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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
#include "tomcrypt.h"
/**
@file der_decode_object_identifier.c
ASN.1 DER, Decode Object Identifier, Tom St Denis
*/
#ifdef LTC_DER
/**
Decode OID data and store the array of integers in words
@param in The OID DER encoded data
@param inlen The length of the OID data
@param words [out] The destination of the OID words
@param outlen [in/out] The number of OID words
@return CRYPT_OK if successful
*/
int der_decode_object_identifier(const unsigned char *in, unsigned long inlen,
unsigned long *words, unsigned long *outlen)
{
unsigned long x, y, t, len;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(words != NULL);
LTC_ARGCHK(outlen != NULL);
/* header is at least 3 bytes */
if (inlen < 3) {
return CRYPT_INVALID_PACKET;
}
/* must be room for at least two words */
if (*outlen < 2) {
return CRYPT_BUFFER_OVERFLOW;
}
/* decode the packet header */
x = 0;
if ((in[x++] & 0x1F) != 0x06) {
return CRYPT_INVALID_PACKET;
}
/* get the length */
if (in[x] < 128) {
len = in[x++];
} else {
if (in[x] < 0x81 || in[x] > 0x82) {
return CRYPT_INVALID_PACKET;
}
y = in[x++] & 0x7F;
len = 0;
while (y--) {
len = (len << 8) | (unsigned long)in[x++];
}
}
if (len < 1 || (len + x) > inlen) {
return CRYPT_INVALID_PACKET;
}
/* decode words */
y = 0;
t = 0;
while (len--) {
t = (t << 7) | (in[x] & 0x7F);
if (!(in[x++] & 0x80)) {
/* store t */
if (y >= *outlen) {
return CRYPT_BUFFER_OVERFLOW;
}
if (y == 0) {
words[0] = t / 40;
words[1] = t % 40;
y = 2;
} else {
words[y++] = t;
}
t = 0;
}
}
*outlen = y;
return CRYPT_OK;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/object_identifier/der_decode_object_identifier.c,v $ */
/* $Revision: 1.6 $ */
/* $Date: 2006/12/28 01:27:24 $ */
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