Merge remote-tracking branch 'upstream-public/pr/1027' into development
diff --git a/ChangeLog b/ChangeLog
index 2284f34..54a740a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -22,6 +22,12 @@
      MBEDTLS_CMAC_ALT). Submitted by Steve Cooreman, Silicon Labs.
    * Add support for alternative implementations of GCM, selected by the
      configuration flag MBEDTLS_GCM_ALT.
+   * Add support for alternative implementations for ECDSA, controlled by new
+     configuration flags MBEDTLS_ECDSA_SIGN_ALT, MBEDTLS_ECDSA_VERIFY_ALT and
+     MBEDTLS_ECDSDA_GENKEY_AT in config.h.
+     The following functions from the ECDSA module can be replaced
+     with alternative implementation:
+     mbedtls_ecdsa_sign(), mbedtls_ecdsa_verify() and mbedtls_ecdsa_genkey().
 
 New deprecations
    * Deprecate usage of RSA primitives with non-matching key-type
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 7c06815..1848ac1 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -332,6 +332,9 @@
 //#define MBEDTLS_AES_SETKEY_DEC_ALT
 //#define MBEDTLS_AES_ENCRYPT_ALT
 //#define MBEDTLS_AES_DECRYPT_ALT
+//#define MBEDTLS_ECDSA_VERIFY_ALT
+//#define MBEDTLS_ECDSA_SIGN_ALT
+//#define MBEDTLS_ECDSA_GENKEY_ALT
 
 /**
  * \def MBEDTLS_ECP_INTERNAL_ALT
diff --git a/library/ecdsa.c b/library/ecdsa.c
index 8892317..826fefe 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -65,6 +65,7 @@
     return( ret );
 }
 
+#if !defined(MBEDTLS_ECDSA_SIGN_ALT)
 /*
  * Compute ECDSA signature of a hashed message (SEC1 4.1.3)
  * Obviously, compared to SEC1 4.1.3, we skip step 4 (hash message)
@@ -157,6 +158,7 @@
 
     return( ret );
 }
+#endif /* MBEDTLS_ECDSA_SIGN_ALT */
 
 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
 /*
@@ -196,6 +198,7 @@
 }
 #endif /* MBEDTLS_ECDSA_DETERMINISTIC */
 
+#if !defined(MBEDTLS_ECDSA_VERIFY_ALT)
 /*
  * Verify ECDSA signature of hashed message (SEC1 4.1.4)
  * Obviously, compared to SEC1 4.1.3, we skip step 2 (hash message)
@@ -281,6 +284,7 @@
 
     return( ret );
 }
+#endif /* MBEDTLS_ECDSA_VERIFY_ALT */
 
 /*
  * Convert a signature (given by context) to ASN.1
@@ -406,6 +410,7 @@
     return( ret );
 }
 
+#if !defined(MBEDTLS_ECDSA_GENKEY_ALT)
 /*
  * Generate key pair
  */
@@ -415,6 +420,7 @@
     return( mbedtls_ecp_group_load( &ctx->grp, gid ) ||
             mbedtls_ecp_gen_keypair( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) );
 }
+#endif /* MBEDTLS_ECDSA_GENKEY_ALT */
 
 /*
  * Set context from an mbedtls_ecp_keypair
diff --git a/library/version_features.c b/library/version_features.c
index 49bba11..ceebcb0 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -177,6 +177,15 @@
 #if defined(MBEDTLS_AES_DECRYPT_ALT)
     "MBEDTLS_AES_DECRYPT_ALT",
 #endif /* MBEDTLS_AES_DECRYPT_ALT */
+#if defined(MBEDTLS_ECDSA_VERIFY_ALT)
+    "MBEDTLS_ECDSA_VERIFY_ALT",
+#endif /* MBEDTLS_ECDSA_VERIFY_ALT */
+#if defined(MBEDTLS_ECDSA_SIGN_ALT)
+    "MBEDTLS_ECDSA_SIGN_ALT",
+#endif /* MBEDTLS_ECDSA_SIGN_ALT */
+#if defined(MBEDTLS_ECDSA_GENKEY_ALT)
+    "MBEDTLS_ECDSA_GENKEY_ALT",
+#endif /* MBEDTLS_ECDSA_GENKEY_ALT */
 #if defined(MBEDTLS_ECP_INTERNAL_ALT)
     "MBEDTLS_ECP_INTERNAL_ALT",
 #endif /* MBEDTLS_ECP_INTERNAL_ALT */