Data tokenization is simply the process of changing or substituting an important element or data with one that does not have any value. That one that does not have any value is referred to as a token.

I totally agree with you that everyone is sensitive about his or her sensitive information so that this information may not scale that's why there is a very simple process as you are talking about which change or substitute important data or sensitive data with another value which is meaningless and that meaningless values are tokens basically and if tokens are stolen by hackers then they can not steal personal information of someone without having corresponding information

Encryption requires a key to convert the illegible content to a readable form while tokenization uses a set of data which does not relate to the original data to substitute for it.

Above you are talking about encryption process which is another crucial process for the security of personal information and yes it in use a key when you have to make any transaction but if we talk about organisation then there is no need to use any key but the process of transaction proceeding in data tokenisation is something very different.

Overall I wish you good luck and success in this engagement challenge