1 files changed, 83 insertions, 0 deletions
diff --git a/botan/doc/examples/dsa_sign.cpp b/botan/doc/examples/dsa_sign.cpp
new file mode 100644
index 0000000..caf0503
--- /dev/null
+++ b/botan/doc/examples/dsa_sign.cpp
@@ -0,0 +1,83 @@
+/*
+Decrypt an encrypted DSA private key. Then use that key to sign a message.
+
+Written by Jack Lloyd (lloyd@randombit.net), August 5, 2002
+   Updated to use X.509 and PKCS #8 format keys, October 21, 2002
+
+This file is in the public domain
+*/
+
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <string>
+#include <memory>
+
+#include <botan/botan.h>
+#include <botan/look_pk.h>
+#include <botan/dsa.h>
+using namespace Botan;
+
+const std::string SUFFIX = ".sig";
+
+int main(int argc, char* argv[])
+   {
+   if(argc != 4)
+      {
+      std::cout << "Usage: " << argv[0] << " keyfile messagefile passphrase"
+                << std::endl;
+      return 1;
+      }
+
+   Botan::LibraryInitializer init;
+
+   try {
+      std::string passphrase(argv[3]);
+
+      std::ifstream message(argv[2]);
+      if(!message)
+         {
+         std::cout << "Couldn't read the message file." << std::endl;
+         return 1;
+         }
+
+      std::string outfile = argv[2] + SUFFIX;
+      std::ofstream sigfile(outfile.c_str());
+      if(!sigfile)
+         {
+         std::cout << "Couldn't write the signature to "
+                   << outfile << std::endl;
+         return 1;
+         }
+
+      AutoSeeded_RNG rng;
+
+      std::auto_ptr<PKCS8_PrivateKey> key(
+         PKCS8::load_key(argv[1], rng, passphrase)
+         );
+
+      DSA_PrivateKey* dsakey = dynamic_cast<DSA_PrivateKey*>(key.get());
+
+      if(!dsakey)
+         {
+         std::cout << "The loaded key is not a DSA key!\n";
+         return 1;
+         }
+
+      PK_Signer signer(*dsakey, get_emsa("EMSA1(SHA-1)"));
+
+      DataSource_Stream in(message);
+      byte buf[4096] = { 0 };
+      while(u32bit got = in.read(buf, sizeof(buf)))
+         signer.update(buf, got);
+
+      Pipe pipe(new Base64_Encoder);
+      pipe.process_msg(signer.signature(rng));
+      sigfile << pipe.read_all_as_string() << std::endl;
+   }
+   catch(std::exception& e)
+      {
+      std::cout << "Exception caught: " << e.what() << std::endl;
+      }
+   return 0;
+   }