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https://github.com/ipxe/ipxe
synced 2026-01-22 03:32:59 +03:00
[crypto] Expose carry flag from big integer addition and subtraction
Expose the effective carry (or borrow) out flag from big integer addition and subtraction, and use this to elide an explicit bit test when performing x25519 reduction. Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
@@ -58,24 +58,24 @@ void bigint_done_sample ( const bigint_element_t *value0, unsigned int size,
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bigint_done ( value, out, len );
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}
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void bigint_add_sample ( const bigint_element_t *addend0,
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bigint_element_t *value0, unsigned int size ) {
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int bigint_add_sample ( const bigint_element_t *addend0,
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bigint_element_t *value0, unsigned int size ) {
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const bigint_t ( size ) *addend __attribute__ (( may_alias ))
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= ( ( const void * ) addend0 );
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bigint_t ( size ) *value __attribute__ (( may_alias ))
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= ( ( void * ) value0 );
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bigint_add ( addend, value );
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return bigint_add ( addend, value );
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}
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void bigint_subtract_sample ( const bigint_element_t *subtrahend0,
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bigint_element_t *value0, unsigned int size ) {
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int bigint_subtract_sample ( const bigint_element_t *subtrahend0,
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bigint_element_t *value0, unsigned int size ) {
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const bigint_t ( size ) *subtrahend __attribute__ (( may_alias ))
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= ( ( const void * ) subtrahend0 );
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bigint_t ( size ) *value __attribute__ (( may_alias ))
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= ( ( void * ) value0 );
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bigint_subtract ( subtrahend, value );
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return bigint_subtract ( subtrahend, value );
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}
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void bigint_shl_sample ( bigint_element_t *value0, unsigned int size ) {
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@@ -253,16 +253,19 @@ void bigint_mod_exp_sample ( const bigint_element_t *base0,
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* @v addend Big integer to add
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* @v value Big integer to be added to
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* @v expected Big integer expected result
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* @v overflow Expected result overflows range
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*/
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#define bigint_add_ok( addend, value, expected ) do { \
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#define bigint_add_ok( addend, value, expected, overflow ) do { \
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static const uint8_t addend_raw[] = addend; \
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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 size = \
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bigint_required_size ( sizeof ( value_raw ) ); \
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unsigned int msb = ( 8 * sizeof ( value_raw ) ); \
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bigint_t ( size ) addend_temp; \
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bigint_t ( size ) value_temp; \
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int carry; \
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{} /* Fix emacs alignment */ \
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\
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assert ( bigint_size ( &addend_temp ) == \
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@@ -273,12 +276,15 @@ void bigint_mod_exp_sample ( const bigint_element_t *base0,
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DBG ( "Add:\n" ); \
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DBG_HDA ( 0, &addend_temp, sizeof ( addend_temp ) ); \
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DBG_HDA ( 0, &value_temp, sizeof ( value_temp ) ); \
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bigint_add ( &addend_temp, &value_temp ); \
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carry = bigint_add ( &addend_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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if ( sizeof ( result_raw ) < sizeof ( value_temp ) ) \
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carry += bigint_bit_is_set ( &value_temp, msb ); \
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ok ( carry == overflow ); \
