Merged support for parsing EC keys that use SpecifiedECDomain
diff --git a/ChangeLog b/ChangeLog
index 79ffb76..6c285aa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,7 @@
(POLARSSL_ENTROPY_FORCE_SHA256)
* Testing script ssl-opt.sh added for testing 'live' ssl option
interoperability against OpenSSL and PolarSSL
+ * Support for reading EC keys that use SpecifiedECDomain in some cases.
Changes
* Deprecated the Memory layer
diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index c070df2..decfc73 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -588,6 +588,20 @@
#define POLARSSL_KEY_EXCHANGE_ECDH_RSA_ENABLED
/**
+ * \def POLARSSL_PK_PARSE_EC_EXTENDED
+ *
+ * Enhance support for reading EC keys using variants of SEC1 not allowed by
+ * RFC 5915 and RFC 5480.
+ *
+ * Currently this means parsing the SpecifiedECDomain choice of EC
+ * parameters (only known groups are supported, not arbitrary domains, to
+ * avoid validation issues).
+ *
+ * Disable if you only need to support RFC 5915 + 5480 key formats.
+ */
+#define POLARSSL_PK_PARSE_EC_EXTENDED
+
+/**
* \def POLARSSL_ERROR_STRERROR_BC
*
* Make available the backward compatible error_strerror() next to the
diff --git a/include/polarssl/ecp.h b/include/polarssl/ecp.h
index b35b0d1..61d6a1d 100644
--- a/include/polarssl/ecp.h
+++ b/include/polarssl/ecp.h
@@ -376,8 +376,10 @@
* \param ilen Actual length of input
*
* \return 0 if successful,
- * POLARSSL_ERR_ECP_BAD_INPUT_DATA if input is invalid
- * POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
+ * POLARSSL_ERR_ECP_BAD_INPUT_DATA if input is invalid,
+ * POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed,
+ * POLARSSL_ERR_ECP_FEATURE_UNAVAILABLE if the point format
+ * is not implemented.
*
* \note This function does NOT check that the point actually
* belongs to the given group, see ecp_check_pubkey() for
diff --git a/include/polarssl/oid.h b/include/polarssl/oid.h
index f000b8e..2470d5e 100644
--- a/include/polarssl/oid.h
+++ b/include/polarssl/oid.h
@@ -316,6 +316,15 @@
#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
*/
#define OID_ANSI_X9_62_SIG OID_ANSI_X9_62 "\x04" /* signatures(4) */
diff --git a/library/ecp.c b/library/ecp.c
index f4f2d1c..7cfb44f 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -478,7 +478,8 @@
* Import a point from unsigned binary data (SEC1 2.3.4)
*/
int ecp_point_read_binary( const ecp_group *grp, ecp_point *pt,
- const unsigned char *buf, size_t ilen ) {
+ const unsigned char *buf, size_t ilen )
+{
int ret;
size_t plen;
@@ -487,7 +488,10 @@
plen = mpi_size( &grp->P );
- if( ilen != 2 * plen + 1 || buf[0] != 0x04 )
+ if( buf[0] != 0x04 )
+ return( POLARSSL_ERR_ECP_FEATURE_UNAVAILABLE );
+
+ if( ilen != 2 * plen + 1 )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
MPI_CHK( mpi_read_binary( &pt->X, buf + 1, plen ) );
diff --git a/library/pkparse.c b/library/pkparse.c
index dcb0f3f..4e9e400 100644
--- a/library/pkparse.c
+++ b/library/pkparse.c
@@ -148,12 +148,12 @@
#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 +161,22 @@
{
int ret;
+ /* Tag may be either OID or SEQUENCE */
params->tag = **p;
+ if( params->tag != ASN1_OID
+#if defined(POLARSSL_PK_PARSE_EC_EXTENDED)
+ && params->tag != ( ASN1_CONSTRUCTED | ASN1_SEQUENCE )
+#endif
+ )
+ {
+ 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 +188,262 @@
return( 0 );
}
+#if defined(POLARSSL_PK_PARSE_EC_EXTENDED)
+/*
+ * 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 )
+ return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
+
+ if( ( ret = ecp_point_read_binary( grp, &grp->G,
+ ( const unsigned char *) p, len ) ) != 0 )
+ {
+ /*
+ * If we can't read the point because it's compressed, cheat by
+ * reading only the X coordinate and the parity bit of Y.
