Make SHA-2 implementation smaller
Adjust the size/performance trade-off:
* Reduces size of sha256_process() from 7.4KB to 2KB on ARMv7-M
* Reduces performance by less than 14% on Cortex-M4
* Seems to even improve performance on my Core i7
diff --git a/library/sha256.c b/library/sha256.c
index 5c12638..f80c2b8 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -130,27 +130,25 @@
}
#if !defined(MBEDTLS_SHA256_PROCESS_ALT)
-void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[64] )
+static const uint32_t K[] =
{
- uint32_t temp1, temp2, W[64];
- uint32_t A, B, C, D, E, F, G, H;
-
- GET_UINT32_BE( W[ 0], data, 0 );
- GET_UINT32_BE( W[ 1], data, 4 );
- GET_UINT32_BE( W[ 2], data, 8 );
- GET_UINT32_BE( W[ 3], data, 12 );
- GET_UINT32_BE( W[ 4], data, 16 );
- GET_UINT32_BE( W[ 5], data, 20 );
- GET_UINT32_BE( W[ 6], data, 24 );
- GET_UINT32_BE( W[ 7], data, 28 );
- GET_UINT32_BE( W[ 8], data, 32 );
- GET_UINT32_BE( W[ 9], data, 36 );
- GET_UINT32_BE( W[10], data, 40 );
- GET_UINT32_BE( W[11], data, 44 );
- GET_UINT32_BE( W[12], data, 48 );
- GET_UINT32_BE( W[13], data, 52 );
- GET_UINT32_BE( W[14], data, 56 );
- GET_UINT32_BE( W[15], data, 60 );
+ 0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5,
+ 0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5,
+ 0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3,
+ 0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174,
+ 0xE49B69C1, 0xEFBE4786, 0x0FC19DC6, 0x240CA1CC,
+ 0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA,
+ 0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7,
+ 0xC6E00BF3, 0xD5A79147, 0x06CA6351, 0x14292967,
+ 0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13,
+ 0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85,
+ 0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3,
+ 0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070,
+ 0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5,
+ 0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3,
+ 0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208,
+ 0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2,
+};
#define SHR(x,n) ((x & 0xFFFFFFFF) >> n)
#define ROTR(x,n) (SHR(x,n) | (x << (32 - n)))
@@ -177,88 +175,44 @@
d += temp1; h = temp1 + temp2; \
}
- A = ctx->state[0];
- B = ctx->state[1];
- C = ctx->state[2];
- D = ctx->state[3];
- E = ctx->state[4];
- F = ctx->state[5];
- G = ctx->state[6];
- H = ctx->state[7];
+void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[64] )
+{
+ uint32_t temp1, temp2, W[64];
+ uint32_t A[8];
+ unsigned int i;
- P( A, B, C, D, E, F, G, H, W[ 0], 0x428A2F98 );
- P( H, A, B, C, D, E, F, G, W[ 1], 0x71374491 );
- P( G, H, A, B, C, D, E, F, W[ 2], 0xB5C0FBCF );
- P( F, G, H, A, B, C, D, E, W[ 3], 0xE9B5DBA5 );
- P( E, F, G, H, A, B, C, D, W[ 4], 0x3956C25B );
- P( D, E, F, G, H, A, B, C, W[ 5], 0x59F111F1 );
- P( C, D, E, F, G, H, A, B, W[ 6], 0x923F82A4 );
- P( B, C, D, E, F, G, H, A, W[ 7], 0xAB1C5ED5 );
- P( A, B, C, D, E, F, G, H, W[ 8], 0xD807AA98 );
- P( H, A, B, C, D, E, F, G, W[ 9], 0x12835B01 );
- P( G, H, A, B, C, D, E, F, W[10], 0x243185BE );
- P( F, G, H, A, B, C, D, E, W[11], 0x550C7DC3 );
- P( E, F, G, H, A, B, C, D, W[12], 0x72BE5D74 );
- P( D, E, F, G, H, A, B, C, W[13], 0x80DEB1FE );
- P( C, D, E, F, G, H, A, B, W[14], 0x9BDC06A7 );
- P( B, C, D, E, F, G, H, A, W[15], 0xC19BF174 );
- P( A, B, C, D, E, F, G, H, R(16), 0xE49B69C1 );
- P( H, A, B, C, D, E, F, G, R(17), 0xEFBE4786 );
- P( G, H, A, B, C, D, E, F, R(18), 0x0FC19DC6 );
- P( F, G, H, A, B, C, D, E, R(19), 0x240CA1CC );
- P( E, F, G, H, A, B, C, D, R(20), 0x2DE92C6F );
- P( D, E, F, G, H, A, B, C, R(21), 0x4A7484AA );
- P( C, D, E, F, G, H, A, B, R(22), 0x5CB0A9DC );
