What is the reason for using a double key system for tokens?

A dual key system for tokens (e.g., access key and secret key) is used to enhance security and facilitate access management.

Main reasons:

• Role separation: One key (e.g., public access key) is used for client identification, while the other (secret key) is used for authentication and signing requests.
• Security: The secret key is not transmitted in plain text and is stored only on the client side, reducing the risk of compromise.
• Access management: It is possible to revoke or replace one of the keys without a complete system failure.
• Request signing: The secret key is used to create a digital signature, which is verified by the server, ensuring data integrity and authenticity.

For example, AWS uses Access Key ID and Secret Access Key: the first is a public identifier, and the second is secret, used for signing requests.