annotate libtomcrypt/src/pk/dsa/dsa_decrypt_key.c @ 745:15999b098cc9 kexguess

Don't usually need to recalculate dh_e for the repeated kexdh_init packet
author Matt Johnston <matt@ucc.asn.au>
date Wed, 03 Apr 2013 00:32:55 +0800
parents 0cbe8f6dbf9e
children f849a5ca2efc
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
382
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diff changeset
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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diff changeset
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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diff changeset
7 * guarantee it works.
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8 *
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9 * Tom St Denis, [email protected], http://libtomcrypt.com
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diff changeset
10 */
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diff changeset
11 #include "tomcrypt.h"
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12
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13 /**
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14 @file dsa_decrypt_key.c
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15 DSA Crypto, Tom St Denis
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16 */
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17
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18 #ifdef MDSA
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19
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20 /**
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21 Decrypt an DSA encrypted key
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22 @param in The ciphertext
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23 @param inlen The length of the ciphertext (octets)
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24 @param out [out] The plaintext
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25 @param outlen [in/out] The max size and resulting size of the plaintext
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26 @param key The corresponding private DSA key
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27 @return CRYPT_OK if successful
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28 */
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29 int dsa_decrypt_key(const unsigned char *in, unsigned long inlen,
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30 unsigned char *out, unsigned long *outlen,
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31 dsa_key *key)
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32 {
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33 unsigned char *skey, *expt;
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34 void *g_pub;
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35 unsigned long x, y, hashOID[32];
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36 int hash, err;
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37 ltc_asn1_list decode[3];
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38
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39 LTC_ARGCHK(in != NULL);
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40 LTC_ARGCHK(out != NULL);
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41 LTC_ARGCHK(outlen != NULL);
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42 LTC_ARGCHK(key != NULL);
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43
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44 /* right key type? */
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45 if (key->type != PK_PRIVATE) {
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46 return CRYPT_PK_NOT_PRIVATE;
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47 }
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48
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49 /* decode to find out hash */
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50 LTC_SET_ASN1(decode, 0, LTC_ASN1_OBJECT_IDENTIFIER, hashOID, sizeof(hashOID)/sizeof(hashOID[0]));
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51
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52 if ((err = der_decode_sequence(in, inlen, decode, 1)) != CRYPT_OK) {
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53 return err;
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54 }
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55
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56 hash = find_hash_oid(hashOID, decode[0].size);
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57 if (hash_is_valid(hash) != CRYPT_OK) {
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58 return CRYPT_INVALID_PACKET;
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59 }
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60
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61 /* we now have the hash! */
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62
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63 if ((err = mp_init(&g_pub)) != CRYPT_OK) {
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64 return err;
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65 }
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66
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67 /* allocate memory */
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68 expt = XMALLOC(mp_unsigned_bin_size(key->p) + 1);
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69 skey = XMALLOC(MAXBLOCKSIZE);
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70 if (expt == NULL || skey == NULL) {
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Matt Johnston <matt@ucc.asn.au>
parents:
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71 if (expt != NULL) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
72 XFREE(expt);
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73 }
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
74 if (skey != NULL) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
75 XFREE(skey);
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76 }
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
77 mp_clear(g_pub);
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
78 return CRYPT_MEM;
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
79 }
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
80
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
81 LTC_SET_ASN1(decode, 1, LTC_ASN1_INTEGER, g_pub, 1UL);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
82 LTC_SET_ASN1(decode, 2, LTC_ASN1_OCTET_STRING, skey, MAXBLOCKSIZE);
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
83
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
84 /* read the structure in now */
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
85 if ((err = der_decode_sequence(in, inlen, decode, 3)) != CRYPT_OK) {
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
86 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
87 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
88
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
89 /* make shared key */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
90 x = mp_unsigned_bin_size(key->p) + 1;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
91 if ((err = dsa_shared_secret(key->x, g_pub, key, expt, &x)) != CRYPT_OK) {
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
92 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
93 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
94
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
95 y = MIN(mp_unsigned_bin_size(key->p) + 1, MAXBLOCKSIZE);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
96 if ((err = hash_memory(hash, expt, x, expt, &y)) != CRYPT_OK) {
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
97 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
98 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
99
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
100 /* ensure the hash of the shared secret is at least as big as the encrypt itself */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
101 if (decode[2].size > y) {
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
102 err = CRYPT_INVALID_PACKET;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
103 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
104 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
105
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
106 /* avoid buffer overflow */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
107 if (*outlen < decode[2].size) {
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
108 *outlen = decode[2].size;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
109 err = CRYPT_BUFFER_OVERFLOW;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
110 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
111 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
112
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
113 /* Decrypt the key */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
114 for (x = 0; x < decode[2].size; x++) {
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
115 out[x] = expt[x] ^ skey[x];
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
116 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
117 *outlen = x;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
118
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
119 err = CRYPT_OK;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
120 LBL_ERR:
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
121 #ifdef LTC_CLEAN_STACK
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
122 zeromem(expt, mp_unsigned_bin_size(key->p) + 1);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
123 zeromem(skey, MAXBLOCKSIZE);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
124 #endif
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
125
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
126 XFREE(expt);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
127 XFREE(skey);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
128
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
129 mp_clear(g_pub);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
130
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
131 return err;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
132 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
133
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
134 #endif
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
135
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
136 /* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_decrypt_key.c,v $ */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
137 /* $Revision: 1.9 $ */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
138 /* $Date: 2006/12/04 03:18:43 $ */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
139