/*

* Keypair Checks

* (C) 1999-2010 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include <botan/keypair.h>

#include <botan/pubkey.h>

#include <botan/rng.h>

namespace Botan {

namespace KeyPair {

/*

* Check an encryption key pair for consistency

*/

bool encryption_consistency_check(RandomNumberGenerator& rng,

                                  const Private_Key& private_key,

                                  const Public_Key& public_key,

                                  const std::string& padding)

   {

   PK_Encryptor_EME encryptor(public_key, rng, padding);

   PK_Decryptor_EME decryptor(private_key, rng, padding);

   /*

   Weird corner case, if the key is too small to encrypt anything at

   all. This can happen with very small RSA keys with PSS

   */

   if(encryptor.maximum_input_size() == 0)

      return true;

   std::vector<uint8_t> plaintext =

      unlock(rng.random_vec(encryptor.maximum_input_size() - 1));

   std::vector<uint8_t> ciphertext = encryptor.encrypt(plaintext, rng);

   if(ciphertext == plaintext)

      return false;

   std::vector<uint8_t> decrypted = unlock(decryptor.decrypt(ciphertext));

   return (plaintext == decrypted);

   }

/*

* Check a signature key pair for consistency

*/

bool signature_consistency_check(RandomNumberGenerator& rng,

                                 const Private_Key& private_key,

                                 const Public_Key& public_key,

                                 const std::string& padding)

   {

   PK_Signer signer(private_key, rng, padding);

   PK_Verifier verifier(public_key, padding);

   std::vector<uint8_t> message(32);

   rng.randomize(message.data(), message.size());

   std::vector<uint8_t> signature;

   try

      {

      signature = signer.sign_message(message, rng);

      }

   catch(Encoding_Error&)

      {

      return false;

      }

   if(!verifier.verify_message(message, signature))

      return false;

   // Now try to check a corrupt signature, ensure it does not succeed

   ++signature[0];

   if(verifier.verify_message(message, signature))

      return false;

   return true;

   }

}

}