Signature by some quorum member (validator) that told:

I agree to vote for block B with index I and hash H created by shard leaderL.The previous block hash was P

On a more technical level - the validator that is part of the current quorum when receiving a block proposal from the shard leader generates a signature:

import {crypto} from'web1337';let prevBlockHash ="b5d6a3736a146fe921e40be95b8e41a0f953a20aedb740769440be4b53795ff7";let blockID ="0:9GQ46rqY238rk2neSwgidap9ww5zbAN4dyqyC7j5ZnBK:1618";let blockHash ="36514c7acfd77950b23baced61f70bd7126f5dac4bc7f2eb110f364123901c42";// Epoch Full ID = epoch.hash+"#"+epoch.index// Just concat hash + # + indexlet epochFullID ="0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef#0";let dataThatShouldBeSigned = prevBlockHash+blockID+blockHash+epochFullID;// Imagine that validator holds it locallylet quorumValidatorPrivateKey ="MC4CAQAwBQYDK2VwBCIEILdhTMVYFz2GP8+uKUA+1FnZTEdN8eHFzbb8400cpEU9";let finalizationProof =awaitcrypto.ed25519.signEd25519(dataThatShouldBeSigned,quorumValidatorPrivateKey);

After quorum member generate this signature - it can be handled(by someone - since it proof is public) and aggregated to get the AFP - aggregated finalization proof

AFP - Aggregated Finalization Proof

Aggregation of 2/3N of FPs gives us AFP. This is how it looks like:

In our explorer you can check the AFP on the block page - look at the link next to the status

Clicking on the link will show you the raw version of AFP:

Probably the most interesting field here is proofs - these are just the FP's from the validators that are part of the quorum of the epoch when the block was generated.

You can verify it yourself using this code:

import {crypto} from'web1337';let prevBlockHash ="b5d6a3736a146fe921e40be95b8e41a0f953a20aedb740769440be4b53795ff7";let blockID ="0:9GQ46rqY238rk2neSwgidap9ww5zbAN4dyqyC7j5ZnBK:1618";let blockHash ="36514c7acfd77950b23baced61f70bd7126f5dac4bc7f2eb110f364123901c42";// Epoch Full ID = epoch.hash+"#"+epoch.index// Just concat hash + # + indexlet epochFullID ="0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef#0";let dataThatShouldBeSigned = prevBlockHash+blockID+blockHash+epochFullID;// Let verify FP for quorum member 9GQ46rqY238rk2neSwgidap9ww5zbAN4dyqyC7j5ZnBKlet quorumMember ="9GQ46rqY238rk2neSwgidap9ww5zbAN4dyqyC7j5ZnBK";let fpProof ="0pOSDm2Zr615gDociLowbGD3IU3eXZKqXOpGchHx8pQEBFThgKzRE2Qt+jTw4ikKJruVCMlDHjwaFOJuufJSAA==";let isFinalizationProofOk =awaitcrypto.ed25519.verifyEd25519(dataThatShouldBeSigned,fpProof, quorumMember);// In case 2/3N+1 of quorum created valid FPs - then this AFP is valid

LRP - Leader Rotation Proof

Signature by some quorum member (validator) that told:

I agree to finish FPs generation for shard leader L on index I and hash H. The hash of first block by this leader is F

ALRP - Aggregated Leader Rotation Proof

Aggregation of 2/3N of LRPs gives us ALRP. This is how it looks like:

Signature by some quorum member (validator) that told:

I agree to finish epoch X on shard Y. The last shard leader had index Q in leaders sequence. His last block has height W and hash H. His first block has hash F

AEFP - Aggregated Epoch Finalization Proof

Aggregation of 2/3N of EFPs gives us AEFP. This is how it looks like: