keystrings-decrypter is a simple tool for decrypting *_keystrings.dat files from TouchWiz.

The keystrings.dat file is an encrypted XML file describing various dialer codes and which Android packages are associated with them. It consists of 64-byte RSA-encrypted blocks without any headers or padding. The RSA modulus and private exponent are stored in assets/mod_pri_key.txt and assets/exp_pri_key.txt within /system/app/DRParser.apk from any TouchWiz ROM.

The Python script does the RSA decryption itself and has no dependencies other than Python 3 itself. To decrypt the keystrings file, first extract the RSA modulus and private exponent files described above from DRParser.apk. Then run the script as follows:

python3 keystrings-decrypter.py \
    --rsa-mod-file /path/to/mod_pri_key.txt \
    --rsa-priv-exp-file /path/to/exp_pri_key.txt \
    -i /path/to/keystrings.dat \
    -o output.xml

The modulus and exponent can also be specified directly via the --rsa-mod and --rsa-priv-exp options. If -i is omitted, input is taken from stdin. Similarly, if -o is omitted, the decrypted file is output to stdout.