jc> contains a SHA-1 hash of plaintext data jc> The plaintext of the data to be encrypted An ambiguity quibble. This is meant to refer to the octets of the compressed/encoded packet as seen by the CFB envelope, as opposed to the uncompressed/decoded data as seen by the end users? I see the hint buried in 5.14, but pleeease make it more explicit in 5.13...