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comparison libtomcrypt/src/pk/asn1/der/object_identifier/der_encode_object_identifier.c @ 399:a707e6148060

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merge of '5fdf69ca60d1683cdd9f4c2595134bed26394834' and '6b61c50f4cf888bea302ac8fcf5dbb573b443251'
author Matt Johnston <matt@ucc.asn.au>
date Sat, 03 Feb 2007 08:20:34 +0000
parents 0cbe8f6dbf9e
children f849a5ca2efc
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394:17d097fc111c 399:a707e6148060
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, [email protected], http://libtomcrypt.com
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file der_encode_object_identifier.c
15 ASN.1 DER, Encode Object Identifier, Tom St Denis
16 */
17
18 #ifdef LTC_DER
19 /**
20 Encode an OID
21 @param words The words to encode (upto 32-bits each)
22 @param nwords The number of words in the OID
23 @param out [out] Destination of OID data
24 @param outlen [in/out] The max and resulting size of the OID
25 @return CRYPT_OK if successful
26 */
27 int der_encode_object_identifier(unsigned long *words, unsigned long nwords,
28 unsigned char *out, unsigned long *outlen)
29 {
30 unsigned long i, x, y, z, t, mask, wordbuf;
31 int err;
32
33 LTC_ARGCHK(words != NULL);
34 LTC_ARGCHK(out != NULL);
35 LTC_ARGCHK(outlen != NULL);
36
37 /* check length */
38 if ((err = der_length_object_identifier(words, nwords, &x)) != CRYPT_OK) {
39 return err;
40 }
41 if (x > *outlen) {
42 *outlen = x;
43 return CRYPT_BUFFER_OVERFLOW;
44 }
45
46 /* compute length to store OID data */
47 z = 0;
48 wordbuf = words[0] * 40 + words[1];
49 for (y = 1; y < nwords; y++) {
50 t = der_object_identifier_bits(wordbuf);
51 z += t/7 + ((t%7) ? 1 : 0) + (wordbuf == 0 ? 1 : 0);
52 if (y < nwords - 1) {
53 wordbuf = words[y + 1];
54 }
55 }
56
57 /* store header + length */
58 x = 0;
59 out[x++] = 0x06;
60 if (z < 128) {
61 out[x++] = (unsigned char)z;
62 } else if (z < 256) {
63 out[x++] = 0x81;
64 out[x++] = (unsigned char)z;
65 } else if (z < 65536UL) {
66 out[x++] = 0x82;
67 out[x++] = (unsigned char)((z>>8)&255);
68 out[x++] = (unsigned char)(z&255);
69 } else {
70 return CRYPT_INVALID_ARG;
71 }
72
73 /* store first byte */
74 wordbuf = words[0] * 40 + words[1];
75 for (i = 1; i < nwords; i++) {
76 /* store 7 bit words in little endian */
77 t = wordbuf & 0xFFFFFFFF;
78 if (t) {
79 y = x;
80 mask = 0;
81 while (t) {
82 out[x++] = (unsigned char)((t & 0x7F) | mask);
83 t >>= 7;
84 mask |= 0x80; /* upper bit is set on all but the last byte */
85 }
86 /* now swap bytes y...x-1 */
87 z = x - 1;
88 while (y < z) {
89 t = out[y]; out[y] = out[z]; out[z] = (unsigned char)t;
90 ++y;
91 --z;
92 }
93 } else {
94 /* zero word */
95 out[x++] = 0x00;
96 }
97
98 if (i < nwords - 1) {
99 wordbuf = words[i + 1];
100 }
101 }
102
103 *outlen = x;
104 return CRYPT_OK;
105 }
106
107 #endif
108
109 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/object_identifier/der_encode_object_identifier.c,v $ */
110 /* $Revision: 1.6 $ */
111 /* $Date: 2006/12/04 21:34:03 $ */