From 0079405918f3a0b096fe48fd9a2b6bf41815bcfb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?= Date: Sat, 9 Feb 2013 19:00:07 +0100 Subject: [PATCH] Add functions for read/write ECPoint records --- include/polarssl/ecp.h | 48 ++++++++++++++++++++++++++++++++------ library/ecp.c | 53 ++++++++++++++++++++++++++++++++++++++---- 2 files changed, 89 insertions(+), 12 deletions(-) diff --git a/include/polarssl/ecp.h b/include/polarssl/ecp.h index 6c1463637..59afd63c0 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 @@ ecp_group; #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 @@ int ecp_group_read_string( ecp_group *grp, int radix, * \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_read_binary( const ecp_group *grp, ecp_point *P, int format, 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 @@ -296,6 +299,37 @@ 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 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 * diff --git a/library/ecp.c b/library/ecp.c index 0a27df2be..b6c50f6a3 100644 --- a/library/ecp.c +++ b/library/ecp.c @@ -186,14 +186,14 @@ cleanup: * 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 @@ int ecp_write_binary( const ecp_group *grp, const ecp_point *P, int format, 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 @@ int ecp_write_binary( const ecp_group *grp, const ecp_point *P, int format, *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 @@ int ecp_write_binary( const ecp_group *grp, const ecp_point *P, int format, *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 ) ); @@ -264,6 +264,49 @@ cleanup: return( ret ); } +/* + * 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.