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/*************************************************
* DER Encoder Source File *
* (C) 1999-2005 The Botan Project *
*************************************************/
#include <botan/der_enc.h>
#include <botan/bigint.h>
#include <botan/bit_ops.h>
#include <botan/parsing.h>
namespace Botan {
namespace {
/*************************************************
* DER encode an ASN.1 type tag *
*************************************************/
SecureVector<byte> encode_tag(ASN1_Tag type_tag, ASN1_Tag class_tag)
{
if((class_tag | 0xE0) != 0xE0)
throw Encoding_Error("DER_Encoder: Invalid class tag " +
to_string(class_tag));
SecureVector<byte> encoded_tag;
if(type_tag <= 30)
encoded_tag.append((byte)(type_tag | class_tag));
else
{
u32bit blocks = high_bit(type_tag) + 6;
blocks = (blocks - (blocks % 7)) / 7;
encoded_tag.append(class_tag | 0x1F);
for(u32bit k = 0; k != blocks - 1; k++)
encoded_tag.append(0x80 | ((type_tag >> 7*(blocks-k-1)) & 0x7F));
encoded_tag.append(type_tag & 0x7F);
}
return encoded_tag;
}
/*************************************************
* DER encode an ASN.1 length field *
*************************************************/
SecureVector<byte> encode_length(u32bit length)
{
SecureVector<byte> encoded_length;
if(length <= 127)
encoded_length.append((byte)length);
else
{
const u32bit top_byte = significant_bytes(length);
encoded_length.append((byte)(0x80 | top_byte));
for(u32bit j = 4-top_byte; j != 4; j++)
encoded_length.append(get_byte(j, length));
}
return encoded_length;
}
/*************************************************
* A comparison functor for sorting SET objects *
*************************************************/
class DER_Cmp
{
public:
bool operator()(const MemoryRegion<byte>&,
const MemoryRegion<byte>&) const;
};
/*************************************************
* Compare two encodings, as specified by X.690 *
*************************************************/
bool DER_Cmp::operator()(const MemoryRegion<byte>& a,
const MemoryRegion<byte>& b) const
{
if(a.size() < b.size()) return true;
if(a.size() > b.size()) return false;
for(u32bit j = 0; j != a.size(); j++)
{
if(a[j] < b[j]) return true;
if(a[j] > b[j]) return false;
}
return false;
}
}
/*************************************************
* Return the encoded SEQUENCE/SET *
*************************************************/
SecureVector<byte> DER_Encoder::DER_Sequence::get_contents()
{
const ASN1_Tag real_class_tag = ASN1_Tag(class_tag | CONSTRUCTED);
SecureVector<byte> encoded_tag = encode_tag(type_tag, real_class_tag);
if(is_a_set)
{
std::sort(set_contents.begin(), set_contents.end(), DER_Cmp());
for(u32bit j = 0; j != set_contents.size(); j++)
contents.append(set_contents[j]);
set_contents.clear();
}
SecureVector<byte> encoded_length = encode_length(contents.size());
SecureVector<byte> retval;
retval.append(encoded_tag);
retval.append(encoded_length);
retval.append(contents);
contents.destroy();
return retval;
}
/*************************************************
* Add an encoded value to the SEQUENCE/SET *
*************************************************/
void DER_Encoder::DER_Sequence::add_bytes(const byte data[], u32bit length)
{
if(is_a_set)
{
set_contents.push_back(SecureVector<byte>(data, length));
}
else
contents.append(data, length);
}
/*************************************************
* Return the type and class taggings *
*************************************************/
ASN1_Tag DER_Encoder::DER_Sequence::tag_of() const
{
return ASN1_Tag(type_tag | class_tag);
}
/*************************************************
* DER_Sequence Constructor *
*************************************************/
DER_Encoder::DER_Sequence::DER_Sequence(ASN1_Tag t1, ASN1_Tag t2, bool b) :
type_tag(t1), class_tag(t2), is_a_set(b)
{
}
/*************************************************
* Return the encoded contents *
*************************************************/
SecureVector<byte> DER_Encoder::get_contents()
{
if(sequence_level != 0)
throw Invalid_State("DER_Encoder: Sequence hasn't been marked done");
SecureVector<byte> retval;
retval = contents;
contents.destroy();
return retval;
}
/*************************************************
* Start a new ASN.1 SEQUENCE/SET/EXPLICIT *
*************************************************/
void DER_Encoder::start_cons(ASN1_Tag type_tag, ASN1_Tag class_tag,
bool is_a_set)
{
sequence_level++;
subsequences.push_back(DER_Sequence(type_tag, class_tag, is_a_set));
}
/*************************************************
* Finish the current ASN.1 SEQUENCE/SET/EXPLICIT *
*************************************************/
void DER_Encoder::end_cons(ASN1_Tag type_tag, ASN1_Tag class_tag)
{
if(sequence_level == 0)
throw Invalid_State("DER_Encoder::end_cons: No such sequence");
sequence_level--;
