Add a password hashing example. It uses PBKDF2/SHA-1 with 10000 iterations,

a 48-bit seed, and a 96-bit hash. The example can both create new hashes
and confirm existing ones.

1 files changed, 76 insertions, 0 deletions

diff --git a/doc/examples/passhash.cpp b/doc/examples/passhash.cpp
new file mode 100644
index 000000000..19b4abc40
--- /dev/null
+++ b/doc/examples/passhash.cpp
@@ -0,0 +1,76 @@
+#include <botan/botan.h>
+#include <botan/pkcs5.h>
+#include <iostream>
+
+using namespace Botan;
+
+std::string password_hash(const std::string& pass);
+bool password_hash_ok(const std::string& pass, const std::string& hash);
+
+int main(int argc, char* argv[])
+   {
+   if(argc != 2 && argc != 3)
+      {
+      std::cerr << "Usage: " << argv[0] << " password\n";
+      std::cerr << "Usage: " << argv[0] << " password hash\n";
+      return 1;
+      }
+
+   try
+      {
+      LibraryInitializer init;
+
+      if(argc == 2)
+         std::cout << "H('" << argv[1] << "') = " << password_hash(argv[1]) << '\n';
+      else
+         {
+         bool ok = password_hash_ok(argv[1], argv[2]);
+         if(ok)
+            std::cout << "Password and hash match\n";
+         else
+            std::cout << "Password and hash do not match\n";
+         }
+      }
+   catch(std::exception& e)
+      {
+      std::cerr << e.what() << '\n';
+      return 1;
+      }
+   return 0;
+   }
+
+std::string password_hash(const std::string& pass)
+   {
+   PKCS5_PBKDF2 kdf("SHA-1");
+
+   kdf.set_iterations(10000);
+   kdf.new_random_salt(6); // 48 bits
+
+   Pipe pipe(new Base64_Encoder);
+   pipe.start_msg();
+   pipe.write(kdf.current_salt());
+   pipe.write(kdf.derive_key(12, pass).bits_of());
+   pipe.end_msg();
+
+   return pipe.read_all_as_string();
+   }
+
+bool password_hash_ok(const std::string& pass, const std::string& hash)
+   {
+   Pipe pipe(new Base64_Decoder);
+   pipe.start_msg();
+   pipe.write(hash);
+   pipe.end_msg();
+
+   SecureVector<byte> hash_bin = pipe.read_all();
+
+   PKCS5_PBKDF2 kdf("SHA-1");
+
+   kdf.set_iterations(10000);
+   kdf.change_salt(hash_bin, 6);
+
+   SecureVector<byte> cmp = kdf.derive_key(12, pass).bits_of();
+
+   return same_mem(cmp.begin(), hash_bin.begin() + 6, 12);
+   }
+