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SSZ: Add `bytesN`, remove `hashN` and `Address` (#455)

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Hsiao-Wei Wang 2019-01-17 19:02:57 +08:00 committed by Justin
parent 87fb35d244
commit 8d2f4a1705
1 changed files with 23 additions and 47 deletions
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specs/simple-serialize.md
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@ -15,20 +15,24 @@ deserializing objects and data types.
+ [Serialize/Encode](#serializeencode)
- [uint](#uint)
- [Bool](#bool)
- [Address](#address)
- [Hash](#hash)
- [Bytes](#bytes)
- [bytesN](#bytesn)
- [bytes](#bytes-1)
- [List/Vectors](#listvectors)
- [Container](#container)
+ [Deserialize/Decode](#deserializedecode)
- [uint](#uint-1)
- [Bool](#bool-1)
- [Address](#address-1)
- [Hash](#hash-1)
- [Bytes](#bytes-1)
- [Bytes](#bytes-2)
- [bytesN](#bytesn-1)
- [bytes](#bytes-1)
- [List/Vectors](#listvectors-1)
- [Container](#container-1)
+ [Tree Hash](#tree-hash)
- [`uint8`..`uint256`, `bool`, `bytes1`..`bytes32`](#uint8uint256-bool-bytes1bytes32)
- [`uint264`..`uintN`, `bytes`, `bytes33`..`bytesN`](#uint264uintn-bytes-bytes33bytesn)
- [List/Vectors](#listvectors-2)
- [Container](#container-2)
* [Implementations](#implementations)
## About
@ -58,7 +62,6 @@ overhead.
| `LENGTH_BYTES` | 4 | Number of bytes used for the length added before a variable-length serialized object. |
| `SSZ_CHUNK_SIZE` | 128 | Number of bytes for the chunk size of the Merkle tree leaf. |
## Overview
### Serialize/Encode
@ -97,32 +100,18 @@ assert(value in (True, False))
return b'\x01' if value is True else b'\x00'
```
#### Bytes
#### Address
The `address` should already come as a hash/byte format. Ensure that length is **20**.
| Check to perform | Code |
|:-----------------------|:---------------------|
| Length is correct (20) | ``len(value) == 20`` |
```python
assert( len(value) == 20 )
return value
```
#### Hash
| Hash Type | Usage |
|:---------:|:------------------------------------------------|
| `hashN` | Hash of arbitrary byte length `N`. |
| Bytes Type | Usage |
|:---------:|:------------------------------------|
| `bytesN` | Explicit length `N` bytes data. |
| `bytes` | Bytes data with arbitrary length. |
##### bytesN
| Checks to perform | Code |
|:---------------------------------------|:---------------------|
| Length in bytes is correct for `hashN` | ``len(value) == N`` |
##### hashN
| Length in bytes is correct for `bytesN` | ``len(value) == N`` |
```python
assert(len(value) == N)
@ -130,8 +119,7 @@ assert(len(value) == N)
return value
```
#### Bytes
##### bytes
For general `bytes` type:
1. Get the length/number of bytes; Encode into a `4-byte` integer.
2. Append the value to the length and return: ``[ length_bytes ] + [ value_bytes ]``
@ -263,19 +251,9 @@ assert rawbytes in (b'\x00', b'\x01')
return True if rawbytes == b'\x01' else False
```
#### Address
#### Bytes
Return the 20-byte deserialized address.
```python
assert(len(rawbytes) >= current_index + 20)
new_index = current_index + 20
return rawbytes[current_index:current_index+20], new_index
```
#### Hash
##### hashN
##### bytesN
Return the `N` bytes.
@ -285,7 +263,7 @@ new_index = current_index + N
return rawbytes[current_index:current_index+N], new_index
```
#### Bytes
##### bytes
Get the length of the bytes, return the bytes.
@ -394,11 +372,11 @@ The below `hash_tree_root` algorithm is defined recursively in the case of lists
Refer to [the helper function `hash`](https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#hash) of Phase 0 of the [Eth2.0 specs](https://github.com/ethereum/eth2.0-specs) for a definition of the hash function used below, `hash(x)`.
#### `uint8`..`uint256`, `bool`, `address`, `hash1`..`hash32`
#### `uint8`..`uint256`, `bool`, `bytes1`..`bytes32`
Return the serialization of the value.
#### `uint264`..`uintN`, `bytes`, `hash33`..`hashN`
#### `uint264`..`uintN`, `bytes`, `bytes33`..`bytesN`
Return the hash of the serialization of the value.
@ -443,7 +421,6 @@ return merkle_hash([hash_tree_root(item) for item in value])
Where the inner `hash_tree_root` is a recursive application of the tree-hashing function (returning less than 32 bytes for short single values).
#### Container
Recursively tree hash the values in the container in the same order as the fields, and return the hash of the concatenation of the results.
@ -452,12 +429,11 @@ Recursively tree hash the values in the container in the same order as the field
return hash(b''.join([hash_tree_root(getattr(x, field)) for field in value.fields]))
```
## Implementations
| Language | Implementation | Description |
|:--------:|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------|
| Python | [ https://github.com/ethereum/beacon_chain/blob/master/ssz/ssz.py ](https://github.com/ethereum/beacon_chain/blob/master/ssz/ssz.py) | Beacon chain reference implementation written in Python. |
| Python | [ https://github.com/ethereum/py-ssz ](https://github.com/ethereum/py-ssz) | Python implementation of SSZ |
| Rust | [ https://github.com/sigp/lighthouse/tree/master/beacon_chain/utils/ssz ](https://github.com/sigp/lighthouse/tree/master/beacon_chain/utils/ssz) | Lighthouse (Rust Ethereum 2.0 Node) maintained SSZ. |
| Nim | [ https://github.com/status-im/nim-beacon-chain/blob/master/beacon_chain/ssz.nim ](https://github.com/status-im/nim-beacon-chain/blob/master/beacon_chain/ssz.nim) | Nim Implementation maintained SSZ. |
| Rust | [ https://github.com/paritytech/shasper/tree/master/util/ssz ](https://github.com/paritytech/shasper/tree/master/util/ssz) | Shasper implementation of SSZ maintained by ParityTech. |