if(subsequences[sequence_level].tag_of() != ASN1_Tag(type_tag | class_tag))
throw Invalid_Argument("DER_Encoder::end_cons: Tag mismatch");
SecureVector<byte> seq = subsequences[sequence_level].get_contents();
subsequences.pop_back();
add_raw_octets(seq);
}
/*************************************************
* Start a new ASN.1 SEQUENCE *
*************************************************/
void DER_Encoder::start_sequence(ASN1_Tag type_tag, ASN1_Tag class_tag)
{
start_cons(type_tag, class_tag, false);
}
/*************************************************
* Finish the current ASN.1 SEQUENCE *
*************************************************/
void DER_Encoder::end_sequence(ASN1_Tag type_tag, ASN1_Tag class_tag)
{
end_cons(type_tag, class_tag);
}
/*************************************************
* Start a new ASN.1 SET *
*************************************************/
void DER_Encoder::start_set(ASN1_Tag type_tag, ASN1_Tag class_tag)
{
start_cons(type_tag, class_tag, true);
}
/*************************************************
* Finish the current ASN.1 SET *
*************************************************/
void DER_Encoder::end_set(ASN1_Tag type_tag, ASN1_Tag class_tag)
{
end_cons(type_tag, class_tag);
}
/*************************************************
* Start a new ASN.1 SEQUENCE *
*************************************************/
void DER_Encoder::start_sequence()
{
start_sequence(SEQUENCE, UNIVERSAL);
}
/*************************************************
* Finish the current ASN.1 SEQUENCE *
*************************************************/
void DER_Encoder::end_sequence()
{
end_sequence(SEQUENCE, UNIVERSAL);
}
/*************************************************
* Start a new ASN.1 SET *
*************************************************/
void DER_Encoder::start_set()
{
start_set(SET, UNIVERSAL);
}
/*************************************************
* Finish the current ASN.1 SET *
*************************************************/
void DER_Encoder::end_set()
{
end_set(SET, UNIVERSAL);
}
/*************************************************
* Start a new ASN.1 EXPLICIT encoding *
*************************************************/
void DER_Encoder::start_explicit(ASN1_Tag type_tag, ASN1_Tag class_tag)
{
start_cons(type_tag, class_tag, false);
}
/*************************************************
* Finish the current ASN.1 EXPLICIT encoding *
*************************************************/
void DER_Encoder::end_explicit(ASN1_Tag type_tag, ASN1_Tag class_tag)
{
end_cons(type_tag, class_tag);
}
/*************************************************
* Write raw octets into the stream *
*************************************************/
void DER_Encoder::add_raw_octets(const MemoryRegion<byte>& octets)
{
add_raw_octets(octets.begin(), octets.size());
}
/*************************************************
* Write raw octets into the stream *
*************************************************/
void DER_Encoder::add_raw_octets(const byte octets[], u32bit length)
{
if(sequence_level == 0)
contents.append(octets, length);
else
subsequences[sequence_level-1].add_bytes(octets, length);
}
/*************************************************
* Write the encoding of the octet(s) *
*************************************************/
void DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag,
const byte rep[], u32bit length)
{
SecureVector<byte> encoded_tag = encode_tag(type_tag, class_tag);
SecureVector<byte> encoded_length = encode_length(length);
SecureVector<byte> buffer;
buffer.append(encoded_tag);
buffer.append(encoded_length);
buffer.append(rep, length);
add_raw_octets(buffer);
}
/*************************************************
* Write the encoding of the octet(s) *
*************************************************/
void DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag,
const MemoryRegion<byte>& rep_buf)
{
const byte* rep = rep_buf.begin();
const u32bit rep_len = rep_buf.size();
add_object(type_tag, class_tag, rep, rep_len);
}
/*************************************************
* Write the encoding of the octet(s) *
*************************************************/
void DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag,
const std::string& rep_str)
{
const byte* rep = (const byte*)rep_str.c_str();
const u32bit rep_len = rep_str.size();
add_object(type_tag, class_tag, rep, rep_len);
}
/*************************************************
* Write the encoding of the octet *
*************************************************/
void DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag, byte rep)
{
add_object(type_tag, class_tag, &rep, 1);
}
/*************************************************
* DER_Encoder Constructor *
*************************************************/
DER_Encoder::DER_Encoder()
{
sequence_level = 0;
}
}
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