Refactor (Header, Last Commit) into Signed Header

[nashqueue]

Remove LastCommit from the Block as Current Commit will be saved.
Current Commit + Header is Signed Header.

Before:

message Block {	
	Header header = 1;
	Data data = 2;
	Commit last_commit = 3;
}

message SignedHeader {
	Header header = 1;
	Commit commit = 2;
}

message Commit {
	uint64 height = 1;
	bytes header_hash = 2;
	repeated bytes signatures = 3;
}

After:

message Block {	
	SignedHeader signedHeader = 1;
	Data data = 2;
}

message SignedHeader {
	Header header = 1;
	Commit commit = 2;
}

message Commit {
	uint64 height = 1;
	bytes header_hash = 2;
	repeated bytes signatures = 3;
}

[gupadhyaya]

@nashqueue

message Commit {
	uint64 height = 1;
	bytes header_hash = 2;
	repeated bytes signatures = 3;
}

why do we need to repeat height and header_hash in the Commit? these are already there in the SignedHeader.Header? may be we can just have:

message SignedHeader {
	Header header = 1;
	repeated bytes signatures = 2;
}

[nashqueue]

Agree

[gupadhyaya]

actually, we also need to add public_key to both header and signed header to be able to verify the signature. currently, we have proposer address from which we cannot get the public key.

type Header struct {
...
repeated bytes last_signatures = 3;
bytes last_public_key = 3;
...
}

message Commit {
	bytes signer_public_key = 1;
	repeated bytes signatures = 3;
}
message SignedHeader {
	Header header = 1;
	Commit commit = 2;
}

[nashqueue]

We already have

message Header {
...
	bytes proposer_address = 10;
...
}

So that should be enough for now to verify the signature.

[gupadhyaya]

i dont think so. i checked the code. proposer addr is only the first 20 bytes of the sha3 of public key. i dont think we can get the public key back using proposer addr. note that, we need public key for verifying the signature

[gupadhyaya]

@nashqueue there is also another issue. both Header and SignedHeader need to have the signer public keys. Otherwise, we won't be able to capture, if there is a change in the sequencer.

message Header {
     repeated bytes last_signer_keys = ...
     repeated bytes last_signatures = ...
}

and

message Commit {
     repeated bytes signer_keys = 1;
     repeated bytes signatures = 1;
}

message SignedHeader {
	Header header = 1;
	Commit commit = 2;
}