Add ecjpake_zpk_read()
Not really tested yet
diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
index e827040..5246c78 100644
--- a/include/mbedtls/ecp.h
+++ b/include/mbedtls/ecp.h
@@ -347,6 +347,21 @@
int mbedtls_ecp_is_zero( mbedtls_ecp_point *pt );
/**
+ * \brief Compare two points
+ *
+ * \note This assumes the points are normalized. Otherwise,
+ * they may compare as "not equal" even if they are.
+ *
+ * \param P First point to compare
+ * \param Q Second point to compare
+ *
+ * \return 0 if the points are equal,
+ * MBEDTLS_ERR_ECP_BAD_INPUT_DATA otherwise
+ */
+int mbedtls_ecp_point_cmp( const mbedtls_ecp_point *P,
+ const mbedtls_ecp_point *Q );
+
+/**
* \brief Import a non-zero point from two ASCII strings
*
* \param P Destination point
diff --git a/library/ecjpake.c b/library/ecjpake.c
index 3046154..328204c 100644
--- a/library/ecjpake.c
+++ b/library/ecjpake.c
@@ -121,7 +121,7 @@
/*
* Generate ZKP (7.4.2.3.2) and write it as ECSchnorrZKP (7.4.2.2.2)
*/
-static int ecjpake_write_zkp( const mbedtls_md_info_t *md_info,
+static int ecjpake_zkp_write( const mbedtls_md_info_t *md_info,
const mbedtls_ecp_group *grp,
const mbedtls_ecp_point *G,
const mbedtls_mpi *x,
@@ -174,6 +174,69 @@
return( ret );
}
+/*
+ * Parse a ECShnorrZKP (7.4.2.2.2) and verify it (7.4.2.3.3)
+ */
+static int ecjpake_zkp_read( const mbedtls_md_info_t *md_info,
+ const mbedtls_ecp_group *grp,
+ const mbedtls_ecp_point *G,
+ const mbedtls_ecp_point *X,
+ const char *id,
+ unsigned char **p,
+ const unsigned char *end )
+{
+ int ret;
+ mbedtls_ecp_point V, VV;
+ mbedtls_mpi r, h;
+ size_t r_len;
+
+ mbedtls_ecp_point_init( &V );
+ mbedtls_ecp_point_init( &VV );
+ mbedtls_mpi_init( &r );
+ mbedtls_mpi_init( &h );
+
+ /*
+ * struct {
+ * ECPoint V;
+ * opaque r<1..2^8-1>;
+ * } ECSchnorrZKP;
+ */
+ if( end < *p )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+ MBEDTLS_MPI_CHK( mbedtls_ecp_tls_read_point( grp, &V,
+ (const unsigned char **) p, end - *p ) );
+
+ if( end < *p || (size_t)( end - *p ) < 1 )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+ r_len = *(*p)++;
+ if( end < *p || (size_t)( end - *p ) < r_len )
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+ MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &r, *p, r_len ) );
+ *p += r_len;
+
+ /*
+ * Verification
+ */
+ MBEDTLS_MPI_CHK( ecjpake_hash( md_info, grp, G, &V, X, id, &h ) );
+ MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( (mbedtls_ecp_group *) grp,
+ &VV, &h, X, &r, G ) );
+
+ if( mbedtls_ecp_point_cmp( &VV, &V ) != 0 )
+ return( MBEDTLS_ERR_ECP_VERIFY_FAILED );
+
+cleanup:
+ mbedtls_ecp_point_free( &V );
+ mbedtls_ecp_point_free( &VV );
+ mbedtls_mpi_free( &r );
+ mbedtls_mpi_free( &h );
+
+ return( ret );
+}
+
+
#if defined(MBEDTLS_SELF_TEST)
#if defined(MBEDTLS_PLATFORM_C)
@@ -293,16 +356,20 @@
mbedtls_printf( "passed\n" );
if( verbose != 0 )
- mbedtls_printf( " ECJPAKE test #2 (zkp, WIP): " );
+ mbedtls_printf( " ECJPAKE test #2 (zkp write/read): " );
MBEDTLS_MPI_CHK( mbedtls_ecp_gen_keypair_base( &grp, &G, &x, &X,
ecjpake_lgc, NULL ) );
p = buf;
- MBEDTLS_MPI_CHK( ecjpake_write_zkp( md_info, &grp, &G, &x, &X, "client",
+ MBEDTLS_MPI_CHK( ecjpake_zkp_write( md_info, &grp, &G, &x, &X, "client",
&p, buf + sizeof( buf ),
ecjpake_lgc, NULL ) );
+ p = buf;
+ MBEDTLS_MPI_CHK( ecjpake_zkp_read( md_info, &grp, &G, &X, "client",
+ &p, buf + sizeof( buf ) ) );
+
if( verbose != 0 )
mbedtls_printf( "passed\n" );
diff --git a/library/ecp.c b/library/ecp.c
index b21e69d..54f51ab 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -403,6 +403,22 @@
}
/*
+ * Compare two points lazyly
+ */
+int mbedtls_ecp_point_cmp( const mbedtls_ecp_point *P,
+ const mbedtls_ecp_point *Q )
+{
+ if( mbedtls_mpi_cmp_mpi( &P->X, &Q->X ) == 0 &&
+ mbedtls_mpi_cmp_mpi( &P->Y, &Q->Y ) == 0 &&
+ mbedtls_mpi_cmp_mpi( &P->Z, &Q->Z ) == 0 )
+ {
+ return( 0 );
+ }
+
+ return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+}
+
+/*
* Import a non-zero point from ASCII strings
*/
int mbedtls_ecp_point_read_string( mbedtls_ecp_point *P, int radix,