Implement sig_hashes
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 22b07bc..391ce5b 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -374,11 +374,17 @@
 #endif
 
 mbedtls_md_type_t mbedtls_ssl_md_alg_from_hash( unsigned char hash );
+unsigned char mbedtls_ssl_hash_from_md_alg( int md );
 
 #if defined(MBEDTLS_ECP_C)
 int mbedtls_ssl_check_curve( const mbedtls_ssl_context *ssl, mbedtls_ecp_group_id grp_id );
 #endif
 
+#if defined(MBEDTLS_KEY_EXCHANGE__SOME__SIGNATURE_ENABLED)
+int mbedtls_ssl_check_sig_hash( const mbedtls_ssl_context *ssl,
+                                mbedtls_md_type_t md );
+#endif
+
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
 static inline mbedtls_pk_context *mbedtls_ssl_own_key( mbedtls_ssl_context *ssl )
 {