The idea is to "fortify" the asymmetric cryptography, and I'm calling it "Teikhos" from the Greek for "wall" or "fortification". It's built on one-time keys, where the next public-private key pair is hidden with the cipher 

`proof-of-public-key = f(nextPublicKey) xor sha512(nextPublicKey)`

When used as a standard signature on a public ledger, you just sign your transaction with the next key pair that you had uploaded a proof for, and if the public key from that signature solves the cipher, then the transaction gets authenticated. 

**Transaction format:**
```
transactionSignature // Asymmetric signature for the transaction, similar to in Ethereum 
                     // and Bitcoin, signed using the current public-private key pair

proof-of-public-key // Sets a new public-private key pair for the next transaction
```

<br>The Teikhos cipher protects the asymmetric cryptography from attacks except for the time-window between when a transaction has been broadcasted to the miners, to when it has been included in the state.

**The new bounty:** https://etherscan.io/address/0xfce151195f62ab55c117960216466f6d22dfa2a1#code

**Update:** smart contract for a new bounty with a commit/reveal scheme instead, https://gist.github.com/resilience-me/0b7a6c76a75a8540cdef49996771f3f5