merkleeyes

A simple ABCI application serving a merkle-tree key-value store

Use

Merkleeyes allows inserts and removes by key, and queries by key or index. Inserts and removes happen through the DeliverTx message, while queries happen through the Query message. CheckTx simply mirrors DeliverTx.

Formatting

Byte arrays

Byte-array B is serialized to Encode(B) as follows:

Len(B) := Big-Endian encoded length of B
Encode(B) = Len(Len(B)) | Len(B) | B

So if B = "eric", then Encode(B) = 0x010465726963

Transactions

There are four types of transaction, each associated with a type-byte and a list of arguments:

Set			0x01		Key, Value
Remove			0x02		Key
Get			0x03		Key
Compare and Set		0x04		Key, Compare Value, Set Value
Validator Set Change    0x05		PubKey, Power (uint64)
Validator Set Read      0x06		
Validator Set CAS       0x07		Version (uint64), PubKey, Power (uint64)	

A transaction consists of a 12-byte random nonce, the type-byte, and the encoded arguments.

For instance, to insert a key-value pair, you would submit a transaction that looked like NONCE | 01 | Encode(key) | Encode(value), where | denotes concatenation. Thus, a transaction inserting the key-value pair (eric, clapton) would look like:

0xF4FCDC5BF26E227B66A1BA90010104657269630107636c6170746f6e

The first 12-bytes, F4FCDC5BF26E227B66A1BA90, are the nonce. The next byte, 01, is the transaction type. Following that are the encodings of eric and clapton.

Here's a session from the abci-cli:

# SET ("eric", "clapton")
> deliver_tx 0xF4FCDC5BF26E227B66A1BA90010104657269630107636c6170746f6e

# GET ("eric")
> deliver_tx 0xB980403FF73E79A3A2D90A1E03010465726963
-> data: clapton
-> data.hex: 636C6170746F6E

# CAS ("eric", "clapton", "ericson")
> deliver_tx 0x18D892B6D62773E6AA8804CF040104657269630107636C6170746F6E010765726963736f6e

# GET ("eric")
> deliver_tx 0x4FB9DAB513493E602FF085C603010465726963
-> data: ericson
-> data.hex: 65726963736F6E

# COMMIT
> commit
-> data: ���Ώ�R�Ng�=HK}��7�
-> data.hex: BAEDE5CE8F9A52B64E67873D484B7DABF69537DA

# QUERY ("eric")
> query 0x65726963
-> height: 2
-> key: eric
-> key.hex: 65726963
-> value: ericson
-> value.hex: 65726963736F6E

Poem

To the tune of Eric Clapton's "My Father's Eyes"

writing down, my checksum
waiting for the, data to come
no need to pray for integrity
thats cuz I use, a merkle tree

grab the root, with a quick hash run
if the hash works out,
it must have been done

theres no need, for trust to arise
thanks to the crypto
now that I can merkleyes

take that data, merklize
ye, I merklize ...

then the truth, begins to shine
the inverse of a hash, you will never find
and as I watch, the dataset grow
producing a proof, is never slow

Where do I find, the will to hash
How do I teach it?
It doesn't pay in cash
Bitcoin, here, I've realized
Thats what I need now,
cuz real currencies merklize
-EB