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Implement parsing SpecifiedECParameters

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This commit is contained in:
Manuel Pégourié-Gonnard 2014-03-14 17:58:42 +01:00
parent 6c1f69b879
commit eab20d2a9c
2 changed files with 294 additions and 11 deletions
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9
include/polarssl/oid.h
View file

@ -315,6 +315,15 @@
/* brainpoolP512r1 OBJECT IDENTIFIER ::= {versionOne 13} */
#define OID_EC_GRP_BP512R1 OID_EC_BRAINPOOL_V1 "\x0D"
/*
* SEC1 C.1
*
* prime-field OBJECT IDENTIFIER ::= { id-fieldType 1 }
* id-fieldType OBJECT IDENTIFIER ::= { ansi-X9-62 fieldType(1)}
*/
#define OID_ANSI_X9_62_FIELD_TYPE OID_ANSI_X9_62 "\x01"
#define OID_ANSI_X9_62_PRIME_FIELD OID_ANSI_X9_62_FIELD_TYPE "\x01"
/*
* ECDSA signature identifers, from RFC 5480
*/

290
library/pkparse.c
View file

@ -148,12 +148,12 @@ int pk_parse_public_keyfile( pk_context *ctx, const char *path )
#endif /* POLARSSL_FS_IO */
#if defined(POLARSSL_ECP_C)
/* Get an EC group id from an ECParameters buffer
/* Minimally parse an ECParameters buffer to and asn1_buf
*
* ECParameters ::= CHOICE {
* namedCurve OBJECT IDENTIFIER
* specifiedCurve SpecifiedECDomain -- = SEQUENCE { ... }
* -- implicitCurve NULL
* -- specifiedCurve SpecifiedECDomain
* }
*/
static int pk_get_ecparams( unsigned char **p, const unsigned char *end,
@ -161,10 +161,19 @@ static int pk_get_ecparams( unsigned char **p, const unsigned char *end,
{
int ret;
/* Tag may be either OID or SEQUENCE */
params->tag = **p;
if( params->tag != ASN1_OID &&
params->tag != ( ASN1_CONSTRUCTED | ASN1_SEQUENCE ) )
{
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT +
POLARSSL_ERR_ASN1_UNEXPECTED_TAG );
}
if( ( ret = asn1_get_tag( p, end, &params->len, ASN1_OID ) ) != 0 )
if( ( ret = asn1_get_tag( p, end, &params->len, params->tag ) ) != 0 )
{
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
}
params->p = *p;
*p += params->len;
@ -176,16 +185,277 @@ static int pk_get_ecparams( unsigned char **p, const unsigned char *end,
return( 0 );
}
/*
* Import a point from unsigned binary data (SEC1 2.3.4), sloppy version:
* accepts compressed point, but then don't fill the Y coordinate, only its
* parity bit. This is a hack to be able to read SpecifiedECDomain to the
* degree that we can check if it is one of the known groups,
* see pk_group_from_specified() and ultimately pk_group_id_from_specified().
*/
static int pk_ecp_point_read_sloppy( const ecp_group *grp, ecp_point *pt,
const unsigned char *buf, size_t ilen )
{
int ret;
size_t plen;
if( ilen == 1 && buf[0] == 0x00 )
return( ecp_set_zero( pt ) );
plen = mpi_size( &grp->P );
if( ilen == 2 * plen + 1 && buf[0] == 0x04 )
{
MPI_CHK( mpi_read_binary( &pt->X, buf + 1, plen ) );
MPI_CHK( mpi_read_binary( &pt->Y, buf + 1 + plen, plen ) );
MPI_CHK( mpi_lset( &pt->Z, 1 ) );
}
else if( ilen == plen + 1 && ( buf[0] == 0x02 || buf[0] == 0x03 ) )
{
MPI_CHK( mpi_read_binary( &pt->X, buf + 1, plen ) );
MPI_CHK( mpi_lset( &pt->Y, buf[0] - 2 ) );
MPI_CHK( mpi_lset( &pt->Z, 1 ) );
}
else
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
cleanup:
return( ret );
}
/*
* Parse a SpecifiedECDomain (SEC 1 C.2) and (mostly) fill the group with it.
* WARNING: the resulting group should only be used with
* pk_group_id_from_specified(), since its base point may not be set correctly
* if it was encoded compressed.
