From 616d1ca6052307ade19a024127c9c3b0929dfe13 Mon Sep 17 00:00:00 2001
From: Hanno Becker <hanno.becker@arm.com>
Date: Wed, 24 Jan 2018 10:25:05 +0000
Subject: [PATCH] Add support for alternative ECJPAKE implementation

This commit allows users to provide alternative implementations of the
ECJPAKE interface through the configuration option MBEDTLS_ECJPAKE_ALT.
When set, the user must add `ecjpake_alt.h` declaring the same
interface as `ecjpake.h`, as well as add some compilation unit which
implements the functionality. This is in line with the preexisting
support for alternative implementations of other modules.
---
 ChangeLog                  |  2 ++
 include/mbedtls/config.h   |  1 +
 include/mbedtls/ecjpake.h  | 18 +++++++++++++++++-
 library/ecjpake.c          |  3 +++
 library/version_features.c |  3 +++
 5 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index a200d51fb..0b8667bf1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -34,6 +34,8 @@ Features
      The following functions from the ECDH module can be replaced
      with an alternative implementation:
      mbedtls_ecdh_gen_public() and mbedtls_ecdh_compute_shared().
+   * Add support for alternative implementation for ECJPAKE, controlled by
+     new configuration flag MBEDTLS_ECJPAKE_ALT.
 
 API Changes
    * Extend RSA interface by multiple functions allowing structure-
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 5e6b63e82..6f62a8772 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -271,6 +271,7 @@
 //#define MBEDTLS_CMAC_ALT
 //#define MBEDTLS_DES_ALT
 //#define MBEDTLS_DHM_ALT
+//#define MBEDTLS_ECJPAKE_ALT
 //#define MBEDTLS_GCM_ALT
 //#define MBEDTLS_MD2_ALT
 //#define MBEDTLS_MD4_ALT
diff --git a/include/mbedtls/ecjpake.h b/include/mbedtls/ecjpake.h
index 6fcffc777..d86e8207f 100644
--- a/include/mbedtls/ecjpake.h
+++ b/include/mbedtls/ecjpake.h
@@ -44,6 +44,8 @@
 #include "ecp.h"
 #include "md.h"
 
+#if !defined(MBEDTLS_ECJPAKE_ALT)
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -223,17 +225,31 @@ int mbedtls_ecjpake_derive_secret( mbedtls_ecjpake_context *ctx,
  */
 void mbedtls_ecjpake_free( mbedtls_ecjpake_context *ctx );
 
+#ifdef __cplusplus
+}
+#endif
+
+#else  /* MBEDTLS_ECJPAKE_ALT */
+#include "ecjpake_alt.h"
+#endif /* MBEDTLS_ECJPAKE_ALT */
+
 #if defined(MBEDTLS_SELF_TEST)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * \brief          Checkup routine
  *
  * \return         0 if successful, or 1 if a test failed
  */
 int mbedtls_ecjpake_self_test( int verbose );
-#endif
 
 #ifdef __cplusplus
 }
 #endif
 
+#endif /* MBEDTLS_SELF_TEST */
+
 #endif /* ecjpake.h */
diff --git a/library/ecjpake.c b/library/ecjpake.c
index 1fa1c2d80..e8f40862b 100644
--- a/library/ecjpake.c
+++ b/library/ecjpake.c
@@ -36,6 +36,8 @@
 
 #include <string.h>
 
+#if !defined(MBEDTLS_ECJPAKE_ALT)
+
 /*
  * Convert a mbedtls_ecjpake_role to identifier string
  */
@@ -764,6 +766,7 @@ cleanup:
 #undef ID_MINE
 #undef ID_PEER
 
+#endif /* ! MBEDTLS_ECJPAKE_ALT */
 
 #if defined(MBEDTLS_SELF_TEST)
 
diff --git a/library/version_features.c b/library/version_features.c
index ede2276a5..72afec2da 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -108,6 +108,9 @@ static const char *features[] = {
 #if defined(MBEDTLS_DHM_ALT)
     "MBEDTLS_DHM_ALT",
 #endif /* MBEDTLS_DHM_ALT */
+#if defined(MBEDTLS_ECJPAKE_ALT)
+    "MBEDTLS_ECJPAKE_ALT",
+#endif /* MBEDTLS_ECJPAKE_ALT */
 #if defined(MBEDTLS_GCM_ALT)
     "MBEDTLS_GCM_ALT",
 #endif /* MBEDTLS_GCM_ALT */