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/* frames/frame.h
*
* Framing information for eKey protocol
*
* Copyright 2009 Simtec Electronics
*
* For licence terms refer to the COPYING file.
*/
#ifndef EKEY_FRAMES_FRAME_H
#define EKEY_FRAMES_FRAME_H
/*
* The following holds true for all frames
* Frames start with a SOF of '* '
* Frames end with an EOF of '\r\n'
* Frames have a frame type indicator which is two characters.
* Frames have a PEM64 encoded 48 bit MAC (eight characters).
* Frame payloads are always 48 bytes long.
* Frames are always 64 bytes from start of SOF to end of EOF.
* Thus, we have 2 + 2 + N + 8 + 2 => 64, so the payload
* is always 50 characters.
*
*/
/**
* Prepare the framer's MAC skein
*
* @param sharedkey The shared secret (32 bytes)
*/
extern void framer_prepare_mac(const unsigned char *sharedkey);
/**
* Compute a MAC for a frame.
*
* @param frame The frame to compute the MAC for. Note, The SOF and
* EOF are not considered to be part of the frame.
* @param mactarget The location to write the computed pem64'd MAC to.
* @note frame must point at the frame type (i.e. not the SOF) as the
* MAC is computed on the frame type and payload only.
*/
extern void framer_compute_mac(const char *frame, char *mactarget);
/**
* Frame a payload into a frame packet.
*
* @param frame The frame to fill out.
* @param ft1 The first character of the frame type,
* @param ft2 The second character of the frame type,
* @param payload The payload (must be 50 bytes).
*
* @note If payload is < 50 bytes but NULL terminated, then it will be
* padded with ' '.
* @note The caller is expected to fill out the SOF and EOF which will
* not be read nor written by this routine, but which are expected
* to be present by other routines.
* @note \a frame should point at the SOF (or location there-for), this
* routine will then fill out from frame[2] with \a ft1...
*/
extern void framer_fill_frame(char *frame, char ft1, char ft2, char *payload);
#endif /* EKEY_FRAMES_FRAME_H */
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