How One-shot Signatures Will Strengthen Cardano's Security

Cardano protects the immutability of the ledger, among other things, by using the Key-Evolving Signature (KES) scheme. The KES scheme provides so-called forward security. 

If the signing keys of SPOs are compromised, they cannot be exploited to overwrite the ledger history. This is because Cardano's protocol includes a mechanism where the keys used for signing blocks are rotated and the old keys are deleted. 

One of the security assumptions is that staking pool operators (SPOs) delete old keys. The One-shot Signatures (OSS) system will strengthen Cardano's security by making signing keys self-destruct after signing every new block. It will not be possible to sign the block again, as there will be no key to do so.

Forward security and KES Forward security is a property of cryptographic Read article: How One-shot Signatures Will Strengthen Cardano's Security