Mercurial > dropbear

annotate libtomcrypt/src/pk/ecc/ecc_decrypt_key.c @ 473:170329dc8ce5 DROPBEAR_0.51

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Forgot to bump actual version number
author Matt Johnston <matt@ucc.asn.au>
date Thu, 27 Mar 2008 13:34:34 +0000
parents 0cbe8f6dbf9e
children ac2158e3e403
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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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 * Tom St Denis, [email protected], http://libtomcrypt.com
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10 */
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11
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12 /* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
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13 *
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14 * All curves taken from NIST recommendation paper of July 1999
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15 * Available at http://csrc.nist.gov/cryptval/dss.htm
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16 */
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17 #include "tomcrypt.h"
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18
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19 /**
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20 @file ecc_decrypt_key.c
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21 ECC Crypto, Tom St Denis
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22 */
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23
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24 #ifdef MECC
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25
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26 /**
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27 Decrypt an ECC encrypted key
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28 @param in The ciphertext
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29 @param inlen The length of the ciphertext (octets)
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30 @param out [out] The plaintext
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31 @param outlen [in/out] The max size and resulting size of the plaintext
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32 @param key The corresponding private ECC key
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33 @return CRYPT_OK if successful
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34 */
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35 int ecc_decrypt_key(const unsigned char *in, unsigned long inlen,
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36 unsigned char *out, unsigned long *outlen,
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37 ecc_key *key)
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38 {
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39 unsigned char *ecc_shared, *skey, *pub_expt;
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40 unsigned long x, y, hashOID[32];
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41 int hash, err;
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42 ecc_key pubkey;
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43 ltc_asn1_list decode[3];
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44
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45 LTC_ARGCHK(in != NULL);
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46 LTC_ARGCHK(out != NULL);
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47 LTC_ARGCHK(outlen != NULL);
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48 LTC_ARGCHK(key != NULL);
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49
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50 /* right key type? */
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51 if (key->type != PK_PRIVATE) {
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52 return CRYPT_PK_NOT_PRIVATE;
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53 }
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54
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55 /* decode to find out hash */
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56 LTC_SET_ASN1(decode, 0, LTC_ASN1_OBJECT_IDENTIFIER, hashOID, sizeof(hashOID)/sizeof(hashOID[0]));
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57
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58 if ((err = der_decode_sequence(in, inlen, decode, 1)) != CRYPT_OK) {
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59 return err;
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60 }
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61
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62 hash = find_hash_oid(hashOID, decode[0].size);
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63 if (hash_is_valid(hash) != CRYPT_OK) {
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64 return CRYPT_INVALID_PACKET;
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65 }
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66
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67 /* we now have the hash! */
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68
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69 /* allocate memory */
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70 pub_expt = XMALLOC(ECC_BUF_SIZE);
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71 ecc_shared = XMALLOC(ECC_BUF_SIZE);
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72 skey = XMALLOC(MAXBLOCKSIZE);
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73 if (pub_expt == NULL || ecc_shared == NULL || skey == NULL) {
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Matt Johnston <matt@ucc.asn.au>
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74 if (pub_expt != NULL) {
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Matt Johnston <matt@ucc.asn.au>
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75 XFREE(pub_expt);
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76 }
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Matt Johnston <matt@ucc.asn.au>
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77 if (ecc_shared != NULL) {
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Matt Johnston <matt@ucc.asn.au>
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78 XFREE(ecc_shared);
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Matt Johnston <matt@ucc.asn.au>
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79 }
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Matt Johnston <matt@ucc.asn.au>
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80 if (skey != NULL) {
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Matt Johnston <matt@ucc.asn.au>
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81 XFREE(skey);
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82 }
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Matt Johnston <matt@ucc.asn.au>
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83 return CRYPT_MEM;
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Matt Johnston <matt@ucc.asn.au>
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84 }
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
85 LTC_SET_ASN1(decode, 1, LTC_ASN1_OCTET_STRING, pub_expt, ECC_BUF_SIZE);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
86 LTC_SET_ASN1(decode, 2, LTC_ASN1_OCTET_STRING, skey, MAXBLOCKSIZE);
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 /* read the structure in now */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
89 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
90 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
91 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
92
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
93 /* import ECC key from packet */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
94 if ((err = ecc_import(decode[1].data, decode[1].size, &pubkey)) != CRYPT_OK) {
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
95 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
96 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
97
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
98 /* make shared key */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
99 x = ECC_BUF_SIZE;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
100 if ((err = ecc_shared_secret(key, &pubkey, ecc_shared, &x)) != CRYPT_OK) {
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
101 ecc_free(&pubkey);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
102 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
103 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
104 ecc_free(&pubkey);
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 y = MIN(ECC_BUF_SIZE, MAXBLOCKSIZE);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
107 if ((err = hash_memory(hash, ecc_shared, x, ecc_shared, &y)) != CRYPT_OK) {
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
108 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
109 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
110
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
111 /* 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
112 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
113 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
114 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
115 }
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 /* avoid buffer overflow */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
118 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
119 *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
120 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
121 goto LBL_ERR;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
122 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
123
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
124 /* Decrypt the key */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
125 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
126 out[x] = skey[x] ^ ecc_shared[x];
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
127 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
128 *outlen = x;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
129
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
130 err = CRYPT_OK;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
131 LBL_ERR:
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
132 #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
133 zeromem(pub_expt, ECC_BUF_SIZE);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
134 zeromem(ecc_shared, ECC_BUF_SIZE);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
135 zeromem(skey, MAXBLOCKSIZE);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
136 #endif
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
137
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
138 XFREE(pub_expt);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
139 XFREE(ecc_shared);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
140 XFREE(skey);
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
141
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
142 return err;
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
143 }
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
144
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
145 #endif
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
146
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
147 /* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_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
148 /* $Revision: 1.5 $ */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
149 /* $Date: 2006/06/16 21:53:41 $ */
0cbe8f6dbf9e propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
150