From eab20d2a9c9dac1eefa308e237febde847034e3d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?= Date: Fri, 14 Mar 2014 17:58:42 +0100 Subject: [PATCH] Implement parsing SpecifiedECParameters --- include/polarssl/oid.h | 9 ++ library/pkparse.c | 296 +++++++++++++++++++++++++++++++++++++++-- 2 files changed, 294 insertions(+), 11 deletions(-) diff --git a/include/polarssl/oid.h b/include/polarssl/oid.h index f000b8e7e..2470d5e1d 100644 --- a/include/polarssl/oid.h +++ b/include/polarssl/oid.h @@ -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 */ diff --git a/library/pkparse.c b/library/pkparse.c index dcb0f3f91..19078493d 100644 --- a/library/pkparse.c +++ b/library/pkparse.c @@ -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, ¶ms->len, ASN1_OID ) ) != 0 ) + if( ( ret = asn1_get_tag( p, end, ¶ms->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( oid_get_ec_grp( params, &grp_id ) != 0 ) - return( POLARSSL_ERR_PK_UNKNOWN_NAMED_CURVE ); + 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 ) { @@ -527,16 +799,18 @@ 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, - NULL, NULL ) ) != 0 ) + + if( ! pubkey_done && + ( ret = ecp_mul( &eck->grp, &eck->Q, &eck->d, &eck->grp.G, + NULL, NULL ) ) != 0 ) { ecp_keypair_free( eck ); return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );