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annotate libtomcrypt/src/pk/dh/dh_generate_key.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:
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 static int _dh_groupsize_to_keysize(int groupsize)
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15 {
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16 /* The strength estimates from https://tools.ietf.org/html/rfc3526#section-8
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17 * We use "Estimate 2" to get an appropriate private key (exponent) size.
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18 */
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19 if (groupsize <= 0) {
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20 return 0;
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21 }
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22 else if (groupsize <= 192) {
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23 return 30; /* 1536-bit => key size 240-bit */
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24 }
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25 else if (groupsize <= 256) {
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26 return 40; /* 2048-bit => key size 320-bit */
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27 }
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28 else if (groupsize <= 384) {
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29 return 52; /* 3072-bit => key size 416-bit */
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30 }
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31 else if (groupsize <= 512) {
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32 return 60; /* 4096-bit => key size 480-bit */
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33 }
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34 else if (groupsize <= 768) {
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35 return 67; /* 6144-bit => key size 536-bit */
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36 }
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37 else if (groupsize <= 1024) {
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38 return 77; /* 8192-bit => key size 616-bit */
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39 }
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40 else {
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41 return 0;
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42 }
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43 }
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44
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45 int dh_generate_key(prng_state *prng, int wprng, dh_key *key)
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46 {
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47 unsigned char *buf;
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48 unsigned long keysize;
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49 int err, max_iterations = LTC_PK_MAX_RETRIES;
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50
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51 LTC_ARGCHK(key != NULL);
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52 LTC_ARGCHK(ltc_mp.name != NULL);
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53
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54 /* good prng? */
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55 if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
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56 return err;
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57 }
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58
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59 keysize = _dh_groupsize_to_keysize(mp_unsigned_bin_size(key->prime));
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60 if (keysize == 0) {
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61 err = CRYPT_INVALID_KEYSIZE;
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62 goto freemp;
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63 }
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64
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65 /* allocate buffer */
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66 buf = XMALLOC(keysize);
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67 if (buf == NULL) {
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68 err = CRYPT_MEM;
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69 goto freemp;
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70 }
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71
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72 key->type = PK_PRIVATE;
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73 do {
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74 /* make up random buf */
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75 if (prng_descriptor[wprng].read(buf, keysize, prng) != keysize) {
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76 err = CRYPT_ERROR_READPRNG;
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77 goto freebuf;
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78 }
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79 /* load the x value - private key */
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80 if ((err = mp_read_unsigned_bin(key->x, buf, keysize)) != CRYPT_OK) {
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81 goto freebuf;
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82 }
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83 /* compute the y value - public key */
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84 if ((err = mp_exptmod(key->base, key->x, key->prime, key->y)) != CRYPT_OK) {
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85 goto freebuf;
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86 }
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87 err = dh_check_pubkey(key);
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88 } while (err != CRYPT_OK && max_iterations-- > 0);
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89
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90 freebuf:
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91 zeromem(buf, keysize);
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92 XFREE(buf);
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93 freemp:
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94 if (err != CRYPT_OK) dh_free(key);
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95 return err;
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96 }
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97
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98 #endif /* LTC_MDH */
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99
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100 /* ref: $Format:%D$ */
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101 /* git commit: $Format:%H$ */
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102 /* commit time: $Format:%ai$ */