This is weird. I just tried to encrypt value with 18.104.22.168 version. And it was successfully decrypted with latest version using key e806f69e7aea3ee30fe27a6abfae967f and 4444 key for ObscuredString.EncryptDecrypt() method as I described above. Could you please confirm you use both e806f69e7aea3ee30fe27a6abfae967f and 4444? And you set new crypto key before accessing prefs? I'd be glad to contact with you via skype for higher productivity and help you to resolve this issue. Feel free to add me there (dmitry.you).