pgptrstpkt.h

著名的加密软件的应用于电子邮件中

/*
* pgpTrstPkt.h
*
* Copyright (C) 1994-1997 Pretty Good Privacy, Inc. All rights reserved.
*
* $Id: pgpTrstPkt.h,v 1.4.2.1 1997/06/07 09:50:44 mhw Exp $
*/

#ifndef PGPTRSTPKT_H
#define PGPTRSTPKT_H

/*
* Key trust byte:
* 8 +--+
*   |  | BUCKSTOP bit - this is an axiomatic key
* 7 +--+
*   |  |
* 6 +--+
*   |  | Disabled - don't use at user request
* 5 +--+
*   |  | Revoked - don't use at issuer request
* 4 +--+
*   |  |
* 3 +--+
*   |  | Introducer trust. 6 levels are used:
* 2 +  + 000 - undefined, need to ask user
*   |  | 001 - Unknown, consider to be zero
* 1 +  + 010 - Not trusted
*   |  | 011 - unused
* 0 +--+ 100 - unused
*        101 - Marginal - partially trusted
*        110 - Complete - completely trusted
*        111 - Ultimate - ultimately trusted
*/

#define PGP_KEYTRUSTF_BUCKSTOP	0x80u
#define PGP_KEYTRUSTF_EXPIRED 0x40u
#define PGP_KEYTRUSTF_DISABLED	0x20u
#define PGP_KEYTRUSTF_REVOKED	0x10u

#define PGP_KEYTRUST_MASK 0x7u
#define PGP_KEYTRUST_UNDEFINED	0x0u
#define PGP_KEYTRUST_UNKNOWN	0x1u
#define PGP_KEYTRUST_NEVER	0x2u
#define PGP_KEYTRUST_MARGINAL	0x5u
#define PGP_KEYTRUST_COMPLETE	0x6u
#define PGP_KEYTRUST_ULTIMATE	0x7u

/*
 * Name trust byte:
 * 8 +--+
 *   |  | WARNONLY bit - yes, it's okay to use even though not fully trusted
 * 7 +--+
 *   |  | unused
 * 6 +--+
 *   |  | unused
 * 5 +--+
 *   |  | unused
 * 4 +--+
 *   |  | unused
 * 3 +--+
 *   |  | unused
 * 2 +--+
 *   |  | Confidence in name's validity.
 * 1 +  + 00 - Not known
 *   |  | 01 - Not trusted
 * 0 +--+ 10 - Partially trusted
 *        11 - Completely trusted
 *
 * New trust packets are followed by up to two more bytes, which are the
 * certainty PGP has of the name's validity and the confidence the user
 * has assigned to this name as an introducer, respectively. The byte
 * b represents probability of 10^(-b/40) that the name is incorrect,
 * up to 252. 255 means "total confidence", 253 means confidence is
 * undefined, and 254 is reserved for now.
 *
 * @@@ Reserve 0 for "undefined/I dunno", 1 for "untrusted" and offset
 * everything that way. It might be more natural...
 *
 * The following pattern repeats each 40:
 *
 *	0 = 1.00000	9 = 1.67880	18 = 2.81838	27 = 4.73151	36 = 7.94328
 *	1 = 1.05925	10 = 1.77828	19 = 2.98538	28 = 5.01187	37 = 8.41395
 *	2 = 1.12202	11 = 1.88365	20 = 3.16228	29 = 5.30884	38 = 8.91251
 *	3 = 1.18850	12 = 1.99526	21 = 3.34965	30 = 5.62341	39 = 9.44061
 *	4 = 1.25893	13 = 2.11349	22 = 3.54813	31 = 5.95662	40 = 10.0000
 *	5 = 1.33352	14 = 2.23872	23 = 3.75837	32 = 6.30957	41 = 10.5925
 *	6 = 1.41254	15 = 2.37137	24 = 3.98107	33 = 6.68344	42 = 11.2202
 *	7 = 1.49624	16 = 2.51189	25 = 4.21697	34 = 7.07946	43 = 11.8850
 *	8 = 1.58489	17 = 2.66073	26 = 4.46684	35 = 7.49894	44 = 12.5893
 *
 * As you can see, f(12) ~= 2, f(19) ~= 3, * and f(24) ~= 4.
 * The converse of this is that f(40-12) = f(28) = 10/f(12) ~= 10/2 = 5
 * and similarly f(21) ~= 10/3 = 3.33 and f(16) ~= 10/4 = 2.5.
 * The system was chosen because all of those nice integer ratios
 * work out.
 *
 * This is very close to 2^(-b/12), the difference being the 1024/1000
 * mismatch that programmers are used to ignoring. Thus, each 12 steps
 * is an octave and each single step is a semitone.
 *
 * From the API, these values are translated to 16-bit values, which are
 * all the programmer sees. The 16-bit values are shifted by 6 bits,
 * giving a minimum representable error of abut 2.5*10^-26.
 */
#define PGP_NAMETRUSTF_WARNONLY	0x80u

#define PGP_NAMETRUST_MASK 0x3u
#define PGP_NAMETRUST_UNKNOWN	0x0u
#define PGP_NAMETRUST_UNTRUSTED	0x1u
#define PGP_NAMETRUST_MARGINAL	0x2u
#define PGP_NAMETRUST_COMPLETE	0x3u

/* The following bytes apply to validity and confidence bytes on names */
#define PGP_NEWTRUST_MAX 252
#define PGP_NEWTRUST_UNDEFINED 253
#define PGP_NEWTRUST_INFINITE	255

/*
 * Signature trust byte:
 * 8 +--+
 *   |  | unused
 * 7 +--+
 *   |  | Checked - Signature is good
 * 6 +--+
 *   |  | Tried - Signature verification attempted
 * 5 +--+
 *   |  | unused
 * 4 +--+
 *   |  | unused
 * 3 +--+
 *   |  | Introducer trust, copied from key that makes it
 * 2 +  +
 *   |  |
 * 1 +  +
 *   |  |
 * 0 +--+
 */

/*
* The low 3 bits of a signature's trust are generally the same as
* the corresponding key's trust (PGP_KEYTRUST_UNDEFINED if none), but
* the following signature pseudo-trusts used in some printing contexts:
*/
#define PGP_SIGTRUST_NOKEY	0x8u	/* No corresponding key */
#define PGP_SIGTRUST_RETIRED 0x9u /* Retired/sig revoked */
#define PGP_SIGTRUST_REVOKED 0xAu /* Signing key revoked */
#define PGP_SIGTRUST_UNTRIED	0xBu	/* Signature has not been tried */
#define PGP_SIGTRUST_INVALID	0xCu	/* Invalid signature or something */
#define PGP_SIGTRUST_BAD	0xDu	/* BAD SIGNATURE */

/*
* There are four possible signature states worth noting, actually:
* - No verification attempted (includes key not found)
* - Verification impossible (format problem or key length)
* - Verified bad (format correct, but signature is no good)
* - Verified good
*
* In practice, the middle two can be merged, and the last marked by
* the PGP_SIGTRUSTF_CHECKED bit for compatibility with 2.x. The first two
* can be distinguidhed through the use of the PGP_SIGTRUSTF_TRIED bit.
* If clear, the signature's verification has never been attempted.
*
* At some future point, we should make CHECKED=1 and TRIED=0 mean that
* a signature was bad, but postpone on that for a while; the state is
* CHECKED=0, TRIED=1 for now. If we see CHECKED set, that implies
* TRIED.
*/
#define PGP_SIGTRUSTF_TRIED	 0x20u	/* Visited by sig check (-kc) */
#define PGP_SIGTRUSTF_CHECKED	0x40u	/* Checked out good */
#define PGP_SIGTRUSTF_CHECKED_TRIED (PGP_SIGTRUSTF_CHECKED | \
						PGP_SIGTRUSTF_TRIED)

#ifdef __cplusplus
extern "C" {
#endif

extern char const PGPExport *keyTrustTable[];
extern char const PGPExport *uidValidityTable[];

#ifdef __cplusplus
}
#endif

#endif /* PGPTRSTPKT_H */