrolling
(~2KB smaller and ~25% slower) (default OFF)
* WOLFSSL_SHA256_BY_SPEC: Uses the Ch/Maj based on SHA256 specification
(default ON)
* WOLFSSL_SHA256_ALT_CH_MAJ: Alternate Ch/Maj that is easier for compilers to
optimize and recognize as SHA256 (default OFF)
* SHA256_MANY_REGISTERS: A SHA256 version that keeps all data in registers
and partial unrolled (default OFF)
*/
/* Default SHA256 to use Ch/Maj based on specification */
#if !defined(WOLFSSL_SHA256_BY_SPEC) && !defined(WOLFSSL_SHA256_ALT_CH_MAJ)
#define WOLFSSL_SHA256_BY_SPEC
#endif
#if !defined(NO_SHA256) && !defined(WOLFSSL_ARMASM)
#if defined(HAVE_FIPS) && \
@ -582,8 +600,17 @@ static int InitSha256(wc_Sha256* sha256)
0x90BEFFFAL, 0xA4506CEBL, 0xBEF9A3F7L, 0xC67178F2L
};
/* Both versions of Ch and Maj are logically the same, but with the second set
the compilers can recognize them better for optimization */
#ifdef WOLFSSL_SHA256_BY_SPEC
/* SHA256 math based on specification */
#define Ch(x,y,z) ((z) ^ ((x) & ((y) ^ (z))))
#define Maj(x,y,z) ((((x) | (y)) & (z)) | ((x) & (y)))
#else
/* SHA256 math reworked for easier compiler optimization */
#define Ch(x,y,z) ((((y) ^ (z)) & (x)) ^ (z))
#define Maj(x,y,z) ((((x) ^ (y)) & ((y) ^ (z))) ^ (y))
#endif
#define R(x, n) (((x) & 0xFFFFFFFFU) >> (n))
#define S(x, n) rotrFixed(x, n)
@ -601,6 +628,7 @@ static int InitSha256(wc_Sha256* sha256)
#define g(i) S[(6-i) & 7]
#define h(i) S[(7-i) & 7]
#ifndef SHA256_MANY_REGISTERS
#define RND(j) \
t0 = h(j) + Sigma1(e(j)) + Ch(e(j), f(j), g(j)) + K[i+j] + W[i+j]; \
t1 = Sigma0(a(j)) + Maj(a(j), b(j), c(j)); \
@ -672,6 +700,74 @@ static int InitSha256(wc_Sha256* sha256)
#endif
return 0;
}
#else
/* SHA256 version that keeps all data in registers */
#define SCHED1(j) (W[j] = sha256->buffer[j])
#define SCHED(j) ( \
W[ j & 15] += \
Gamma1(W[(j-2) & 15])+ \
W[(j-7) & 15] + \
Gamma0(W[(j-15) & 15]) \
)
#define RND1(j) \
t0 = h(j) + Sigma1(e(j)) + Ch(e(j), f(j), g(j)) + K[i+j] + SCHED1(j); \
t1 = Sigma0(a(j)) + Maj(a(j), b(j), c(j)); \
d(j) += t0; \
h(j) = t0 + t1
#define RNDN(j) \
t0 = h(j) + Sigma1(e(j)) + Ch(e(j), f(j), g(j)) + K[i+j] + SCHED(j); \
t1 = Sigma0(a(j)) + Maj(a(j), b(j), c(j)); \
d(j) += t0; \
h(j) = t0 + t1
#ifndef XTRANSFORM
#define XTRANSFORM(S) Transform_Sha256((S))
#define XTRANSFORM_LEN(S, D, L) Transform_Sha256_Len((S),(D),(L))
#endif
static int Transform_Sha256(wc_Sha256* sha256)
{
word32 S[8], t0, t1;
int i;
word32 W[WC_SHA256_BLOCK_SIZE/sizeof(word32)];
/* Copy digest to working vars */
S[0] = sha256->digest[0];
S[1] = sha256->digest[1];
S[2] = sha256->digest[2];
S[3] = sha256->digest[3];
S[4] = sha256->digest[4];
S[5] = sha256->digest[5];
S[6] = sha256->digest[6];
S[7] = sha256->digest[7];
i = 0;
RND1( 0); RND1( 1); RND1( 2); RND1( 3);
RND1( 4); RND1( 5); RND1( 6); RND1( 7);
RND1( 8); RND1( 9); RND1(10); RND1(11);
RND1(12); RND1(13); RND1(14); RND1(15);
/* 64 operations, partially loop unrolled */
for (i = 16; i < 64; i += 16) {
RNDN( 0); RNDN( 1); RNDN( 2); RNDN( 3);
RNDN( 4); RNDN( 5); RNDN( 6); RNDN( 7);
RNDN( 8); RNDN( 9); RNDN(10); RNDN(11);
RNDN(12); RNDN(13); RNDN(14); RNDN(15);
}
/* Add the working vars back into digest */
sha256->digest[0] += S[0];
sha256->digest[1] += S[1];
sha256->digest[2] += S[2];
sha256->digest[3] += S[3];
sha256->digest[4] += S[4];
sha256->digest[5] += S[5];
sha256->digest[6] += S[6];
sha256->digest[7] += S[7];
return 0;
}
#endif /* SHA256_MANY_REGISTERS */
#endif
/* End wc_ software implementation */