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Protect get/put on secret data on sha256-module

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When reading the input, the buffer will be initialised with random data
and the reading will start from a random offset. When writing the data,
the output will be initialised with random data and the writing will
start from a random offset.
This commit is contained in:
Jarno Lamsa 2020-01-07 13:33:45 +02:00
parent 7d2434fac2
commit bb86c52430
1 changed files with 27 additions and 5 deletions
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32
library/sha256.c
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@ -196,11 +196,23 @@ int mbedtls_internal_sha256_process( mbedtls_sha256_context *ctx,
A[i] = ctx->state[i];
#if defined(MBEDTLS_SHA256_SMALLER)
{
uint32_t offset = mbedtls_platform_random_in_range(16);
mbedtls_platform_memset( W, 0, sizeof( W ) );
for( i = offset; i < 16; i++ )
{
W[i] = (uint32_t)mbedtls_platform_get_uint32_be( &data[4 * i] );
}
for( i = 0; i < offset; i++ )
{
W[i] = (uint32_t)mbedtls_platform_get_uint32_be( &data[4 * i] );
}
}
for( i = 0; i < 64; i++ )
{
if( i < 16 )
W[i] = (uint32_t)mbedtls_platform_get_uint32_be( &data[4 * i] );
else
if( i >= 16 )
R( i );
P( A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], W[i], K[i] );
@ -323,6 +335,7 @@ int mbedtls_sha256_finish_ret( mbedtls_sha256_context *ctx,
int ret, s_pos, o_pos;
uint32_t used;
uint32_t high, low;
uint32_t offset = 0;
SHA256_VALIDATE_RET( ctx != NULL );
SHA256_VALIDATE_RET( (unsigned char *)output != NULL );
@ -366,11 +379,15 @@ int mbedtls_sha256_finish_ret( mbedtls_sha256_context *ctx,
/*
* Output final state
*/
offset = mbedtls_platform_random_in_range(7);
for( s_pos = 0, o_pos = 0; s_pos < 7; s_pos++, o_pos += 4 )
mbedtls_platform_memset( output, 0, 32 );
for( s_pos = offset, o_pos = offset * 4; s_pos < 7;
s_pos++, o_pos += 4 )
{
(void)mbedtls_platform_put_uint32_be( &output[o_pos],
ctx->state[s_pos] );
ctx->state[s_pos] );
}
#if !defined(MBEDTLS_SHA256_NO_SHA224)
@ -378,6 +395,11 @@ int mbedtls_sha256_finish_ret( mbedtls_sha256_context *ctx,
#endif
(void)mbedtls_platform_put_uint32_be( &output[28], ctx->state[7] );
for( s_pos = 0, o_pos = 0; s_pos < (int)offset; s_pos++, o_pos += 4 )
{
(void)mbedtls_platform_put_uint32_be( &output[o_pos],
ctx->state[s_pos] );
}
return( 0 );
}