GnuPG encrypted data storage

YKManager.py

import sys
import os
import pickle
import subprocess

if __name__ == "__main__":
    def dictString(dictionary: dict, level=0, seperator=">", whiteSpaceAfterSeperator=True, globalPrefix="") -> str:
        ret = ""
        for v in dictionary.keys():
            ret += globalPrefix + seperator * level
            if whiteSpaceAfterSeperator and level > 0:
                ret += " "
            if isinstance(dictionary[v], dict):
                ret += f"{v}\n{dictString(dictionary[v], level + 1, seperator, whiteSpaceAfterSeperator, globalPrefix)}"
            else:
                ret += f"{v}: {dictionary[v]}\n"
        return ret

    cmd = sys.argv[1].lower() if len(sys.argv) > 1 else ""

    if cmd in ["edit", "known", "remove", "show"]:
        if os.path.exists("Data"):
            gpgDecryption = subprocess.Popen(
                ["gpg", "--quiet", "--decrypt", "Data"],
                stdout=subprocess.PIPE,
                bufsize=0
            )
            try:
                KeyData = pickle.load(gpgDecryption.stdout)
            except EOFError:
                print("Could not parse data dictionary (EOFError) - did the decryption fail?")
                sys.exit(601)
            if not isinstance(KeyData, dict):
                print("Malformed data!")
                sys.exit(666)
        else:
            KeyData = {}
    else:
        print("Unsupported command execution.")
        sys.exit(7)

    if cmd == "edit":
        tree = input("Please specify the card to edit/add/overwrite: ")
        dummy = {}
        dummy["PIV"] = {}
        dummy["Challenge"] = {}
        dummy["GPG"] = {}
        dummy["Serial"] = input("SERIAL: ")
        dummy["PIV"]["Management"] = input("PIV->Management: ")
        dummy["PIV"]["InitialPIN"] = input("PIV->InitialPIN: ")
        dummy["Challenge"]["Slot1"] = input("Challenge->Slot1: ")
        dummy["Challenge"]["Slot2"] = input("Challenge->Slot2: ")
        dummy["GPG"]["AdminPIN"] = input("GPG->AdminPIN: ")
        dummy["GPG"]["ResetCode"] = input("GPG->ResetCode: ")
        KeyData[tree] = dummy
    elif cmd == "known":
        print(f"The following keys are known: {KeyData.keys()}")
        sys.exit(0)
    elif cmd == "remove":
        tree = input("Please insert the card name to remove: ")
        del KeyData[tree]
    elif cmd == "show":
        try:
            print(dictString(KeyData[input("Which key do you want to display? ")], globalPrefix="-"))
        except KeyError:
            print("The specified key was not found. You can get the list of known keys with the \"known\" command.")
        sys.exit(0)

    if os.path.exists("Data"):
        os.remove("Data")
    if os.path.exists("Data.sig"):
        os.remove("Data.sig")

    gpgEncryption = subprocess.Popen(
        ["gpg", "--quiet", "--output", "Data", "--encrypt", "--recipient", "Markus@nerdgautica.net"],
        stdin=subprocess.PIPE,
        bufsize=0
    )
    pickle.dump(KeyData, gpgEncryption.stdin)
    gpgEncryption.stdin.close()
    os.system("gpg --detach-sign Data")