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Viewing changes to libntp/authparity.c

  • Committer: Bazaar Package Importer
  • Author(s): Matt Zimmerman
  • Date: 2004-10-11 16:10:27 UTC
  • mfrom: (1.1.1 upstream)
  • Revision ID: james.westby@ubuntu.com-20041011161027-icyjbji8ujym633o
Tags: 1:4.2.0a-10ubuntu2
Use ntp.ubuntulinux.org instead of pool.ntp.org

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libntp/authparity.c
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/*
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 * auth_parity - set parity on a key/check for odd parity
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 */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#ifdef DES
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#include "ntp_stdlib.h"
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int
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DESauth_parity(
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        u_int32 *key
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        )
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{
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        u_int32 mask;
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        int parity_err;
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        int bitcount;
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        int half;
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        int byte;
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        int i;
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        /*
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         * Go through counting bits in each byte.  Check to see if
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         * each parity bit was set correctly.  If not, note the error
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         * and set it right.
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         */
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        parity_err = 0;
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        for (half = 0; half < 2; half++) {              /* two halves of key */
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                mask = 0x80000000;
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                for (byte = 0; byte < 4; byte++) {      /* 4 bytes per half */
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                        bitcount = 0;
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                        for (i = 0; i < 7; i++) {       /* 7 data bits / byte */
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                                if (key[half] & mask)
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                                    bitcount++;
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                                mask >>= 1;
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                        }
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                        /*
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                         * If bitcount is even, parity must be set.  If
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                         * bitcount is odd, parity must be clear.
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                         */
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                        if ((bitcount & 0x1) == 0) {
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                                if (!(key[half] & mask)) {
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                                        parity_err++;
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                                        key[half] |= mask;
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                                }
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                        } else {
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                                if (key[half] & mask) {
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                                        parity_err++;
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                                        key[half] &= ~mask;
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                                }
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                        }
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                        mask >>= 1;
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                }
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        }
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        /*
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         * Return the result of the parity check.
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         */
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        return (parity_err == 0);
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}
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#else
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int authparity_bs;
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#endif /* DES */