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[crypto] Eliminate temporary working space for bigint_reduce()
Direct modular reduction is expected to be used in situations where there is no requirement to retain the original (unreduced) value. Modify the API for bigint_reduce() to reduce the value in place, (removing the separate result buffer), impose a constraint that the modulus and value have the same size, and require the modulus to be passed in writable memory (to allow for scaling in place). This removes the requirement for additional temporary working space. Reverse the order of arguments so that the constant input is first, to match the usage pattern for bigint_add() et al. Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
@@ -185,19 +185,14 @@ void bigint_multiply_sample ( const bigint_element_t *multiplicand0,
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bigint_multiply ( multiplicand, multiplier, result );
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}
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void bigint_reduce_sample ( const bigint_element_t *minuend0,
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unsigned int minuend_size,
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const bigint_element_t *modulus0,
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unsigned int modulus_size,
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bigint_element_t *result0, void *tmp ) {
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const bigint_t ( minuend_size ) __attribute__ (( may_alias ))
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*minuend = ( ( const void * ) minuend0 );
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const bigint_t ( modulus_size ) __attribute__ (( may_alias ))
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*modulus = ( ( const void * ) modulus0 );
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bigint_t ( modulus_size ) __attribute__ (( may_alias ))
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*result = ( ( void * ) result0 );
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void bigint_reduce_sample ( bigint_element_t *modulus0,
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bigint_element_t *value0, unsigned int size ) {
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bigint_t ( size ) __attribute__ (( may_alias ))
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*modulus = ( ( void * ) modulus0 );
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bigint_t ( size ) __attribute__ (( may_alias ))
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*value = ( ( void * ) value0 );
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bigint_reduce ( minuend, modulus, result, tmp );
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bigint_reduce ( modulus, value );
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}
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void bigint_mod_invert_sample ( const bigint_element_t *invertend0,
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@@ -555,43 +550,40 @@ void bigint_mod_exp_sample ( const bigint_element_t *base0,
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/**
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* Report result of big integer modular direct reduction test
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*
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* @v minuend Big integer to be reduced
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* @v modulus Big integer modulus
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* @v value Big integer to be reduced
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* @v expected Big integer expected result
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*/
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#define bigint_reduce_ok( minuend, modulus, expected ) do { \
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static const uint8_t minuend_raw[] = minuend; \
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#define bigint_reduce_ok( modulus, value, expected ) do { \
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static const uint8_t modulus_raw[] = modulus; \
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static const uint8_t value_raw[] = value; \
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static const uint8_t expected_raw[] = expected; \
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uint8_t result_raw[ sizeof ( expected_raw ) ]; \
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unsigned int minuend_size = \
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bigint_required_size ( sizeof ( minuend_raw ) ); \
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unsigned int modulus_size = \
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unsigned int size = \
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bigint_required_size ( sizeof ( modulus_raw ) ); \
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bigint_t ( minuend_size ) minuend_temp; \
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bigint_t ( modulus_size ) modulus_temp; \
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bigint_t ( modulus_size ) result_temp; \
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size_t tmp_len = bigint_reduce_tmp_len ( &minuend_temp ); \
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uint8_t tmp[tmp_len]; \
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bigint_t ( size ) modulus_temp; \
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bigint_t ( size ) value_temp; \
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{} /* Fix emacs alignment */ \
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\
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assert ( bigint_size ( &result_temp ) == \
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bigint_size ( &modulus_temp ) ); \
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bigint_init ( &minuend_temp, minuend_raw, \
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sizeof ( minuend_raw ) ); \
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assert ( bigint_size ( &modulus_temp ) == \
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bigint_size ( &value_temp ) ); \
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bigint_init ( &modulus_temp, modulus_raw, \
