Add functions for read/write ECPoint records
diff --git a/include/polarssl/ecp.h b/include/polarssl/ecp.h
index 6c14636..59afd63 100644
--- a/include/polarssl/ecp.h
+++ b/include/polarssl/ecp.h
@@ -33,6 +33,7 @@
* ECP error codes
*/
#define POLARSSL_ERR_ECP_BAD_INPUT_DATA -0x4F80 /**< Bad input parameters to function. */
+#define POLARSSL_ERR_ECP_BUFFER_TOO_SMALL -0x4F80 /**< The buffer is too small to write to. */
#define POLARSSL_ERR_ECP_GENERIC -0x4F00 /**< Generic ECP error */
/**
@@ -117,15 +118,15 @@
#define POLARSSL_ECP_WINDOW_SIZE 7 /**< Maximum NAF width used. */
/*
- * Point formats
+ * Point formats, from RFC 4492's enum ECPointFormat
*/
#define POLARSSL_ECP_PF_UNCOMPRESSED 0 /**< Uncompressed point format */
#define POLARSSL_ECP_PF_COMPRESSED 1 /**< Compressed point format */
/*
- * Some constants from RFC 4492 (ECC for TLS)
+ * Some other constants from RFC 4492
*/
-#define POLARSSL_ECP_TLS_NAMED_CURVE 3 /**< ECCurveType named_curve */
+#define POLARSSL_ECP_TLS_NAMED_CURVE 3 /**< ECCurveType's named_curve */
#ifdef __cplusplus
@@ -239,14 +240,16 @@
* \param grp Group to which the point should belong
* \param P Point to export
* \param format Point format, should be a POLARSSL_ECP_PF_XXX macro
- * \param olen Length of the actual ouput
+ * \param olen Length of the actual output
* \param buf Output buffer
* \param buflen Length of the output buffer
*
- * \return 0 if successful, or POLARSSL_ERR_ECP_GENERIC
+ * \return 0 if successful,
+ * or POLARSSL_ERR_ECP_BAD_INPUT_DATA
+ * or POLARSSL_ERR_ECP_BUFFER_TOO_SMALL
*/
int ecp_write_binary( const ecp_group *grp, const ecp_point *P, int format,
- size_t *olen, unsigned char *buf, size_t buflen );
+ uint8_t *olen, unsigned char *buf, size_t buflen );
/**
* \brief Import a point from unsigned binary data
@@ -284,7 +287,7 @@
int ecp_use_known_dp( ecp_group *grp, uint16_t index );
/**
- * \brief Read a group from an ECParameters record
+ * \brief Set a group from a TLS ECParameters record
*
* \param grp Destination group
* \param buf Start of input buffer
@@ -297,6 +300,37 @@
int ecp_tls_read_group( ecp_group *grp, const unsigned char *buf, size_t len );
/**
+ * \brief Import a point from a TLS ECPoint record
+ *
+ * \param grp ECP group used
+ * \param pt Destination point
+ * \param buf Start of input buffer
+ * \param len Buffer length
+ *
+ * \return O if successful,
+ * POLARSSL_ERR_MPI_XXX if initialization failed
+ * POLARSSL_ERR_ECP_BAD_INPUT_DATA if input is invalid
+ */
+int ecp_tls_read_point( const ecp_group *grp, ecp_point *pt,
+ const unsigned char *buf, size_t len );
+
+/**
+ * \brief Export a point as a TLS ECPoint record
+ *
+ * \param grp ECP group used
+ * \param pt Point to export
+ * \param format Export format
+ * \param buf Buffer to write to
+ * \param len Buffer length
+ *
+ * \return 0 if successful,
+ * or POLARSSL_ERR_ECP_BAD_INPUT_DATA
+ * or POLARSSL_ERR_ECP_BUFFER_TOO_SMALL
+ */
+int ecp_tls_write_point( const ecp_group *grp, const ecp_point *pt,
+ int format, unsigned char *buf, size_t buf_len );
+
+/**
* \brief Addition: R = P + Q
*
* \param grp ECP group
diff --git a/library/ecp.c b/library/ecp.c
index 0a27df2..b6c50f6 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -186,14 +186,14 @@
* Export a point into unsigned binary data (SEC1 2.3.3)
*/
int ecp_write_binary( const ecp_group *grp, const ecp_point *P, int format,
- size_t *olen, unsigned char *buf, size_t buflen )
+ uint8_t *olen, unsigned char *buf, size_t buflen )
{
int ret;
size_t plen;
if( format != POLARSSL_ECP_PF_UNCOMPRESSED &&
format != POLARSSL_ECP_PF_COMPRESSED )
- return( POLARSSL_ERR_ECP_GENERIC );
+ return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
/*
* Common case: P == 0
@@ -201,7 +201,7 @@
if( mpi_cmp_int( &P->Z, 0 ) == 0 )
{
if( buflen < 1 )
- return( POLARSSL_ERR_ECP_GENERIC );
+ return( POLARSSL_ERR_ECP_BUFFER_TOO_SMALL );
buf[0] = 0x00;
*olen = 1;
@@ -216,7 +216,7 @@
*olen = 2 * plen + 1;
if( buflen < *olen )
- return( POLARSSL_ERR_ECP_GENERIC );
+ return( POLARSSL_ERR_ECP_BUFFER_TOO_SMALL );
buf[0] = 0x04;
MPI_CHK( mpi_write_binary( &P->X, buf + 1, plen ) );
@@ -227,7 +227,7 @@
*olen = plen + 1;
if( buflen < *olen )
- return( POLARSSL_ERR_ECP_GENERIC );
+ return( POLARSSL_ERR_ECP_BUFFER_TOO_SMALL );
buf[0] = 0x02 + mpi_get_bit( &P->Y, 0 );
MPI_CHK( mpi_write_binary( &P->X, buf + 1, plen ) );
@@ -265,6 +265,49 @@
}
/*
+ * Import a point from a TLS ECPoint record (RFC 4492)
+ * struct {
+ * opaque point <1..2^8-1>;
+ * } ECPoint;
+ */
+int ecp_tls_read_point( const ecp_group *grp, ecp_point *pt,
+ const unsigned char *buf, size_t buf_len )
+{
+ unsigned char data_len;
+
+ /*
+ * We must have at least two bytes (1 for length, at least of for data)
+ */
+ if( buf_len < 2 )
+ return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
+
+ data_len = *buf++;
+ if( data_len < 1 || data_len > buf_len - 1 )
+ return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
+
+ return ecp_read_binary( grp, pt, POLARSSL_ECP_PF_UNCOMPRESSED,
+ buf, data_len );
+}
+
+/*
+ * Export a point as a TLS ECPoint record (RFC 4492)
+ * struct {
+ * opaque point <1..2^8-1>;
+ * } ECPoint;
+ */
+int ecp_tls_write_point( const ecp_group *grp, const ecp_point *pt,
+ int format, unsigned char *buf, size_t buf_len )
+{
+ /*
+ * buf_len must be at least one, for our length byte
+ */
+ if( buf_len < 1 )
+ return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
+
+ return ecp_write_binary( grp, pt, format, buf, buf + 1, buf_len - 1);
+}
+
+/*
* Wrapper around fast quasi-modp functions, with fall-back to mpi_mod_mpi.
* See the documentation of struct ecp_group.
*/