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annotate libtomcrypt/src/pk/dh/dh_shared_secret.c @ 1902:4a6725ac957c

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Revert "Don't include sk keys at all in KEX list" This reverts git commit f972813ecdc7bb981d25b5a63638bd158f1c8e72. The sk algorithms need to remain in the sigalgs list so that they are included in the server-sig-algs ext-info message sent by the server. RFC8308 for server-sig-algs requires that all algorithms are listed (though OpenSSH client 8.4p1 tested doesn't require that)
author Matt Johnston <matt@ucc.asn.au>
date Thu, 24 Mar 2022 13:42:08 +0800
parents 6dba84798cd5
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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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: $Format:%ai$ */