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Adapt key checking functions for Curve25519

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This commit is contained in:
Manuel Pégourié-Gonnard 2013-12-04 11:08:01 +01:00
parent 661536677b
commit 312d2e8ea2
4 changed files with 125 additions and 19 deletions
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58
library/ecp.c
View file

@ -176,6 +176,14 @@ const ecp_curve_info *ecp_curve_info_from_name( const char *name )
return( NULL );
}
/*
* Tell if a group structure is associated to a Montgomery curve
*/
static inline int ecp_is_montgomery( const ecp_group *grp )
{
return( grp->G.X.p != NULL && grp->G.Y.p == NULL );
}
/*
* Initialize (the components of) a point
*/
@ -1498,22 +1506,31 @@ cleanup:
}
/*
* Check that a point is valid as a public key (SEC1 3.2.3.1)
* Check that a point is valid as a public key
*/
int ecp_check_pubkey( const ecp_group *grp, const ecp_point *pt )
{
int ret;
mpi YY, RHS;
if( mpi_cmp_int( &pt->Z, 0 ) == 0 )
return( POLARSSL_ERR_ECP_INVALID_KEY );
/*
* pt coordinates must be normalized for our checks
*/
/* Must use affine coordinates */
if( mpi_cmp_int( &pt->Z, 1 ) != 0 )
return( POLARSSL_ERR_ECP_INVALID_KEY );
if( ecp_is_montgomery( grp ) )
{
/* Just check X is the correct number of bytes */
if( mpi_size( &pt->X ) > ( grp->nbits + 7 ) / 8 )
return( POLARSSL_ERR_ECP_INVALID_KEY );
return( 0 );
}
/*
* Ok, so we have a short Weierstrass curve as in SEC1 3.2.3.1
*/
/* pt coordinates must be normalized for our checks */
if( mpi_cmp_int( &pt->X, 0 ) < 0 ||
mpi_cmp_int( &pt->Y, 0 ) < 0 ||
mpi_cmp_mpi( &pt->X, &grp->P ) >= 0 ||
@ -1522,6 +1539,12 @@ int ecp_check_pubkey( const ecp_group *grp, const ecp_point *pt )
mpi_init( &YY ); mpi_init( &RHS );
if( mpi_cmp_int( &pt->X, 0 ) < 0 ||
mpi_cmp_int( &pt->Y, 0 ) < 0 ||
mpi_cmp_mpi( &pt->X, &grp->P ) >= 0 ||
mpi_cmp_mpi( &pt->Y, &grp->P ) >= 0 )
return( POLARSSL_ERR_ECP_INVALID_KEY );
/*
* YY = Y^2
* RHS = X (X^2 + A) + B = X^3 + A X + B
@ -1543,13 +1566,26 @@ cleanup:
}
/*
* Check that an mpi is valid as a private key (SEC1 3.2)
* Check that an mpi is valid as a private key
*/
int ecp_check_privkey( const ecp_group *grp, const mpi *d )
{
/* We want 1 <= d <= N-1 */
if ( mpi_cmp_int( d, 1 ) < 0 || mpi_cmp_mpi( d, &grp->N ) >= 0 )
return( POLARSSL_ERR_ECP_INVALID_KEY );
if( ecp_is_montgomery( grp ) )
{
/* see the Curve25519 paper */
if( mpi_get_bit( d, 0 ) != 0 ||
mpi_get_bit( d, 1 ) != 0 ||
mpi_get_bit( d, 2 ) != 0 ||
mpi_msb( d ) - 1 != grp->nbits ) /* mpi_msb is one-based! */
return( POLARSSL_ERR_ECP_INVALID_KEY );
}
else
{
/* see SEC1 3.2 */
if( mpi_cmp_int( d, 1 ) < 0 ||
mpi_cmp_mpi( d, &grp->N ) >= 0 )
return( POLARSSL_ERR_ECP_INVALID_KEY );
}
return( 0 );
}

6
library/ecp_curves.c
View file

@ -357,6 +357,12 @@ static int ecp_use_curve25519( ecp_group *grp )
MPI_CHK( mpi_sub_int( &grp->P, &grp->P, 19 ) );
grp->pbits = mpi_msb( &grp->P );
/* Y intentionaly not set, since we use x/z coordinates.
* This is used as a marker to identify Montgomery curves! */
MPI_CHK( mpi_lset( &grp->G.X, 9 ) );
MPI_CHK( mpi_lset( &grp->G.Z, 1 ) );
mpi_free( &grp->G.Y );
/* Actually, the required msb for private keys */
grp->nbits = 254;