+ */
+ if( ret != POLARSSL_ERR_ECP_FEATURE_UNAVAILABLE ||
+ ( p[0] != 0x02 && p[0] != 0x03 ) ||
+ len != mpi_size( &grp->P ) + 1 ||
+ mpi_read_binary( &grp->G.X, p + 1, len - 1 ) != 0 ||
+ mpi_lset( &grp->G.Y, p[0] - 2 ) != 0 ||
+ mpi_lset( &grp->G.Z, 1 ) != 0 )
+ {
+ return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT );
+ }
+ }
+
+ 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 );
+}
+#endif /* POLARSSL_PK_PARSE_EC_EXTENDED */
+
/*
* 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 defined(POLARSSL_PK_PARSE_EC_EXTENDED)
+ if( ( ret = pk_group_id_from_specified( params, &grp_id ) ) != 0 )
+ return( ret );
+#else
+ return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT );
+#endif
+ }
/*
* grp may already be initilialized; if so, make sure IDs match
@@ -201,6 +459,10 @@
/*
* EC public key is an EC point
+ *
+ * The caller is responsible for clearing the structure upon failure if
+ * desired. Take care to pass along the possible ECP_FEATURE_UNAVAILABLE
+ * return code of ecp_point_read_binary() and leave p in a usable state.
*/
static int pk_get_ecpubkey( unsigned char **p, const unsigned char *end,
ecp_keypair *key )
@@ -208,19 +470,17 @@
int ret;
if( ( ret = ecp_point_read_binary( &key->grp, &key->Q,
- (const unsigned char *) *p, end - *p ) ) != 0 ||
- ( ret = ecp_check_pubkey( &key->grp, &key->Q ) ) != 0 )
+ (const unsigned char *) *p, end - *p ) ) == 0 )
{
- ecp_keypair_free( key );
- return( POLARSSL_ERR_PK_INVALID_PUBKEY );
+ ret = ecp_check_pubkey( &key->grp, &key->Q );
}
/*
- * We know ecp_point_read_binary consumed all bytes
+ * We know ecp_point_read_binary consumed all bytes or failed
*/
*p = (unsigned char *) end;
- return( 0 );
+ return( ret );
}
#endif /* POLARSSL_ECP_C */
@@ -451,7 +711,7 @@
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 +773,10 @@
}
/*
- * 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 +789,27 @@
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
+ {
+ /*
+ * The only acceptable failure mode of pk_get_ecpubkey() above
+ * is if the point format is not recognized.
+ */
+ if( ret != POLARSSL_ERR_ECP_FEATURE_UNAVAILABLE )
+ return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT );
+ }
}
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 );
diff --git a/tests/data_files/ec_prv.specdom.der b/tests/data_files/ec_prv.specdom.der
new file mode 100644
index 0000000..a80a2e3
--- /dev/null
+++ b/tests/data_files/ec_prv.specdom.der
Binary files differ
diff --git a/tests/suites/test_suite_pkparse.data b/tests/suites/test_suite_pkparse.data
index dc13fdb..b502017 100644
--- a/tests/suites/test_suite_pkparse.data
+++ b/tests/suites/test_suite_pkparse.data
@@ -198,6 +198,10 @@
depends_on:POLARSSL_PEM_PARSE_C:POLARSSL_ECP_C:POLARSSL_ECP_DP_BP512R1_ENABLED
pk_parse_keyfile_ec:"data_files/ec_bp512_prv.pem":"NULL":0
+Parse EC Key #15 (SEC1 DER, secp256k1, SpecifiedECDomain)
+depends_on:POLARSSL_PEM_PARSE_C:POLARSSL_ECP_C:POLARSSL_ECP_DP_SECP256K1_ENABLED:POLARSSL_PK_PARSE_EC_EXTENDED
+pk_parse_keyfile_ec:"data_files/ec_prv.specdom.der":"NULL":0
+
Key ASN1 (Incorrect first tag)
pk_parse_key_rsa:"":"":POLARSSL_ERR_PK_KEY_INVALID_FORMAT