*
* SpecifiedECDomain ::= SEQUENCE {
* version SpecifiedECDomainVersion(ecdpVer1 | ecdpVer2 | ecdpVer3, ...),
* fieldID FieldID {{FieldTypes}},
* curve Curve,
* base ECPoint,
* order INTEGER,
* cofactor INTEGER OPTIONAL,
* hash HashAlgorithm OPTIONAL,
* ...
* }
*
* We only support prime-field as field type, and ignore hash and cofactor.
*/
static int pk_group_from_specified( const asn1_buf *params, ecp_group *grp )
{
int ret;
unsigned char *p = params->p;
const unsigned char * const end = params->p + params->len;
const unsigned char *end_field, *end_curve;
size_t len;
int ver;
/* SpecifiedECDomainVersion ::= INTEGER { 1, 2, 3 } */
if( ( ret = asn1_get_int( &p, end, &ver ) ) != 0 )
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
if( ver < 1 || ver > 3 )
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT );
/*
* FieldID { FIELD-ID:IOSet } ::= SEQUENCE { -- Finite field
* fieldType FIELD-ID.&id({IOSet}),
* parameters FIELD-ID.&Type({IOSet}{@fieldType})
* }
*/
if( ( ret = asn1_get_tag( &p, end, &len,
ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
return( ret );
end_field = p + len;
/*
* FIELD-ID ::= TYPE-IDENTIFIER
* FieldTypes FIELD-ID ::= {
* { Prime-p IDENTIFIED BY prime-field } |
* { Characteristic-two IDENTIFIED BY characteristic-two-field }
* }
* prime-field OBJECT IDENTIFIER ::= { id-fieldType 1 }
*/
if( ( ret = asn1_get_tag( &p, end_field, &len, ASN1_OID ) ) != 0 )
return( ret );
if( len != OID_SIZE( OID_ANSI_X9_62_PRIME_FIELD ) ||
memcmp( p, OID_ANSI_X9_62_PRIME_FIELD, len ) != 0 )
{
return( POLARSSL_ERR_PK_FEATURE_UNAVAILABLE );
}
p += len;
/* Prime-p ::= INTEGER -- Field of size p. */
if( ( ret = asn1_get_mpi( &p, end_field, &grp->P ) ) != 0 )
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
grp->pbits = mpi_msb( &grp->P );
if( p != end_field )
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT +
POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
/*
* Curve ::= SEQUENCE {
* a FieldElement,
* b FieldElement,
* seed BIT STRING OPTIONAL
* -- Shall be present if used in SpecifiedECDomain
* -- with version equal to ecdpVer2 or ecdpVer3
* }
*/
if( ( ret = asn1_get_tag( &p, end, &len,
ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
return( ret );
end_curve = p + len;
/*
* FieldElement ::= OCTET STRING
* containing an integer in the case of a prime field
*/
if( ( ret = asn1_get_tag( &p, end_curve, &len, ASN1_OCTET_STRING ) ) != 0 ||
( ret = mpi_read_binary( &grp->A, p, len ) ) != 0 )
{
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
}
p += len;
if( ( ret = asn1_get_tag( &p, end_curve, &len, ASN1_OCTET_STRING ) ) != 0 ||
( ret = mpi_read_binary( &grp->B, p, len ) ) != 0 )
{
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
}
p += len;
/* Ignore seed BIT STRING OPTIONAL */
if( ( ret = asn1_get_tag( &p, end_curve, &len, ASN1_BIT_STRING ) ) == 0 )
p += len;
if( p != end_curve )
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT +
POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
/*
* ECPoint ::= OCTET STRING
*/
if( ( ret = asn1_get_tag( &p, end, &len, ASN1_OCTET_STRING ) ) != 0 ||
( ret = pk_ecp_point_read_sloppy( grp, &grp->G,
( const unsigned char *) p, len ) ) != 0 )
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
p += len;
/*
* order INTEGER
*/
if( ( ret = asn1_get_mpi( &p, end, &grp->N ) ) )
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
grp->nbits = mpi_msb( &grp->N );
/*
* Allow optional elements by purposefully not enforcing p == end here.
*/
return( 0 );
}
/*
* Find the group id associated with an (almost filled) group as generated by
* pk_group_from_specified(), or return an error if unknown.
*/
static int pk_group_id_from_group( const ecp_group *grp, ecp_group_id *grp_id )
{
int ret;
ecp_group ref;
const ecp_group_id *id;
ecp_group_init( &ref );
for( id = ecp_grp_id_list(); *id != POLARSSL_ECP_DP_NONE; id++ )
{
/* Load the group associated to that id */
ecp_group_free( &ref );
MPI_CHK( ecp_use_known_dp( &ref, *id ) );
/* Compare to the group we were given, starting with easy tests */
if( grp->pbits == ref.pbits && grp->nbits == ref.nbits &&
mpi_cmp_mpi( &grp->P, &ref.P ) == 0 &&
mpi_cmp_mpi( &grp->A, &ref.A ) == 0 &&
mpi_cmp_mpi( &grp->B, &ref.B ) == 0 &&
mpi_cmp_mpi( &grp->N, &ref.N ) == 0 &&
mpi_cmp_mpi( &grp->G.X, &ref.G.X ) == 0 &&
mpi_cmp_mpi( &grp->G.Z, &ref.G.Z ) == 0 &&
/* For Y we may only know the parity bit, so compare only that */
mpi_get_bit( &grp->G.Y, 0 ) == mpi_get_bit( &ref.G.Y, 0 ) )
{
break;
}
}
cleanup:
ecp_group_free( &ref );
*grp_id = *id;
if( ret == 0 && *id == POLARSSL_ECP_DP_NONE )
ret = POLARSSL_ERR_ECP_FEATURE_UNAVAILABLE;
return( ret );
}
/*
* Parse a SpecifiedECDomain (SEC 1 C.2) and find the associated group ID
*/
static int pk_group_id_from_specified( const asn1_buf *params,
ecp_group_id *grp_id )
{
int ret;
ecp_group grp;
ecp_group_init( &grp );
if( ( ret = pk_group_from_specified( params, &grp ) ) != 0 )
goto cleanup;
ret = pk_group_id_from_group( &grp, grp_id );
cleanup:
ecp_group_free( &grp );
return( ret );
}
/*
* Use EC parameters to initialise an EC group
*
* ECParameters ::= CHOICE {
* namedCurve OBJECT IDENTIFIER
* specifiedCurve SpecifiedECDomain -- = SEQUENCE { ... }
* -- implicitCurve NULL
*/
static int pk_use_ecparams( const asn1_buf *params, ecp_group *grp )
{
int ret;
ecp_group_id grp_id;
if( params->tag == ASN1_OID )
{
if( oid_get_ec_grp( params, &grp_id ) != 0 )
return( POLARSSL_ERR_PK_UNKNOWN_NAMED_CURVE );
}
else
{
if( ( ret = pk_group_id_from_specified( params, &grp_id ) ) != 0 )
return( ret );
}
/*
* grp may already be initilialized; if so, make sure IDs match
@ -451,7 +721,7 @@ static int pk_parse_key_sec1_der( ecp_keypair *eck,
size_t keylen )
{
int ret;
int version;
int version, pubkey_done;
size_t len;
asn1_buf params;
unsigned char *p = (unsigned char *) key;
@ -513,8 +783,10 @@ static int pk_parse_key_sec1_der( ecp_keypair *eck,
}
/*
* Is 'publickey' present? If not, create it from the private key.
* Is 'publickey' present? If not, or if we can't read it (eg because it
* is compressed), create it from the private key.
*/
pubkey_done = 0;
if( ( ret = asn1_get_tag( &p, end, &len,
ASN1_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED | 1 ) ) == 0 )
{
@ -527,15 +799,17 @@ static int pk_parse_key_sec1_der( ecp_keypair *eck,
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT +
POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
if( ( ret = pk_get_ecpubkey( &p, end2, eck ) ) != 0 )
return( ret );
if( ( ret = pk_get_ecpubkey( &p, end2, eck ) ) == 0 )
pubkey_done = 1;
}
else if ( ret != POLARSSL_ERR_ASN1_UNEXPECTED_TAG )
{
ecp_keypair_free( eck );
return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
}
else if( ( ret = ecp_mul( &eck->grp, &eck->Q, &eck->d, &eck->grp.G,
if( ! pubkey_done &&
( ret = ecp_mul( &eck->grp, &eck->Q, &eck->d, &eck->grp.G,
NULL, NULL ) ) != 0 )
{
ecp_keypair_free( eck );