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Revision 1.1, Thu Nov 21 00:45:44 2013 UTC (10 years, 6 months ago) by djm
Branch: MAIN
CVS Tags: OPENBSD_5_5_BASE, OPENBSD_5_5 

Add a new protocol 2 transport cipher "chacha20-poly1305@openssh.com"
that combines Daniel Bernstein's ChaCha20 stream cipher and Poly1305 MAC
to build an authenticated encryption mode.

Inspired by and similar to Adam Langley's proposal for TLS:
http://tools.ietf.org/html/draft-agl-tls-chacha20poly1305-03
but differs in layout used for the MAC calculation and the use of a
second ChaCha20 instance to separately encrypt packet lengths.
Details are in the PROTOCOL.chacha20poly1305 file.

Feedback markus@, naddy@; manpage bits Loganden Velvindron @ AfriNIC
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/* $OpenBSD: chacha.h,v 1.1 2013/11/21 00:45:44 djm Exp $ */

/*
chacha-merged.c version 20080118
D. J. Bernstein
Public domain.
*/

#ifndef CHACHA_H
#define CHACHA_H

#include <sys/types.h>

struct chacha_ctx {
	u_int input[16];
};

#define CHACHA_MINKEYLEN 	16
#define CHACHA_NONCELEN		8
#define CHACHA_CTRLEN		8
#define CHACHA_STATELEN		(CHACHA_NONCELEN+CHACHA_CTRLEN)
#define CHACHA_BLOCKLEN		64

void chacha_keysetup(struct chacha_ctx *x, const u_char *k, u_int kbits)
    __attribute__((__bounded__(__minbytes__, 2, CHACHA_MINKEYLEN)));
void chacha_ivsetup(struct chacha_ctx *x, const u_char *iv, const u_char *ctr)
    __attribute__((__bounded__(__minbytes__, 2, CHACHA_NONCELEN)))
    __attribute__((__bounded__(__minbytes__, 3, CHACHA_CTRLEN)));
void chacha_encrypt_bytes(struct chacha_ctx *x, const u_char *m,
    u_char *c, u_int bytes)
    __attribute__((__bounded__(__buffer__, 2, 4)))
    __attribute__((__bounded__(__buffer__, 3, 4)));

#endif	/* CHACHA_H */