function decrypt(data, password, success, error) {

    var modes = [ new Crypto.mode.CBC(Crypto.pad.iso10126), new Crypto.mode.OFB(Crypto.pad.iso7816), new Crypto.mode.CBC(Crypto.pad.NoPadding), new Crypto.mode.CBC(Crypto.pad.ZeroPadding)];

    for (var mi = 0; mi < modes.length; ++mi) {
        var mode = modes[mi];

        for (var i = 10; i < 20; ++i) {
            try {
                var decoded = Crypto.AES.decrypt(data, password, { mode: mode, iterations : i });

                if (decoded != null && decoded.length > 0) {
                    if (success(decoded)) {
                        return decoded;
                    };
                };
            } catch (e) {
                console.log(e);
            }
        }

        for (var i = 0; i < 10; ++i) {
            try {
                var decoded = Crypto.AES.decrypt(data, password, { mode: mode, iterations : i });

                if (decoded != null && decoded.length > 0) {
                    if (success(decoded)) {
                        return decoded;
                    };
                };
            } catch (e) {
                console.log(e);
            }
        }
    }

    if (error != null)
        error();

    return null;
}

function do_decrypt() {
    try {
       document.getElementById('error').innerHTML = '';

       var encrypted = document.getElementById('enc-json').value;

       if (encrypted == null || encrypted.length == 0)
            throw 'You must copy and paste your encrypted backup into the first text area';

        var password = document.getElementById('password').value;

        if (password == null || password.length == 0) {
            throw 'You must enter a password';
        }

        var decrypted = decrypt(encrypted, password, function(decrypted) {
            try {
                obj = JSON.parse(decrypted);

                return (obj != null);
            } catch (e) {
                console.log(e);
                return false;
            };
        });

        if (decrypted == null || decrypted.length == 0)
            throw 'No backup returned';

        var obj = JSON.parse(decrypted);

        if (obj.double_encryption) {
            var pass = prompt("Please enter your second password", null);

            for (var i = 0; i < obj.keys.length; ++i) {
                obj.keys[i].priv = decrypt(obj.keys[i].priv, obj.sharedKey + pass, isBase58);
            }

            decrypted = JSON.stringify(obj);
        }

        var ul = document.getElementById('ul-keys');
        for (var i = 0; i < obj.keys.length; ++i) {
            var li = document.createElement('li');
            li.innerHTML = '<b>'+ obj.keys[i].addr + '</b>      -       ' + obj.keys[i].priv;
            ul.appendChild(li);
        }

        document.getElementById('plain-json').value = decrypted;

    } catch(e) {
        console.log(e);

        document.getElementById('error').innerHTML = 'Unable to decrypt backup ' + e;
    }
}