On Wed, Apr 05, 2023 at 12:34:09PM +0000, Viken Kondakji wrote: > Re my question about endianness, I am not in control. > I am required to do what the target destination tells me to do. It is that simple. > > So, I ask again: > Will the binary output of the EVP_PKEY_encrypt on a small-endian host produce binary data in big-endian? > Can anyone help, please. The output is a bytestring not an integer, so the endianness question is not applicable. That said, the serialisation of primitive RSA encryption operation results is "big-endian" per various specifications. You still should not use (or at least treat with great scepticisim) any protocol where you're performing raw RSA encryption operations. -- Viktor.