Mercurial > dropbear
diff src/pk/asn1/der/octet/der_decode_octet_string.c @ 209:39d5d58461d6 libtomcrypt-orig LTC_1.05
Import of libtomcrypt 1.05
author | Matt Johnston <matt@ucc.asn.au> |
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date | Wed, 06 Jul 2005 03:53:40 +0000 |
parents | |
children | d5faf4814ddb |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/pk/asn1/der/octet/der_decode_octet_string.c Wed Jul 06 03:53:40 2005 +0000 @@ -0,0 +1,90 @@ +/* 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, [email protected], http://libtomcrypt.org + */ +#include "tomcrypt.h" + +/** + @file der_decode_octet_string.c + ASN.1 DER, encode a OCTET STRING, Tom St Denis +*/ + + +#ifdef LTC_DER + +/** + Store a OCTET STRING + @param in The DER encoded OCTET STRING + @param inlen The size of the DER OCTET STRING + @param out [out] The array of octets stored (one per char) + @param outlen [in/out] The number of octets stored + @return CRYPT_OK if successful +*/ +int der_decode_octet_string(const unsigned char *in, unsigned long inlen, + unsigned char *out, unsigned long *outlen) +{ + unsigned long x, y, len; + + LTC_ARGCHK(in != NULL); + LTC_ARGCHK(out != NULL); + LTC_ARGCHK(outlen != NULL); + + /* must have header at least */ + if (inlen < 2) { + return CRYPT_INVALID_PACKET; + } + + /* check for 0x04 */ + if ((in[0] & 0x1F) != 0x04) { + return CRYPT_INVALID_PACKET; + } + x = 1; + + /* decode the length */ + if (in[x] & 0x80) { + /* valid # of bytes in length are 1,2,3 */ + y = in[x] & 0x7F; + if ((y == 0) || (y > 3) || ((x + y) > inlen)) { + return CRYPT_INVALID_PACKET; + } + + /* read the length in */ + len = 0; + ++x; + while (y--) { + len = (len << 8) | in[x++]; + } + } else { + len = in[x++] & 0x7F; + } + + /* is it too long? */ + if (len > *outlen) { + return CRYPT_BUFFER_OVERFLOW; + } + + if (len + x > inlen) { + return CRYPT_INVALID_PACKET; + } + + /* read the data */ + for (y = 0; y < len; y++) { + out[y] = in[x++]; + } + + *outlen = y; + + return CRYPT_OK; +} + +#endif + +/* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/octet/der_decode_octet_string.c,v $ */ +/* $Revision: 1.1 $ */ +/* $Date: 2005/05/16 15:08:11 $ */