1 files changed, 98 insertions, 0 deletions
diff --git a/doc/examples/dsa_ver.cpp b/doc/examples/dsa_ver.cpp
new file mode 100644
index 000000000..a666259c1
--- /dev/null
+++ b/doc/examples/dsa_ver.cpp
@@ -0,0 +1,98 @@
+/*
+* (C) 2009 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+/*
+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: take the IEEE 1363
+signature format, encoded into base64 with a trailing newline.
+*/
+
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <cstdlib>
+#include <string>
+#include <memory>
+
+#include <botan/botan.h>
+#include <botan/pubkey.h>
+#include <botan/dsa.h>
+using namespace Botan;
+
+namespace {
+
+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;
+      }
+
+   Botan::LibraryInitializer init;
+
+   std::ifstream message(argv[2], std::ios::binary);
+   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);
+
+      PK_Verifier ver(*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;
+   }