commit ecaba1c9b24cbab31f98bc8fecef30c88b1398dc
author Neil Armstrong <narmstrong@baylibre.com> Thu Aug 11 10:47:08 2022 +0200
committer Neil Armstrong <narmstrong@baylibre.com> Fri Aug 19 11:49:22 2022 +0200
tree add7a3a3f007aa2beccf0b9474b1d59f6337bc7c
parent 0d76341eace52010cbf1d8f6e2b5054455614eb9

Make use of PSA crypto hash if MBEDTLS_MD_C isn't defined

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

include/mbedtls/check_config.h

diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 719ffb7..b83fce5 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -108,7 +108,8 @@
 #endif
 
 #if defined(MBEDTLS_ECJPAKE_C) &&           \
-    ( !defined(MBEDTLS_ECP_C) || !defined(MBEDTLS_MD_C) )
+    ( !defined(MBEDTLS_ECP_C) ||            \
+      !( defined(MBEDTLS_MD_C) || defined(MBEDTLS_PSA_CRYPTO_C) ) )
 #error "MBEDTLS_ECJPAKE_C defined, but not all prerequisites"
 #endif
 

include/mbedtls/mbedtls_config.h

diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index d7662ef..044403f 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -2330,6 +2330,9 @@
  *      ECJPAKE
  *
  * Requires: MBEDTLS_ECP_C, MBEDTLS_MD_C
+ *
+ * \warning If building without MBEDTLS_MD_C, you must call psa_crypto_init()
+ * before doing any EC J-PAKE operations.
  */
 #define MBEDTLS_ECJPAKE_C
 

library/ecjpake.c

diff --git a/library/ecjpake.c b/library/ecjpake.c
index 10286c2..7447354 100644
--- a/library/ecjpake.c
+++ b/library/ecjpake.c
@@ -30,6 +30,13 @@
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
 
+/* We use MD first if it's available (for compatibility reasons)
+ * and "fall back" to PSA otherwise (which needs psa_crypto_init()). */
+#if !defined(MBEDTLS_MD_C)
+#include "psa/crypto.h"
+#include "mbedtls/psa_util.h"
+#endif /* !MBEDTLS_MD_C */
+
 #include "hash_info.h"
 
 #include <string.h>
@@ -47,6 +54,28 @@
 #define ID_MINE     ( ecjpake_id[ ctx->role ] )
 #define ID_PEER     ( ecjpake_id[ 1 - ctx->role ] )
 
+/**
+  * Helper to Compute a hash from md_type
+  */
+static int mbedtls_ecjpake_compute_hash( mbedtls_md_type_t md_type,
+                                    const unsigned char *input, size_t ilen,
+                                    unsigned char *output )
+{
+#if defined(MBEDTLS_MD_C)
+    return( mbedtls_md( mbedtls_md_info_from_type( md_type ),
+                        input, ilen, output ) );
+#else
+    psa_algorithm_t alg = mbedtls_psa_translate_md( md_type );
+    psa_status_t status;
+    size_t out_size = PSA_HASH_LENGTH( alg );
+    size_t out_len;
+
+    status = psa_hash_compute( alg, input, ilen, output, out_size, &out_len );
+
+    return( mbedtls_md_error_from_psa( status ) );
+#endif /* !MBEDTLS_MD_C */
+}
+
 /*
  * Initialize context
  */
@@ -106,8 +135,13 @@
 
     ctx->role = role;
 
+#if defined(MBEDTLS_MD_C)
     if( ( mbedtls_md_info_from_type( hash ) ) == NULL )
         return( MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE );
+#else
+    if( mbedtls_psa_translate_md( hash ) == MBEDTLS_MD_NONE )
+        return( MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE );
+#endif
 
     ctx->md_type = hash;
 
@@ -222,8 +256,8 @@
     p += id_len;
 
     /* Compute hash */
-    MBEDTLS_MPI_CHK( mbedtls_md( mbedtls_md_info_from_type( md_type ),
-                                 buf, p - buf, hash ) );
+    MBEDTLS_MPI_CHK( mbedtls_ecjpake_compute_hash( md_type,
+                                                   buf, p - buf, hash ) );
 
     /* Turn it into an integer mod n */
     MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( h, hash,
@@ -763,8 +797,8 @@
     /* PMS = SHA-256( K.X ) */
     x_bytes = ( ctx->grp.pbits + 7 ) / 8;
     MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &K.X, kx, x_bytes ) );
-    MBEDTLS_MPI_CHK( mbedtls_md( mbedtls_md_info_from_type( ctx->md_type ),
-                                 kx, x_bytes, buf ) );
+    MBEDTLS_MPI_CHK( mbedtls_ecjpake_compute_hash( ctx->md_type,
+                                                   kx, x_bytes, buf ) );
 
 cleanup:
     mbedtls_ecp_point_free( &K );