50
tests/suites/test_suite_ecp.data
View file

@ -159,6 +159,12 @@ ecp_small_check_pub:0:2:1:0
ECP small check pubkey #10
ecp_small_check_pub:10:25:1:POLARSSL_ERR_ECP_INVALID_KEY
ECP check pubkey Montgomery #1 (too big)
ecp_check_pub_mx:POLARSSL_ECP_DP_M255:"010000000000000000000000000000000000000000000000000000000000000000":POLARSSL_ERR_ECP_INVALID_KEY
ECP check pubkey Montgomery #2 (biggest)
ecp_check_pub_mx:POLARSSL_ECP_DP_M255:"FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF":0
ECP write binary #0 (zero, bad format)
depends_on:POLARSSL_ECP_DP_SECP192R1_ENABLED
ecp_write_binary:POLARSSL_ECP_DP_SECP192R1:"01":"01":"00":POLARSSL_ECP_PF_UNKNOWN:"00":1:POLARSSL_ERR_ECP_BAD_INPUT_DATA
@ -271,9 +277,49 @@ ECP tls write-read group #2
depends_on:POLARSSL_ECP_DP_SECP521R1_ENABLED
ecp_tls_write_read_group:POLARSSL_ECP_DP_SECP521R1
ECP check privkey
ECP check privkey #1 (short weierstrass, too small)
depends_on:POLARSSL_ECP_DP_SECP192R1_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_SECP192R1
ecp_check_privkey:POLARSSL_ECP_DP_SECP192R1:"00":POLARSSL_ERR_ECP_INVALID_KEY
ECP check privkey #2 (short weierstrass, smallest)
depends_on:POLARSSL_ECP_DP_SECP192R1_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_SECP192R1:"01":0
ECP check privkey #3 (short weierstrass, biggest)
depends_on:POLARSSL_ECP_DP_SECP192R1_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_SECP192R1:"FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22830":0
ECP check privkey #4 (short weierstrass, too big)
depends_on:POLARSSL_ECP_DP_SECP192R1_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_SECP192R1:"FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22831":POLARSSL_ERR_ECP_INVALID_KEY
ECP check privkey #5 (montgomery, too big)
depends_on:POLARSSL_ECP_DP_M255_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_M255:"C000000000000000000000000000000000000000000000000000000000000000":POLARSSL_ERR_ECP_INVALID_KEY
ECP check privkey #6 (montgomery, not big enough)
depends_on:POLARSSL_ECP_DP_M255_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_M255:"3FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF0":POLARSSL_ERR_ECP_INVALID_KEY
ECP check privkey #7 (montgomery, msb OK)
depends_on:POLARSSL_ECP_DP_M255_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_M255:"4000000000000000000000000000000000000000000000000000000000000000":0
ECP check privkey #8 (montgomery, bit 0 set)
depends_on:POLARSSL_ECP_DP_M255_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_M255:"4000000000000000000000000000000000000000000000000000000000000001":POLARSSL_ERR_ECP_INVALID_KEY
ECP check privkey #9 (montgomery, bit 1 set)
depends_on:POLARSSL_ECP_DP_M255_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_M255:"4000000000000000000000000000000000000000000000000000000000000002":POLARSSL_ERR_ECP_INVALID_KEY
ECP check privkey #10 (montgomery, bit 2 set)
depends_on:POLARSSL_ECP_DP_M255_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_M255:"4000000000000000000000000000000000000000000000000000000000000004":POLARSSL_ERR_ECP_INVALID_KEY
ECP check privkey #11 (montgomery, OK)
depends_on:POLARSSL_ECP_DP_M255_ENABLED
ecp_check_privkey:POLARSSL_ECP_DP_M255:"7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF8":0
ECP gen keypair
depends_on:POLARSSL_ECP_DP_SECP192R1_ENABLED

30
tests/suites/test_suite_ecp.function
View file

@ -188,6 +188,27 @@ void ecp_small_check_pub( int x, int y, int z, int ret )
}
/* END_CASE */
/* BEGIN_CASE */
void ecp_check_pub_mx( int grp_id, char *key_hex, int ret )
{
ecp_group grp;
ecp_point P;
ecp_group_init( &grp );
ecp_point_init( &P );
TEST_ASSERT( ecp_use_known_dp( &grp, grp_id ) == 0 );
TEST_ASSERT( mpi_read_string( &P.X, 16, key_hex ) == 0 );
TEST_ASSERT( mpi_lset( &P.Z, 1 ) == 0 );
TEST_ASSERT( ecp_check_pubkey( &grp, &P ) == ret );
ecp_group_free( &grp );
ecp_point_free( &P );
}
/* END_CASE */
/* BEGIN_CASE */
void ecp_test_vect( int id, char *dA_str, char *xA_str, char *yA_str,
char *dB_str, char *xB_str, char *yB_str, char *xZ_str,
@ -490,7 +511,7 @@ void ecp_tls_write_read_group( int id )
/* END_CASE */
/* BEGIN_CASE */
void ecp_check_privkey( int id )
void ecp_check_privkey( int id, char *key_hex, int ret )
{
ecp_group grp;
mpi d;
@ -499,12 +520,9 @@ void ecp_check_privkey( int id )
mpi_init( &d );
TEST_ASSERT( ecp_use_known_dp( &grp, id ) == 0 );
TEST_ASSERT( mpi_read_string( &d, 16, key_hex ) == 0 );
TEST_ASSERT( mpi_lset( &d, 0 ) == 0 );
TEST_ASSERT( ecp_check_privkey( &grp, &d ) == POLARSSL_ERR_ECP_INVALID_KEY );
TEST_ASSERT( mpi_copy( &d, &grp.N ) == 0 );
TEST_ASSERT( ecp_check_privkey( &grp, &d ) == POLARSSL_ERR_ECP_INVALID_KEY );
TEST_ASSERT( ecp_check_privkey( &grp, &d ) == ret );
ecp_group_free( &grp );
mpi_free( &d );