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} while ( 0 )
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/**
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@@ -287,8 +293,10 @@ void bigint_mod_exp_sample ( const bigint_element_t *base0,
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* @v subtrahend Big integer to subtract
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* @v value Big integer to be subtracted from
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* @v expected Big integer expected result
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* @v underflow Expected result underflows range
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*/
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#define bigint_subtract_ok( subtrahend, value, expected ) do { \
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#define bigint_subtract_ok( subtrahend, value, expected, \
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underflow ) do { \
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static const uint8_t subtrahend_raw[] = subtrahend; \
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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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@@ -297,6 +305,7 @@ void bigint_mod_exp_sample ( const bigint_element_t *base0,
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bigint_required_size ( sizeof ( value_raw ) ); \
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bigint_t ( size ) subtrahend_temp; \
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bigint_t ( size ) value_temp; \
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int borrow; \
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{} /* Fix emacs alignment */ \
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\
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assert ( bigint_size ( &subtrahend_temp ) == \
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@@ -307,12 +316,13 @@ void bigint_mod_exp_sample ( const bigint_element_t *base0,
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DBG ( "Subtract:\n" ); \
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DBG_HDA ( 0, &subtrahend_temp, sizeof ( subtrahend_temp ) ); \
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DBG_HDA ( 0, &value_temp, sizeof ( value_temp ) ); \
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bigint_subtract ( &subtrahend_temp, &value_temp ); \
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borrow = bigint_subtract ( &subtrahend_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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ok ( borrow == underflow ); \
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} while ( 0 )
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/**
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@@ -724,16 +734,28 @@ static void bigint_test_exec ( void ) {
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bigint_add_ok ( BIGINT ( 0x8a ),
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BIGINT ( 0x43 ),
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BIGINT ( 0xcd ) );
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BIGINT ( 0xcd ), 0 );
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bigint_add_ok ( BIGINT ( 0xc5, 0x7b ),
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BIGINT ( 0xd6, 0xb1 ),
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BIGINT ( 0x9c, 0x2c ) );
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BIGINT ( 0x9c, 0x2c ), 1 );
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bigint_add_ok ( BIGINT ( 0xf9, 0xd9, 0xdc ),
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BIGINT ( 0x6d, 0x4b, 0xca ),
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BIGINT ( 0x67, 0x25, 0xa6 ) );
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BIGINT ( 0x67, 0x25, 0xa6 ), 1 );
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bigint_add_ok ( BIGINT ( 0xdd, 0xc2, 0x20, 0x5f ),
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BIGINT ( 0x80, 0x32, 0xc4, 0xb0 ),
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BIGINT ( 0x5d, 0xf4, 0xe5, 0x0f ) );
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BIGINT ( 0x5d, 0xf4, 0xe5, 0x0f ), 1 );
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bigint_add_ok ( BIGINT ( 0x5e, 0x46, 0x4d, 0xc6, 0xa2, 0x7d, 0x45,
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0xc3 ),
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BIGINT ( 0xd6, 0xc0, 0xd7, 0xd4, 0xf6, 0x04, 0x47,
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0xed ),
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BIGINT ( 0x35, 0x07, 0x25, 0x9b, 0x98, 0x81, 0x8d,
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0xb0 ), 1 );
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bigint_add_ok ( BIGINT ( 0x0e, 0x46, 0x4d, 0xc6, 0xa2, 0x7d, 0x45,
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0xc3 ),
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BIGINT ( 0xd6, 0xc0, 0xd7, 0xd4, 0xf6, 0x04, 0x47,
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0xed ),
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BIGINT ( 0xe5, 0x07, 0x25, 0x9b, 0x98, 0x81, 0x8d,
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0xb0 ), 0 );
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bigint_add_ok ( BIGINT ( 0x01, 0xed, 0x45, 0x4b, 0x41, 0xeb, 0x4c,
