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/*
* Copyright (C) 2013 Andreas Steffen
* HSR Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "dnskey_encoder.h"
#include <utils/debug.h>
/**
* Encode an RSA public key in DNSKEY format (RFC 3110)
*/
static bool build_pub(chunk_t *encoding, va_list args)
{
chunk_t n, e, pubkey;
size_t exp_len;
u_char *pos;
if (cred_encoding_args(args, CRED_PART_RSA_MODULUS, &n,
CRED_PART_RSA_PUB_EXP, &e, CRED_PART_END))
{
/* remove leading zeros in exponent and modulus */
while (*e.ptr == 0)
{
e = chunk_skip(e, 1);
}
while (*n.ptr == 0)
{
n = chunk_skip(n, 1);
}
if (e.len < 256)
{
/* exponent length fits into a single octet */
exp_len = 1;
pubkey = chunk_alloc(exp_len + e.len + n.len);
pubkey.ptr[0] = (char)e.len;
}
else if (e.len < 65536)
{
/* exponent length fits into two octets preceded by zero octet */
exp_len = 3;
pubkey = chunk_alloc(exp_len + e.len + n.len);
pubkey.ptr[0] = 0x00;
htoun16(pubkey.ptr + 1, e.len);
}
else
{
/* exponent length is too large */
return FALSE;
}
/* copy exponent and modulus and convert to base64 format */
pos = pubkey.ptr + exp_len;
memcpy(pos, e.ptr, e.len);
pos += e.len;
memcpy(pos, n.ptr, n.len);
*encoding = chunk_to_base64(pubkey, NULL);
chunk_free(&pubkey);
return TRUE;
}
return FALSE;
}
/**
* See header.
*/
bool dnskey_encoder_encode(cred_encoding_type_t type, chunk_t *encoding,
va_list args)
{
switch (type)
{
case PUBKEY_DNSKEY:
return build_pub(encoding, args);
default:
return FALSE;
}
}
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