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/*************************************************
* X.509 Public Key Source File *
* (C) 1999-2005 The Botan Project *
*************************************************/
#include <botan/x509_key.h>
#include <botan/filters.h>
#include <botan/asn1_obj.h>
#include <botan/pk_algs.h>
#include <botan/oids.h>
#include <botan/pem.h>
#include <memory>
namespace Botan {
/*************************************************
* Compute the key id *
*************************************************/
u64bit X509_PublicKey::key_id() const
{
Pipe pipe(new Hash_Filter("SHA-1", 8));
pipe.start_msg();
pipe.write(algo_name());
pipe.write(DER_encode_pub());
pipe.write(DER_encode_params());
pipe.end_msg();
u64bit hash = 0;
for(u32bit j = 0; j != 8; j++)
{
byte next = 0;
if(pipe.read(next) != 1)
throw Internal_Error("X509_PublicKey::key_id: No more hash bits");
hash = (hash << 8) | next;
}
return hash;
}
namespace X509 {
namespace {
/*************************************************
* Extract the fields of a subjectPublicKeyInfo *
*************************************************/
void X509_extract_info(DataSource& source, AlgorithmIdentifier& alg_id,
MemoryVector<byte>& key)
{
BER_Decoder decoder(source);
BER_Decoder sequence = BER::get_subsequence(decoder);
BER::decode(sequence, alg_id);
BER::decode(sequence, key, BIT_STRING);
sequence.verify_end();
}
}
/*************************************************
* DER or PEM encode a X.509 public key *
*************************************************/
void encode(const X509_PublicKey& key, Pipe& pipe, X509_Encoding encoding)
{
DER_Encoder encoder;
AlgorithmIdentifier alg_id(key.get_oid(), key.DER_encode_params());
encoder.start_sequence();
DER::encode(encoder, alg_id);
DER::encode(encoder, key.DER_encode_pub(), BIT_STRING);
encoder.end_sequence();
MemoryVector<byte> der = encoder.get_contents();
if(encoding == PEM)
pipe.write(PEM_Code::encode(der, "PUBLIC KEY"));
else
pipe.write(der);
}
/*************************************************
* PEM encode a X.509 public key *
*************************************************/
std::string PEM_encode(const X509_PublicKey& key)
{
Pipe pem;
pem.start_msg();
encode(key, pem, PEM);
pem.end_msg();
return pem.read_all_as_string();
}
/*************************************************
* Extract a public key and return it *
*************************************************/
X509_PublicKey* load_key(DataSource& source)
{
try {
AlgorithmIdentifier alg_id;
MemoryVector<byte> key;
if(BER::maybe_BER(source) && !PEM_Code::matches(source))
X509_extract_info(source, alg_id, key);
else
{
DataSource_Memory ber(
PEM_Code::decode_check_label(source, "PUBLIC KEY")
);
X509_extract_info(ber, alg_id, key);
}
if(key.is_empty())
throw Decoding_Error("X.509 public key decoding failed");
const std::string alg_name = OIDS::lookup(alg_id.oid);
if(alg_name == "")
throw Decoding_Error("Unknown algorithm OID: " +
alg_id.oid.as_string());
std::auto_ptr<X509_PublicKey> key_obj(get_public_key(alg_name));
if(!key_obj.get())
throw Decoding_Error("Unknown PK algorithm/OID: " + alg_name + ", " +
alg_id.oid.as_string());
Pipe output;
output.process_msg(alg_id.parameters);
output.process_msg(key);
key_obj->BER_decode_params(output);
output.set_default_msg(1);
key_obj->BER_decode_pub(output);
return key_obj.release();
}
catch(Decoding_Error)
{
throw Decoding_Error("X.509 public key decoding failed");
}
}
/*************************************************
* Extract a public key and return it *
*************************************************/
X509_PublicKey* load_key(const std::string& fsname)
{
DataSource_Stream source(fsname, true);
return X509::load_key(source);
}
/*************************************************
* Extract a public key and return it *
*************************************************/
X509_PublicKey* load_key(const MemoryRegion<byte>& mem)
{
DataSource_Memory source(mem);
return X509::load_key(source);
}
/*************************************************
* Make a copy of this public key *
*************************************************/
X509_PublicKey* copy_key(const X509_PublicKey& key)
{
Pipe bits;
bits.start_msg();
X509::encode(key, bits, RAW_BER);
bits.end_msg();
DataSource_Memory source(bits.read_all());
return X509::load_key(source);
}
/*************************************************
* Find the allowable key constraints *
*************************************************/
Key_Constraints find_constraints(const X509_PublicKey& pub_key,
Key_Constraints limits)
{
const X509_PublicKey* key = &pub_key;
u32bit constraints = 0;
if(dynamic_cast<const PK_Encrypting_Key*>(key))
constraints |= KEY_ENCIPHERMENT;
if(dynamic_cast<const PK_Key_Agreement_Key*>(key))
constraints |= KEY_AGREEMENT;
if(dynamic_cast<const PK_Verifying_wo_MR_Key*>(key) ||
dynamic_cast<const PK_Verifying_with_MR_Key*>(key))
constraints |= DIGITAL_SIGNATURE | NON_REPUDIATION;
if(limits)
constraints &= limits;
return Key_Constraints(constraints);
}
}
}
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