Add tests and fix bugs for RSA-alt contexts
diff --git a/include/polarssl/pk.h b/include/polarssl/pk.h
index 6f21dab..b764d55 100644
--- a/include/polarssl/pk.h
+++ b/include/polarssl/pk.h
@@ -234,7 +234,7 @@
* \param key RSA key pointer
* \param decrypt_func Decryption function
* \param sign_func Signing function
- * \param key_len_func Function returning key length
+ * \param key_len_func Function returning key length in bytes
*
* \return 0 on success, or POLARSSL_ERR_PK_BAD_INPUT_DATA if the
* context wasn't already initialized as RSA_ALT.