Commit b325887f authored by Manuel Pégourié-Gonnard's avatar Manuel Pégourié-Gonnard
Browse files

Add ecp_tls_write_group()

parent 6282acae
......@@ -53,6 +53,11 @@ typedef struct
}
ecp_point;
/*
* RFC 4492 defines an enum NamedCurve with two-bytes values
*/
typedef uint16_t ecp_group_id;
/**
* \brief ECP group structure
*
......@@ -70,6 +75,7 @@ ecp_point;
*/
typedef struct
{
ecp_group_id id; /*!< RFC 4492 group ID */
mpi P; /*!< prime modulus of the base field */
mpi B; /*!< constant term in the equation */
ecp_point G; /*!< generator of the subgroup used */
......@@ -284,7 +290,7 @@ int ecp_point_read_binary( const ecp_group *grp, ecp_point *P,
* \note Index should be a value of RFC 4492's enum NamdeCurve,
* possibly in the form of a POLARSSL_ECP_DP_XXX macro.
*/
int ecp_use_known_dp( ecp_group *grp, uint16_t index );
int ecp_use_known_dp( ecp_group *grp, ecp_group_id id );
/**
* \brief Set a group from a TLS ECParameters record
......@@ -299,6 +305,20 @@ int ecp_use_known_dp( ecp_group *grp, uint16_t index );
*/
int ecp_tls_read_group( ecp_group *grp, const unsigned char *buf, size_t len );
/**
* \brief Write the TLS ECParameters record for a group
*
* \param grp ECP group used
* \param olen Number of bytes actually written
* \param buf Buffer to write to
* \param blen Buffer length
*
* \return 0 if successful,
* or POLARSSL_ERR_ECP_BUFFER_TOO_SMALL
*/
int ecp_tls_write_group( const ecp_group *grp, size_t *olen,
unsigned char *buf, size_t blen );
/**
* \brief Import a point from a TLS ECPoint record
*
......
......@@ -534,9 +534,11 @@ cleanup:
/*
* Set a group using well-known domain parameters
*/
int ecp_use_known_dp( ecp_group *grp, uint16_t index )
int ecp_use_known_dp( ecp_group *grp, ecp_group_id id )
{
switch( index )
grp->id = id;
switch( id )
{
case POLARSSL_ECP_DP_SECP192R1:
grp->modp = ecp_mod_p192;
......@@ -574,7 +576,7 @@ int ecp_use_known_dp( ecp_group *grp, uint16_t index )
*/
int ecp_tls_read_group( ecp_group *grp, const unsigned char *buf, size_t len )
{
uint16_t namedcurve;
ecp_group_id id;
/*
* We expect at least three bytes (see below)
......@@ -589,10 +591,37 @@ int ecp_tls_read_group( ecp_group *grp, const unsigned char *buf, size_t len )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
/*
* Next two bytes are the namedcurve
* Next two bytes are the namedcurve value
*/
id = 256 * buf[0] + buf[1];
return ecp_use_known_dp( grp, id );
}
/*
* Write the ECParameters record corresponding to a group (RFC 4492)
*/
int ecp_tls_write_group( const ecp_group *grp, size_t *olen,
unsigned char *buf, size_t blen )
{
/*
* We are going to write 3 bytes (see below)
*/
namedcurve = 256 * buf[0] + buf[1];
return ecp_use_known_dp( grp, namedcurve );
*olen = 3;
if( blen < *olen )
return( POLARSSL_ERR_ECP_BUFFER_TOO_SMALL );
/*
* First byte is curve_type, always named_curve
*/
*buf++ = POLARSSL_ECP_TLS_NAMED_CURVE;
/*
* Next two bytes are the namedcurve value
*/
buf[0] = grp->id >> 8;
buf[1] = grp->id && 0xFF;
return 0;
}
/*
......
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