On 18/04/16 15:55, Dmitry Belyavsky wrote: > Hello, > > Could anybody explain how to deal with the output length in the > EVP_EncryptUpdate? > > The function EVP_EncryptUpdate has the outl output parameter, which is > designed for returning the length of the resulting ciphertext. Then > internally it calls the do_cipher callback which does not take such a > parameter. > > Is there a way to return an expected buffer length from the callback? > It may be necessary when we call the EVP_EncryptUpdate some times, and > we get the case when ctx->buf from the previous calls has enough bytes > to be processed together with the input buffer so the output is longer > then the input. The man page advises that the size of the output buffer should be: inl + cipher_block_size - 1 This should cater for all eventualities. Matt
