JCryptor
JCryptor is an encrypting tool based on the Caesar-cipher.
...ROT13 can be decrypted by encrypting it again with ROT13. Even today this simple method is used by authorities to protect documents from unintentional reading.
--UPDATE--
[25.01.14] Release 1.0 (final)
-- Bugfixes
[05.05.12] Release 0.2
-- implements polyalphabeticel substitution