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annotate ecdsa.c @ 767:e465ed10c51d ecc

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Be safer with how we handle ltc_ecc_sets[] (particularly with system libtomcrypt) A bit of progress with ecdsa code
author Matt Johnston <matt@ucc.asn.au>
date Tue, 09 Apr 2013 22:44:19 +0800
parents d1575fdc29a6
children 70625eed40c9
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766
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1 #include "includes.h"
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2 #include "dbutil.h"
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3 #include "crypto_desc.h"
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4 #include "ecc.h"
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5
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6 #ifdef DROPBEAR_ECDSA
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7
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8 ecc_key *gen_ecdsa_priv_key(unsigned int bit_size) {
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9 const ltc_ecc_set_type *dp = NULL; // curve domain parameters
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10 // TODO: use raw bytes for the dp rather than the hex strings in libtomcrypt's ecc.c
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11 switch (bit_size) {
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12 #ifdef DROPBEAR_ECC_256
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13 case 256:
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14 dp = ecc_curve_nistp256.dp;
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15 break;
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16 #endif
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17 #ifdef DROPBEAR_ECC_384
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18 case 384:
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19 dp = ecc_curve_nistp384.dp;
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20 break;
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21 #endif
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22 #ifdef DROPBEAR_ECC_521
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23 case 521:
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24 dp = ecc_curve_nistp521.dp;
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25 break;
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26 #endif
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27 }
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28 if (!dp) {
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29 dropbear_exit("Key size %d isn't valid. Try "
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30 #ifdef DROPBEAR_ECC_256
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31 "256 "
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32 #endif
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33 #ifdef DROPBEAR_ECC_384
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34 "384 "
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35 #endif
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36 #ifdef DROPBEAR_ECC_521
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37 "521 "
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38 #endif
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39 , bit_size);
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40 }
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41
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42 ecc_key *new_key = m_malloc(sizeof(*new_key));
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43 if (ecc_make_key_ex(NULL, dropbear_ltc_prng, new_key, dp) != CRYPT_OK) {
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44 dropbear_exit("ECC error");
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45 }
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46 return new_key;
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47 }
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48
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49 ecc_key *buf_get_ecdsa_pub_key(buffer* buf) {
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50 unsigned char *key_ident = NULL, *identifier = NULL;
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51 unsigned int key_ident_len, identifier_len;
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52 buffer *q_buf = NULL;
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53 struct dropbear_ecc_curve **curve;
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54 ecc_key *new_key = NULL;
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55
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56 // string "ecdsa-sha2-[identifier]"
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57 key_ident = buf_getstring(buf, &key_ident_len);
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58 // string "ecdsa-sha2-[identifier]"
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59 identifier = buf_getstring(buf, &identifier_len);
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60
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61 if (key_ident_len != identifier_len + strlen("ecdsa-sha2-")) {
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62 TRACE(("Bad identifier lengths"))
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63 goto out;
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64 }
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65 if (memcmp(&key_ident[strlen("ecdsa-sha2-")], identifier, identifier_len) != 0) {
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66 TRACE(("mismatching identifiers"))
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67 goto out;
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68 }
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69
767
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70 for (curve = dropbear_ecc_curves; *curve; curve++) {
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71 if (memcmp(identifier, (*curve)->name, strlen((*curve)->name)) == 0) {
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72 break;
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73 }
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74 }
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75 if (!*curve) {
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76 TRACE(("couldn't match ecc curve"))
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77 goto out;
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78 }
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79
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80 // string Q
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81 q_buf = buf_getstringbuf(buf);
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82 new_key = buf_get_ecc_raw_pubkey(q_buf, *curve);
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83
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84 out:
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85 if (key_ident) {
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86 m_free(key_ident);
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87 }
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88 if (identifier) {
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89 m_free(identifier);
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90 }
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91 if (q_buf) {
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92 buf_free(q_buf);
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93 q_buf = NULL;
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94 }
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95 TRACE(("leave buf_get_ecdsa_pub_key"))
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96 return new_key;
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97 }
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98
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99
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100 #endif // DROPBEAR_ECDSA