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0x2e, 0x53, 0x07, 0x15, 0x51, 0x56, 0x47,
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0x29, 0xfc, 0x9c, 0xbd, 0xbd, 0xfb, 0x1b,
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@@ -745,7 +767,7 @@ static void bigint_test_exec ( void ) {
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BIGINT ( 0x75, 0xdb, 0x41, 0x80, 0x73, 0x0e, 0x23,
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0xe0, 0x3d, 0x98, 0x70, 0x36, 0x11, 0x03,
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0xcb, 0x35, 0x0f, 0x6c, 0x09, 0x17, 0xdc,
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0xd6, 0xd0 ) );
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0xd6, 0xd0 ), 0 );
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bigint_add_ok ( BIGINT ( 0x06, 0x8e, 0xd6, 0x18, 0xbb, 0x4b, 0x0c,
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0xc5, 0x85, 0xde, 0xee, 0x9b, 0x3f, 0x65,
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0x63, 0x86, 0xf5, 0x5a, 0x9f, 0xa2, 0xd7,
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@@ -802,19 +824,19 @@ static void bigint_test_exec ( void ) {
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0x68, 0x76, 0xf5, 0x20, 0xa1, 0xa8, 0x1a,
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0x9f, 0x60, 0x58, 0xff, 0xb6, 0x76, 0x45,
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0xe6, 0xed, 0x61, 0x8d, 0xe6, 0xc0, 0x72,
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0x1c, 0x07 ) );
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0x1c, 0x07 ), 0 );
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bigint_subtract_ok ( BIGINT ( 0x83 ),
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BIGINT ( 0x50 ),
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BIGINT ( 0xcd ) );
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BIGINT ( 0xcd ), 1 );
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bigint_subtract_ok ( BIGINT ( 0x2c, 0x7c ),
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BIGINT ( 0x49, 0x0e ),
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BIGINT ( 0x1c, 0x92 ) );
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BIGINT ( 0x1c, 0x92 ), 0 );
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bigint_subtract_ok ( BIGINT ( 0x9c, 0x30, 0xbf ),
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BIGINT ( 0xde, 0x4e, 0x07 ),
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BIGINT ( 0x42, 0x1d, 0x48 ) );
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BIGINT ( 0x42, 0x1d, 0x48 ), 0 );
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bigint_subtract_ok ( BIGINT ( 0xbb, 0x77, 0x32, 0x5a ),
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BIGINT ( 0x5a, 0xd5, 0xfe, 0x28 ),
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BIGINT ( 0x9f, 0x5e, 0xcb, 0xce ) );
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BIGINT ( 0x9f, 0x5e, 0xcb, 0xce ), 1 );
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bigint_subtract_ok ( BIGINT ( 0x00, 0x00, 0xff, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff ),
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@@ -823,7 +845,7 @@ static void bigint_test_exec ( void ) {
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0x00, 0x00, 0x00, 0x00, 0x00, 0x2a ),
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BIGINT ( 0xff, 0xff, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x2b ) );
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0x00, 0x00, 0x00, 0x00, 0x00, 0x2b ), 1 );
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bigint_subtract_ok ( BIGINT ( 0x7b, 0xaa, 0x16, 0xcf, 0x15, 0x87,
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0xe0, 0x4f, 0x2c, 0xa3, 0xec, 0x2f,
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0x46, 0xfb, 0x83, 0xc6, 0xe0, 0xee,
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@@ -835,7 +857,7 @@ static void bigint_test_exec ( void ) {
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BIGINT ( 0xca, 0xab, 0x9f, 0x54, 0x4e, 0x48,
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0x75, 0x8c, 0x63, 0x28, 0x69, 0x78,
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0xe8, 0x8a, 0x3d, 0xd8, 0x4b, 0x24,
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0xb8, 0xa4, 0x71, 0x6d, 0x6b ) );
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0xb8, 0xa4, 0x71, 0x6d, 0x6b ), 1 );
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bigint_subtract_ok ( BIGINT ( 0x5b, 0x06, 0x77, 0x7b, 0xfd, 0x34,
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0x5f, 0x0f, 0xd9, 0xbd, 0x8e, 0x5d,
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0xc8, 0x4a, 0x70, 0x95, 0x1b, 0xb6,
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@@ -901,7 +923,7 @@ static void bigint_test_exec ( void ) {
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0x29, 0x8c, 0x43, 0x9f, 0xf0, 0x9d,
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0xda, 0xc8, 0x8c, 0x71, 0x86, 0x97,
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0x7f, 0xcb, 0x94, 0x31, 0x1d, 0xbc,
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0x44, 0x1a ) );
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0x44, 0x1a ), 0 );
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bigint_shl_ok ( BIGINT ( 0xe0 ),
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BIGINT ( 0xc0 ) );
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bigint_shl_ok ( BIGINT ( 0x43, 0x1d ),
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