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sizeof ( modulus_raw ) ); \
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bigint_init ( &value_temp, value_raw, sizeof ( value_raw ) ); \
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DBG ( "Modular reduce:\n" ); \
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DBG_HDA ( 0, &minuend_temp, sizeof ( minuend_temp ) ); \
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DBG_HDA ( 0, &modulus_temp, sizeof ( modulus_temp ) ); \
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bigint_reduce ( &minuend_temp, &modulus_temp, &result_temp, \
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tmp ); \
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DBG_HDA ( 0, &result_temp, sizeof ( result_temp ) ); \
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bigint_done ( &result_temp, result_raw, \
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sizeof ( result_raw ) ); \
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DBG_HDA ( 0, &value_temp, sizeof ( value_temp ) ); \
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bigint_reduce ( &modulus_temp, &value_temp ); \
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DBG_HDA ( 0, &value_temp, sizeof ( value_temp ) ); \
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bigint_done ( &value_temp, result_raw, sizeof ( result_raw ) ); \
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\
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ok ( memcmp ( result_raw, expected_raw, \
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sizeof ( result_raw ) ) == 0 ); \
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\
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bigint_init ( &value_temp, modulus_raw, \
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sizeof ( modulus_raw ) ); \
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ok ( memcmp ( &modulus_temp, &value_temp, \
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sizeof ( modulus_temp ) ) == 0 ); \
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} while ( 0 )
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/**
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@@ -1797,16 +1789,16 @@ static void bigint_test_exec ( void ) {
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x01 ) );
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bigint_reduce_ok ( BIGINT ( 0x00 ),
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BIGINT ( 0xaf ),
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bigint_reduce_ok ( BIGINT ( 0xaf ),
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BIGINT ( 0x00 ),
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BIGINT ( 0x00 ) );
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bigint_reduce_ok ( BIGINT ( 0xab ),
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BIGINT ( 0xab ),
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BIGINT ( 0x00 ) );
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bigint_reduce_ok ( BIGINT ( 0x1d, 0x97, 0x63, 0xc9, 0x97, 0xcd, 0x43,
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0xcb, 0x8e, 0x71, 0xac, 0x41, 0xdd ),
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BIGINT ( 0xcc, 0x9d, 0xa0, 0x79, 0x96, 0x6a, 0x46,
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bigint_reduce_ok ( BIGINT ( 0xcc, 0x9d, 0xa0, 0x79, 0x96, 0x6a, 0x46,
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0xd5, 0xb4, 0x30, 0xd2, 0x2b, 0xbf ),
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BIGINT ( 0x1d, 0x97, 0x63, 0xc9, 0x97, 0xcd, 0x43,
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0xcb, 0x8e, 0x71, 0xac, 0x41, 0xdd ),
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BIGINT ( 0x1d, 0x97, 0x63, 0xc9, 0x97, 0xcd, 0x43,
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0xcb, 0x8e, 0x71, 0xac, 0x41, 0xdd ) );
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bigint_reduce_ok ( BIGINT ( 0x21, 0xfa, 0x4f, 0xce, 0x0f, 0x0f, 0x4d,
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@@ -1815,15 +1807,19 @@ static void bigint_test_exec ( void ) {
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0x43, 0xaa, 0xad, 0x21, 0x30, 0xe5 ),
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BIGINT ( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ) );
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bigint_reduce_ok ( BIGINT ( 0xf9, 0x78, 0x96, 0x39, 0xee, 0x98, 0x42,
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bigint_reduce_ok ( BIGINT ( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0xf3, 0x65, 0x35, 0x41,
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0x66, 0x65 ),
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BIGINT ( 0xf9, 0x78, 0x96, 0x39, 0xee, 0x98, 0x42,
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0x6a, 0xb8, 0x74, 0x0b, 0xe8, 0x5c, 0x76,
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0x34, 0xaf ),
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BIGINT ( 0xf3, 0x65, 0x35, 0x41, 0x66, 0x65 ),
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BIGINT ( 0xb3, 0x07, 0xe8, 0xb7, 0x01, 0xf6 ) );
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bigint_reduce_ok ( BIGINT ( 0xfe, 0x30, 0xe1, 0xc6, 0x65, 0x97, 0x48,
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0x2e, 0x94, 0xd4 ),
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BIGINT ( 0x47, 0xaa, 0x88, 0x00, 0xd0, 0x30, 0x62,
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BIGINT ( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0xb3, 0x07, 0xe8, 0xb7,
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0x01, 0xf6 ) );
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bigint_reduce_ok ( BIGINT ( 0x47, 0xaa, 0x88, 0x00, 0xd0, 0x30, 0x62,
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0xfb, 0x5d, 0x55 ),
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BIGINT ( 0xfe, 0x30, 0xe1, 0xc6, 0x65, 0x97, 0x48,
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0x2e, 0x94, 0xd4 ),
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BIGINT ( 0x27, 0x31, 0x49, 0xc3, 0xf5, 0x06, 0x1f,
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0x3c, 0x7c, 0xd5 ) );
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bigint_mod_invert_ok ( BIGINT ( 0x01 ), BIGINT ( 0x01 ) );
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