From 23dcbe3f16e2f0af3d63115af7e0c5b2226748c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?= <mpg2@elzevir.fr>
Date: Thu, 13 Aug 2015 09:37:00 +0200
Subject: [PATCH] Add support for passphrase in the context

---
 include/mbedtls/ecjpake.h |  8 +++++++-
 library/ecjpake.c         | 25 +++++++++++++++++++------
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/include/mbedtls/ecjpake.h b/include/mbedtls/ecjpake.h
index 37aff6c68..1ffdf60f6 100644
--- a/include/mbedtls/ecjpake.h
+++ b/include/mbedtls/ecjpake.h
@@ -42,6 +42,8 @@ typedef struct
 
     mbedtls_mpi xa;                     /**< Our first secret (x1 or x3)    */
     mbedtls_mpi xb;                     /**< Our second secret (x2 or x4)   */
+
+    mbedtls_mpi s;                      /**< Pre-shared secret              */
 } mbedtls_ecjpake_context;
 
 /*
@@ -61,13 +63,17 @@ void mbedtls_ecjpake_init( mbedtls_ecjpake_context *ctx );
  * \param ctx       context to set up
  * \param hash      hash function to use (MBEDTLS_MD_XXX)
  * \param curve     elliptic curve identifier (MBEDTLS_ECP_DP_XXX)
+ * \param secret    shared secret
+ * \param len       length of the shared secret
  *
  * \return          0 if successfull,
  *                  a negative error code otherwise
  */
 int mbedtls_ecjpake_setup( mbedtls_ecjpake_context *ctx,
                            mbedtls_md_type_t hash,
-                           mbedtls_ecp_group_id curve );
+                           mbedtls_ecp_group_id curve,
+                           const unsigned char *secret,
+                           size_t len );
 
 /*
  * \brief           Generate and write contents of ClientHello extension
diff --git a/library/ecjpake.c b/library/ecjpake.c
index 922be205f..47779fc09 100644
--- a/library/ecjpake.c
+++ b/library/ecjpake.c
@@ -54,6 +54,7 @@ void mbedtls_ecjpake_init( mbedtls_ecjpake_context *ctx )
 
     mbedtls_mpi_init( &ctx->xa );
     mbedtls_mpi_init( &ctx->xb );
+    mbedtls_mpi_init( &ctx->s  );
 }
 
 /*
@@ -74,6 +75,7 @@ void mbedtls_ecjpake_free( mbedtls_ecjpake_context *ctx )
 
     mbedtls_mpi_free( &ctx->xa );
     mbedtls_mpi_free( &ctx->xb );
+    mbedtls_mpi_free( &ctx->s  );
 }
 
 /*
@@ -81,17 +83,25 @@ void mbedtls_ecjpake_free( mbedtls_ecjpake_context *ctx )
  */
 int mbedtls_ecjpake_setup( mbedtls_ecjpake_context *ctx,
                            mbedtls_md_type_t hash,
-                           mbedtls_ecp_group_id curve )
+                           mbedtls_ecp_group_id curve,
+                           const unsigned char *secret,
+                           size_t len )
 {
     int ret;
 
     if( ( ctx->md_info = mbedtls_md_info_from_type( hash ) ) == NULL )
         return( MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE );
 
-    if( ( ret = mbedtls_ecp_group_load( &ctx->grp, curve ) ) != 0 )
-        return( ret );
+    MBEDTLS_MPI_CHK( mbedtls_ecp_group_load( &ctx->grp, curve ) );
 
-    return( 0 );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->s, secret, len ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->s, &ctx->s, &ctx->grp.N ) );
+
+cleanup:
+    if( ret != 0 )
+        mbedtls_ecjpake_free( ctx );
+
+    return( ret );
 }
 
 /*
@@ -575,12 +585,15 @@ int mbedtls_ecjpake_self_test( int verbose )
     mbedtls_ecjpake_context ctx;
     unsigned char buf[1000];
     size_t len;
+    char secret[] = "test passphrase";
 
     mbedtls_ecjpake_init( &ctx );
 
     /* Common to all tests */
-    TEST_ASSERT( mbedtls_ecjpake_setup( &ctx, MBEDTLS_MD_SHA256,
-                                        MBEDTLS_ECP_DP_SECP256R1 ) == 0 );
+    TEST_ASSERT( mbedtls_ecjpake_setup( &ctx,
+                    MBEDTLS_MD_SHA256, MBEDTLS_ECP_DP_SECP256R1,
+                    (const unsigned char *) secret,
+                    sizeof( secret ) - 1 ) == 0 );
 
     if( verbose != 0 )
         mbedtls_printf( "  ECJPAKE test #1 (client ext read): " );