[openssl-users] EVP_EncryptUpdate and EVP_CIPHER callback do_cipher

[Dmitry Belyavsky]

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.

Thank you!

-- 
SY, Dmitry Belyavsky
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