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/*
Grab an DSA public key from the file given as an argument, grab a signature
from another file, and verify the message (which, suprise, is also in a file).
The signature format isn't particularly standard, but it's not bad. It's simply
the IEEE 1363 signature format, encoded into base64 with a trailing newline
Written by Jack Lloyd (lloyd@randombit.net), August 5, 2002
Updated to use X.509 format keys, October 21, 2002
This file is in the public domain
*/
#include <iostream>
#include <iomanip>
#include <fstream>
#include <cstdlib>
#include <string>
#include <memory>
#include <botan/botan.h>
#include <botan/look_pk.h>
#include <botan/dsa.h>
using namespace Botan;
SecureVector<byte> b64_decode(const std::string& in)
{
Pipe pipe(new Base64_Decoder);
pipe.process_msg(in);
return pipe.read_all();
}
int main(int argc, char* argv[])
{
if(argc != 4)
{
std::cout << "Usage: " << argv[0]
<< " keyfile messagefile sigfile" << std::endl;
return 1;
}
std::ifstream message(argv[2]);
if(!message)
{
std::cout << "Couldn't read the message file." << std::endl;
return 1;
}
std::ifstream sigfile(argv[3]);
if(!sigfile)
{
std::cout << "Couldn't read the signature file." << std::endl;
return 1;
}
try {
std::string sigstr;
getline(sigfile, sigstr);
std::auto_ptr<X509_PublicKey> key(X509::load_key(argv[1]));
DSA_PublicKey* dsakey = dynamic_cast<DSA_PublicKey*>(key.get());
if(!dsakey)
{
std::cout << "The loaded key is not a DSA key!\n";
return 1;
}
SecureVector<byte> sig = b64_decode(sigstr);
std::auto_ptr<PK_Verifier> ver(get_pk_verifier(*dsakey, "EMSA1(SHA-1)"));
DataSource_Stream in(message);
byte buf[4096] = { 0 };
while(u32bit got = in.read(buf, sizeof(buf)))
ver->update(buf, got);
bool ok = ver->check_signature(sig);
if(ok)
std::cout << "Signature verified\n";
else
std::cout << "Signature did NOT verify\n";
}
catch(std::exception& e)
{
std::cout << "Exception caught: " << e.what() << std::endl;
return 1;
}
return 0;
}
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