Mercurial > dropbear

annotate libtomcrypt/src/pk/dh/dh_shared_secret.c @ 1857:6022df862942

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Use DSCP for IP QoS traffic classes The previous TOS values are deprecated and not used by modern traffic classifiers. This sets AF21 for "interactive" traffic (with a tty). Non-tty traffic sets AF11 - that indicates high throughput but is not lowest priority (which would be CS1 or LE). This differs from the CS1 used by OpenSSH, it lets interactive git over SSH have higher priority than background least effort traffic. Dropbear's settings here should be suitable with the diffservs used by CAKE qdisc.
author Matt Johnston <matt@ucc.asn.au>
date Tue, 25 Jan 2022 17:32:20 +0800
parents 6dba84798cd5
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1471
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 */
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9
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10 #include "tomcrypt.h"
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11
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12 #ifdef LTC_MDH
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13
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14 /**
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15 Create a DH shared secret.
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16 @param private_key The private DH key in the pair
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17 @param public_key The public DH key in the pair
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18 @param out [out] The destination of the shared data
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19 @param outlen [in/out] The max size and resulting size of the shared data.
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20 @return CRYPT_OK if successful
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21 */
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22 int dh_shared_secret(dh_key *private_key, dh_key *public_key,
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23 unsigned char *out, unsigned long *outlen)
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24 {
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25 void *tmp;
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26 unsigned long x;
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27 int err;
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28
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29 LTC_ARGCHK(private_key != NULL);
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30 LTC_ARGCHK(public_key != NULL);
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31 LTC_ARGCHK(out != NULL);
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32 LTC_ARGCHK(outlen != NULL);
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33
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34 /* types valid? */
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35 if (private_key->type != PK_PRIVATE) {
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36 return CRYPT_PK_NOT_PRIVATE;
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37 }
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38
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39 /* same DH group? */
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40 if (mp_cmp(private_key->prime, public_key->prime) != LTC_MP_EQ) { return CRYPT_PK_TYPE_MISMATCH; }
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41 if (mp_cmp(private_key->base, public_key->base) != LTC_MP_EQ) { return CRYPT_PK_TYPE_MISMATCH; }
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42
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43 /* init big numbers */
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44 if ((err = mp_init(&tmp)) != CRYPT_OK) {
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45 return err;
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46 }
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47
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48 /* check public key */
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49 if ((err = dh_check_pubkey(public_key)) != CRYPT_OK) {
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50 goto error;
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51 }
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52
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53 /* compute tmp = y^x mod p */
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54 if ((err = mp_exptmod(public_key->y, private_key->x, private_key->prime, tmp)) != CRYPT_OK) {
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55 goto error;
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56 }
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57
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58 /* enough space for output? */
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59 x = (unsigned long)mp_unsigned_bin_size(tmp);
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60 if (*outlen < x) {
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61 *outlen = x;
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62 err = CRYPT_BUFFER_OVERFLOW;
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63 goto error;
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64 }
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65 if ((err = mp_to_unsigned_bin(tmp, out)) != CRYPT_OK) {
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66 goto error;
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67 }
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68 *outlen = x;
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69 err = CRYPT_OK;
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70
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71 error:
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72 mp_clear(tmp);
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73 return err;
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74 }
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75
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76 #endif /* LTC_MDH */
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77
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78 /* ref: $Format:%D$ */
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79 /* git commit: $Format:%H$ */
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80 /* commit time: $Format:%ai$ */