Add special return code for ecdsa length mismatch
diff --git a/include/polarssl/ecp.h b/include/polarssl/ecp.h
index 8886048..93fbe3d 100644
--- a/include/polarssl/ecp.h
+++ b/include/polarssl/ecp.h
@@ -39,6 +39,7 @@
#define POLARSSL_ERR_ECP_MALLOC_FAILED -0x4D80 /**< Memory allocation failed. */
#define POLARSSL_ERR_ECP_RANDOM_FAILED -0x4D00 /**< Generation of random value, such as (ephemeral) key, failed. */
#define POLARSSL_ERR_ECP_INVALID_KEY -0x4C80 /**< Invalid private or public key. */
+#define POLARSSL_ERR_ECP_SIG_LEN_MISMATCH -0x4C00 /**< Signature is valid but shorter than the user-supplied length. */
#ifdef __cplusplus
extern "C" {