👉 Invalidation is a process in computer science and information theory where a document or message can be altered by removing or replacing parts of it. This process is commonly used in digital signatures, which are cryptographic methods that allow for secure communication between two parties over an encrypted channel. In the context of invalidation, this means that the original document or message cannot be recovered from its modified form once it has been altered, as it would have no physical copies to compare against. This can lead to significant security vulnerabilities