From 5197c6692c6d895956b833951079dcf4d937fd5c Mon Sep 17 00:00:00 2001 From: Gilles Peskine Date: Wed, 26 Aug 2020 17:03:24 +0200 Subject: [PATCH] Put local variables in a struct This way we can have a single call to mbedtls_platform_zeroize, which saves a few bytes of code size. Additionally, on my PC, I notice a significant speed improvement (x86_64 build with MBEDTLS_AESNI_C disabled, gcc 5.4.0 -O3). I don't have an explanation for that (I expected no measurable difference). Signed-off-by: Gilles Peskine --- library/aes.c | 162 +++++++++++++++++++++++--------------------------- 1 file changed, 76 insertions(+), 86 deletions(-) diff --git a/library/aes.c b/library/aes.c index 1d6560749..8b54e7eab 100644 --- a/library/aes.c +++ b/library/aes.c @@ -867,61 +867,56 @@ int mbedtls_internal_aes_encrypt( mbedtls_aes_context *ctx, unsigned char output[16] ) { int i; - uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3; + uint32_t *RK = ctx->rk; + struct + { + uint32_t X[4]; + uint32_t Y[4]; + } t; - RK = ctx->rk; - - GET_UINT32_LE( X0, input, 0 ); X0 ^= *RK++; - GET_UINT32_LE( X1, input, 4 ); X1 ^= *RK++; - GET_UINT32_LE( X2, input, 8 ); X2 ^= *RK++; - GET_UINT32_LE( X3, input, 12 ); X3 ^= *RK++; + GET_UINT32_LE( t.X[0], input, 0 ); t.X[0] ^= *RK++; + GET_UINT32_LE( t.X[1], input, 4 ); t.X[1] ^= *RK++; + GET_UINT32_LE( t.X[2], input, 8 ); t.X[2] ^= *RK++; + GET_UINT32_LE( t.X[3], input, 12 ); t.X[3] ^= *RK++; for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- ) { - AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 ); - AES_FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 ); + AES_FROUND( t.Y[0], t.Y[1], t.Y[2], t.Y[3], t.X[0], t.X[1], t.X[2], t.X[3] ); + AES_FROUND( t.X[0], t.X[1], t.X[2], t.X[3], t.Y[0], t.Y[1], t.Y[2], t.Y[3] ); } - AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 ); + AES_FROUND( t.Y[0], t.Y[1], t.Y[2], t.Y[3], t.X[0], t.X[1], t.X[2], t.X[3] ); - X0 = *RK++ ^ \ - ( (uint32_t) FSb[ ( Y0 ) & 0xFF ] ) ^ - ( (uint32_t) FSb[ ( Y1 >> 8 ) & 0xFF ] << 8 ) ^ - ( (uint32_t) FSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^ - ( (uint32_t) FSb[ ( Y3 >> 24 ) & 0xFF ] << 24 ); + t.X[0] = *RK++ ^ \ + ( (uint32_t) FSb[ ( t.Y[0] ) & 0xFF ] ) ^ + ( (uint32_t) FSb[ ( t.Y[1] >> 8 ) & 0xFF ] << 8 ) ^ + ( (uint32_t) FSb[ ( t.Y[2] >> 16 ) & 0xFF ] << 16 ) ^ + ( (uint32_t) FSb[ ( t.Y[3] >> 24 ) & 0xFF ] << 24 ); - X1 = *RK++ ^ \ - ( (uint32_t) FSb[ ( Y1 ) & 0xFF ] ) ^ - ( (uint32_t) FSb[ ( Y2 >> 8 ) & 0xFF ] << 8 ) ^ - ( (uint32_t) FSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^ - ( (uint32_t) FSb[ ( Y0 >> 24 ) & 0xFF ] << 24 ); + t.X[1] = *RK++ ^ \ + ( (uint32_t) FSb[ ( t.Y[1] ) & 0xFF ] ) ^ + ( (uint32_t) FSb[ ( t.Y[2] >> 8 ) & 0xFF ] << 8 ) ^ + ( (uint32_t) FSb[ ( t.Y[3] >> 16 ) & 0xFF ] << 16 ) ^ + ( (uint32_t) FSb[ ( t.Y[0] >> 24 ) & 0xFF ] << 24 ); - X2 = *RK++ ^ \ - ( (uint32_t) FSb[ ( Y2 ) & 0xFF ] ) ^ - ( (uint32_t) FSb[ ( Y3 >> 8 ) & 0xFF ] << 8 ) ^ - ( (uint32_t) FSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^ - ( (uint32_t) FSb[ ( Y1 >> 24 ) & 0xFF ] << 24 ); + t.X[2] = *RK++ ^ \ + ( (uint32_t) FSb[ ( t.Y[2] ) & 0xFF ] ) ^ + ( (uint32_t) FSb[ ( t.Y[3] >> 8 ) & 0xFF ] << 8 ) ^ + ( (uint32_t) FSb[ ( t.Y[0] >> 16 ) & 0xFF ] << 16 ) ^ + ( (uint32_t) FSb[ ( t.Y[1] >> 24 ) & 0xFF ] << 24 ); - X3 = *RK++ ^ \ - ( (uint32_t) FSb[ ( Y3 ) & 0xFF ] ) ^ - ( (uint32_t) FSb[ ( Y0 >> 8 ) & 0xFF ] << 8 ) ^ - ( (uint32_t) FSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^ - ( (uint32_t) FSb[ ( Y2 >> 24 ) & 0xFF ] << 24 ); + t.X[3] = *RK++ ^ \ + ( (uint32_t) FSb[ ( t.Y[3] ) & 0xFF ] ) ^ + ( (uint32_t) FSb[ ( t.Y[0] >> 8 ) & 0xFF ] << 8 ) ^ + ( (uint32_t) FSb[ ( t.Y[1] >> 16 ) & 0xFF ] << 16 ) ^ + ( (uint32_t) FSb[ ( t.Y[2] >> 24 ) & 0xFF ] << 24 ); - PUT_UINT32_LE( X0, output, 0 ); - PUT_UINT32_LE( X1, output, 4 ); - PUT_UINT32_LE( X2, output, 8 ); - PUT_UINT32_LE( X3, output, 12 ); + PUT_UINT32_LE( t.X[0], output, 0 ); + PUT_UINT32_LE( t.X[1], output, 4 ); + PUT_UINT32_LE( t.X[2], output, 8 ); + PUT_UINT32_LE( t.X[3], output, 12 ); - mbedtls_platform_zeroize( &X0, sizeof( X0 ) ); - mbedtls_platform_zeroize( &X1, sizeof( X1 ) ); - mbedtls_platform_zeroize( &X2, sizeof( X2 ) ); - mbedtls_platform_zeroize( &X3, sizeof( X3 ) ); - - mbedtls_platform_zeroize( &Y0, sizeof( Y0 ) ); - mbedtls_platform_zeroize( &Y1, sizeof( Y1 ) ); - mbedtls_platform_zeroize( &Y2, sizeof( Y2 ) ); - mbedtls_platform_zeroize( &Y3, sizeof( Y3 ) ); + mbedtls_platform_zeroize( &t, sizeof( t ) ); return( 0 ); } @@ -945,61 +940,56 @@ int mbedtls_internal_aes_decrypt( mbedtls_aes_context *ctx, unsigned char output[16] ) { int i; - uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3; + uint32_t *RK = ctx->rk; + struct + { + uint32_t X[4]; + uint32_t Y[4]; + } t; - RK = ctx->rk; - - GET_UINT32_LE( X0, input, 0 ); X0 ^= *RK++; - GET_UINT32_LE( X1, input, 4 ); X1 ^= *RK++; - GET_UINT32_LE( X2, input, 8 ); X2 ^= *RK++; - GET_UINT32_LE( X3, input, 12 ); X3 ^= *RK++; + GET_UINT32_LE( t.X[0], input, 0 ); t.X[0] ^= *RK++; + GET_UINT32_LE( t.X[1], input, 4 ); t.X[1] ^= *RK++; + GET_UINT32_LE( t.X[2], input, 8 ); t.X[2] ^= *RK++; + GET_UINT32_LE( t.X[3], input, 12 ); t.X[3] ^= *RK++; for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- ) { - AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 ); - AES_RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 ); + AES_RROUND( t.Y[0], t.Y[1], t.Y[2], t.Y[3], t.X[0], t.X[1], t.X[2], t.X[3] ); + AES_RROUND( t.X[0], t.X[1], t.X[2], t.X[3], t.Y[0], t.Y[1], t.Y[2], t.Y[3] ); } - AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 ); + AES_RROUND( t.Y[0], t.Y[1], t.Y[2], t.Y[3], t.X[0], t.X[1], t.X[2], t.X[3] ); - X0 = *RK++ ^ \ - ( (uint32_t) RSb[ ( Y0 ) & 0xFF ] ) ^ - ( (uint32_t) RSb[ ( Y3 >> 8 ) & 0xFF ] << 8 ) ^ - ( (uint32_t) RSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^ - ( (uint32_t) RSb[ ( Y1 >> 24 ) & 0xFF ] << 24 ); + t.X[0] = *RK++ ^ \ + ( (uint32_t) RSb[ ( t.Y[0] ) & 0xFF ] ) ^ + ( (uint32_t) RSb[ ( t.Y[3] >> 8 ) & 0xFF ] << 8 ) ^ + ( (uint32_t) RSb[ ( t.Y[2] >> 16 ) & 0xFF ] << 16 ) ^ + ( (uint32_t) RSb[ ( t.Y[1] >> 24 ) & 0xFF ] << 24 ); - X1 = *RK++ ^ \ - ( (uint32_t) RSb[ ( Y1 ) & 0xFF ] ) ^ - ( (uint32_t) RSb[ ( Y0 >> 8 ) & 0xFF ] << 8 ) ^ - ( (uint32_t) RSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^ - ( (uint32_t) RSb[ ( Y2 >> 24 ) & 0xFF ] << 24 ); + t.X[1] = *RK++ ^ \ + ( (uint32_t) RSb[ ( t.Y[1] ) & 0xFF ] ) ^ + ( (uint32_t) RSb[ ( t.Y[0] >> 8 ) & 0xFF ] << 8 ) ^ + ( (uint32_t) RSb[ ( t.Y[3] >> 16 ) & 0xFF ] << 16 ) ^ + ( (uint32_t) RSb[ ( t.Y[2] >> 24 ) & 0xFF ] << 24 ); - X2 = *RK++ ^ \ - ( (uint32_t) RSb[ ( Y2 ) & 0xFF ] ) ^ - ( (uint32_t) RSb[ ( Y1 >> 8 ) & 0xFF ] << 8 ) ^ - ( (uint32_t) RSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^ - ( (uint32_t) RSb[ ( Y3 >> 24 ) & 0xFF ] << 24 ); + t.X[2] = *RK++ ^ \ + ( (uint32_t) RSb[ ( t.Y[2] ) & 0xFF ] ) ^ + ( (uint32_t) RSb[ ( t.Y[1] >> 8 ) & 0xFF ] << 8 ) ^ + ( (uint32_t) RSb[ ( t.Y[0] >> 16 ) & 0xFF ] << 16 ) ^ + ( (uint32_t) RSb[ ( t.Y[3] >> 24 ) & 0xFF ] << 24 ); - X3 = *RK++ ^ \ - ( (uint32_t) RSb[ ( Y3 ) & 0xFF ] ) ^ - ( (uint32_t) RSb[ ( Y2 >> 8 ) & 0xFF ] << 8 ) ^ - ( (uint32_t) RSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^ - ( (uint32_t) RSb[ ( Y0 >> 24 ) & 0xFF ] << 24 ); + t.X[3] = *RK++ ^ \ + ( (uint32_t) RSb[ ( t.Y[3] ) & 0xFF ] ) ^ + ( (uint32_t) RSb[ ( t.Y[2] >> 8 ) & 0xFF ] << 8 ) ^ + ( (uint32_t) RSb[ ( t.Y[1] >> 16 ) & 0xFF ] << 16 ) ^ + ( (uint32_t) RSb[ ( t.Y[0] >> 24 ) & 0xFF ] << 24 ); - PUT_UINT32_LE( X0, output, 0 ); - PUT_UINT32_LE( X1, output, 4 ); - PUT_UINT32_LE( X2, output, 8 ); - PUT_UINT32_LE( X3, output, 12 ); + PUT_UINT32_LE( t.X[0], output, 0 ); + PUT_UINT32_LE( t.X[1], output, 4 ); + PUT_UINT32_LE( t.X[2], output, 8 ); + PUT_UINT32_LE( t.X[3], output, 12 ); - mbedtls_platform_zeroize( &X0, sizeof( X0 ) ); - mbedtls_platform_zeroize( &X1, sizeof( X1 ) ); - mbedtls_platform_zeroize( &X2, sizeof( X2 ) ); - mbedtls_platform_zeroize( &X3, sizeof( X3 ) ); - - mbedtls_platform_zeroize( &Y0, sizeof( Y0 ) ); - mbedtls_platform_zeroize( &Y1, sizeof( Y1 ) ); - mbedtls_platform_zeroize( &Y2, sizeof( Y2 ) ); - mbedtls_platform_zeroize( &Y3, sizeof( Y3 ) ); + mbedtls_platform_zeroize( &t, sizeof( t ) ); return( 0 ); }