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/*
* Copyright (c) 2018 SURFnet bv
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*****************************************************************************
DerUtil.h
DER encoding convenience functions
*****************************************************************************/
#include "config.h"
#include "DerUtil.h"
// Convert a raw ByteString to a DER encoded octet string
ByteString DERUTIL::raw2Octet(const ByteString& byteString)
{
ByteString header;
size_t len = byteString.size();
// Definite, short
if (len < 0x80)
{
header.resize(2);
header[0] = (unsigned char)0x04;
header[1] = (unsigned char)(len & 0x7F);
}
// Definite, long
else
{
// Count significate bytes
size_t bytes = sizeof(size_t);
for(; bytes > 0; bytes--)
{
size_t value = len >> ((bytes - 1) * 8);
if (value & 0xFF) break;
}
// Set header data
header.resize(2 + bytes);
header[0] = (unsigned char)0x04;
header[1] = (unsigned char)(0x80 | bytes);
for (size_t i = 1; i <= bytes; i++)
{
header[2+bytes-i] = (unsigned char) (len & 0xFF);
len >>= 8;
}
}
return header + byteString;
}
// Convert a DER encoded octet string to a raw ByteString
ByteString DERUTIL::octet2Raw(const ByteString& byteString)
{
ByteString rv;
ByteString repr = byteString;
size_t len = repr.size();
size_t controlOctets = 2;
if (len < controlOctets)
{
ERROR_MSG("Undersized octet string");
return rv;
}
if (repr[0] != 0x04)
{
ERROR_MSG("ByteString is not an octet string");
return rv;
}
// Definite, short
if (repr[1] < 0x80)
{
if (repr[1] != (len - controlOctets))
{
if (repr[1] < (len - controlOctets))
{
ERROR_MSG("Underrun octet string");
}
else
{
ERROR_MSG("Overrun octet string");
}
return rv;
}
}
// Definite, long
else
{
size_t lengthOctets = repr[1] & 0x7f;
controlOctets += lengthOctets;
if (controlOctets >= repr.size())
{
ERROR_MSG("Undersized octet string");
return rv;
}
ByteString length(&repr[2], lengthOctets);
if (length.long_val() != (len - controlOctets))
{
if (length.long_val() < (len - controlOctets))
{
ERROR_MSG("Underrun octet string");
}
else
{
ERROR_MSG("Overrun octet string");
}
return rv;
}
}
return repr.substr(controlOctets, len - controlOctets);
}
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