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Move mbedtls_cf_size_mask_ge function to the constant-time module
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
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@ -161,3 +161,19 @@ size_t mbedtls_cf_size_mask_lt( size_t x, size_t y )
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return( mask );
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}
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/*
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* Constant-flow mask generation for "greater or equal" comparison:
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* - if x >= y, return all bits 1, that is (size_t) -1
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* - otherwise, return all bits 0, that is 0
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*
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* This function can be used to write constant-time code by replacing branches
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* with bit operations using masks.
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*
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* This function is implemented without using comparison operators, as those
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* might be translated to branches by some compilers on some platforms.
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*/
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size_t mbedtls_cf_size_mask_ge( size_t x, size_t y )
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{
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return( ~mbedtls_cf_size_mask_lt( x, y ) );
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}
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@ -35,3 +35,5 @@ unsigned mbedtls_cf_uint_mask( unsigned value );
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size_t mbedtls_cf_size_mask( size_t bit );
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size_t mbedtls_cf_size_mask_lt( size_t x, size_t y );
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size_t mbedtls_cf_size_mask_ge( size_t x, size_t y );
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@ -1045,22 +1045,6 @@ int mbedtls_ssl_encrypt_buf( mbedtls_ssl_context *ssl,
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}
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#if defined(MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC)
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/*
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* Constant-flow mask generation for "greater or equal" comparison:
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* - if x >= y, return all bits 1, that is (size_t) -1
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* - otherwise, return all bits 0, that is 0
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*
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* This function can be used to write constant-time code by replacing branches
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* with bit operations using masks.
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*
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* This function is implemented without using comparison operators, as those
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* might be translated to branches by some compilers on some platforms.
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*/
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static size_t mbedtls_cf_size_mask_ge( size_t x, size_t y )
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{
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return( ~mbedtls_cf_size_mask_lt( x, y ) );
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}
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/*
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* Constant-flow boolean "equal" comparison:
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* return x == y
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