- P( B, C, D, E, F, G, H, A, R(23), 0x76F988DA );
- P( A, B, C, D, E, F, G, H, R(24), 0x983E5152 );
- P( H, A, B, C, D, E, F, G, R(25), 0xA831C66D );
- P( G, H, A, B, C, D, E, F, R(26), 0xB00327C8 );
- P( F, G, H, A, B, C, D, E, R(27), 0xBF597FC7 );
- P( E, F, G, H, A, B, C, D, R(28), 0xC6E00BF3 );
- P( D, E, F, G, H, A, B, C, R(29), 0xD5A79147 );
- P( C, D, E, F, G, H, A, B, R(30), 0x06CA6351 );
- P( B, C, D, E, F, G, H, A, R(31), 0x14292967 );
- P( A, B, C, D, E, F, G, H, R(32), 0x27B70A85 );
- P( H, A, B, C, D, E, F, G, R(33), 0x2E1B2138 );
- P( G, H, A, B, C, D, E, F, R(34), 0x4D2C6DFC );
- P( F, G, H, A, B, C, D, E, R(35), 0x53380D13 );
- P( E, F, G, H, A, B, C, D, R(36), 0x650A7354 );
- P( D, E, F, G, H, A, B, C, R(37), 0x766A0ABB );
- P( C, D, E, F, G, H, A, B, R(38), 0x81C2C92E );
- P( B, C, D, E, F, G, H, A, R(39), 0x92722C85 );
- P( A, B, C, D, E, F, G, H, R(40), 0xA2BFE8A1 );
- P( H, A, B, C, D, E, F, G, R(41), 0xA81A664B );
- P( G, H, A, B, C, D, E, F, R(42), 0xC24B8B70 );
- P( F, G, H, A, B, C, D, E, R(43), 0xC76C51A3 );
- P( E, F, G, H, A, B, C, D, R(44), 0xD192E819 );
- P( D, E, F, G, H, A, B, C, R(45), 0xD6990624 );
- P( C, D, E, F, G, H, A, B, R(46), 0xF40E3585 );
- P( B, C, D, E, F, G, H, A, R(47), 0x106AA070 );
- P( A, B, C, D, E, F, G, H, R(48), 0x19A4C116 );
- P( H, A, B, C, D, E, F, G, R(49), 0x1E376C08 );
- P( G, H, A, B, C, D, E, F, R(50), 0x2748774C );
- P( F, G, H, A, B, C, D, E, R(51), 0x34B0BCB5 );
- P( E, F, G, H, A, B, C, D, R(52), 0x391C0CB3 );
- P( D, E, F, G, H, A, B, C, R(53), 0x4ED8AA4A );
- P( C, D, E, F, G, H, A, B, R(54), 0x5B9CCA4F );
- P( B, C, D, E, F, G, H, A, R(55), 0x682E6FF3 );
- P( A, B, C, D, E, F, G, H, R(56), 0x748F82EE );
- P( H, A, B, C, D, E, F, G, R(57), 0x78A5636F );
- P( G, H, A, B, C, D, E, F, R(58), 0x84C87814 );
- P( F, G, H, A, B, C, D, E, R(59), 0x8CC70208 );
- P( E, F, G, H, A, B, C, D, R(60), 0x90BEFFFA );
- P( D, E, F, G, H, A, B, C, R(61), 0xA4506CEB );
- P( C, D, E, F, G, H, A, B, R(62), 0xBEF9A3F7 );
- P( B, C, D, E, F, G, H, A, R(63), 0xC67178F2 );
+ for( i = 0; i < 16; i++ )
+ GET_UINT32_BE( W[i], data, 4 * i );
- ctx->state[0] += A;
- ctx->state[1] += B;
- ctx->state[2] += C;
- ctx->state[3] += D;
- ctx->state[4] += E;
- ctx->state[5] += F;
- ctx->state[6] += G;
- ctx->state[7] += H;
+ for( i = 0; i < 8; i++ )
+ A[i] = ctx->state[i];
+
+ for( i = 0; i < 16; i += 8 )
+ {
+ P( A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], W[i+0], K[i+0] );
+ P( A[7], A[0], A[1], A[2], A[3], A[4], A[5], A[6], W[i+1], K[i+1] );
+ P( A[6], A[7], A[0], A[1], A[2], A[3], A[4], A[5], W[i+2], K[i+2] );
+ P( A[5], A[6], A[7], A[0], A[1], A[2], A[3], A[4], W[i+3], K[i+3] );
+ P( A[4], A[5], A[6], A[7], A[0], A[1], A[2], A[3], W[i+4], K[i+4] );
+ P( A[3], A[4], A[5], A[6], A[7], A[0], A[1], A[2], W[i+5], K[i+5] );
+ P( A[2], A[3], A[4], A[5], A[6], A[7], A[0], A[1], W[i+6], K[i+6] );
+ P( A[1], A[2], A[3], A[4], A[5], A[6], A[7], A[0], W[i+7], K[i+7] );
+ }
+
+ for( i = 16; i < 64; i += 8 )
+ {
+ P( A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], R(i+0), K[i+0] );
+ P( A[7], A[0], A[1], A[2], A[3], A[4], A[5], A[6], R(i+1), K[i+1] );
+ P( A[6], A[7], A[0], A[1], A[2], A[3], A[4], A[5], R(i+2), K[i+2] );
+ P( A[5], A[6], A[7], A[0], A[1], A[2], A[3], A[4], R(i+3), K[i+3] );
+ P( A[4], A[5], A[6], A[7], A[0], A[1], A[2], A[3], R(i+4), K[i+4] );
+ P( A[3], A[4], A[5], A[6], A[7], A[0], A[1], A[2], R(i+5), K[i+5] );
+ P( A[2], A[3], A[4], A[5], A[6], A[7], A[0], A[1], R(i+6), K[i+6] );
+ P( A[1], A[2], A[3], A[4], A[5], A[6], A[7], A[0], R(i+7), K[i+7] );
+ }
+
+ for( i = 0; i < 8; i++ )
+ ctx->state[i] += A[i];
}
#endif /* !MBEDTLS_SHA256_PROCESS_ALT */