mbedtls_ct_rsaes_pkcs1_v15_unpadding() function

\c 0 on success. #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE The output buffer is too small for the unpadded payload. #MBEDTLS_ERR_RSA_INVALID_PADDING The input doesn't contain properly formatted padding.

The return value from this function is a sensitive value (this is unusual). #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE shouldn't happen in a well-written application, but 0 vs #MBEDTLS_ERR_RSA_INVALID_PADDING is often a situation that an attacker can provoke and leaking which one is the result is precisely the information the attacker wants.