Recover lost jabber passwords in Psi’s config files

Imagine you have saved the password for your jabber account in Psi and now you can’t memorize. Fourtunately the encryption of Psi’ config file can be reversed.

The password is saved in file config.xml in an encrypted way. You can
recover it with the following code which I copied from psi’s source
code:

#include <qstring.h>
#include <iostream>

int hexChar2int(char c)
{
        if(c >= 'A' && c <= 'F')
                return c - 'A' + 10;
        else if(c >= 'a' && c <= 'f')
                return c - 'a' + 10;
        else if(c >= '0' && c <= '9')
                return c - '0';

        return 0;
}

QString decodePassword(const QString &pass, const QString &key)
{
        QString result;
        unsigned int n1, n2;

        if(key.length() == 0)
                return pass;

        for(n1 = 0, n2 = 0; n1 < pass.length(); n1 += 4) {
                ushort x = 0;
                if(n1 + 4 > pass.length())
                        break;
                x += hexChar2int(pass.at(n1))*4096;
                x += hexChar2int(pass.at(n1+1))*256;
                x += hexChar2int(pass.at(n1+2))*16;
                x += hexChar2int(pass.at(n1+3));
                QChar c(x ^ key.at(n2++).unicode());
                result += c;
                if(n2 >= key.length())
                        n2 = 0;
        }
        return result;
}

int main()
{
    QString password = "aaa000000000000000000000000000000000000000000";
    QString key = "id@jabber.org";
    QString out = decodePassword(password,key);
    std::cout << out << std::endl;
}

Compile it with

$ g++ -I$QTDIR/include -L$QTDIR/lib decode.cc -lqt-mt

My friend Dominik made some small modifications to the code above and added a Makefile. You can download the resulting archive PsiDescramble.tar.gz.