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tree_hash -> SSZTreeHash

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vbuterin 2018-11-27 18:54:43 -05:00 committed by GitHub
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specs/simple-serialize.md
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@ -390,7 +390,7 @@ return typ(**values), item_index
### Tree Hash ### Tree Hash
The below `tree_hash` algorithm is defined recursively in the case of lists and containers, and it outputs a value equal to or less than 32 bytes in size. For the final output only (ie. not intermediate outputs), if the output is less than 32 bytes, right-zero-pad it to 32 bytes. The goal is collision resistance *within* each type, not between types. The below `SSZTreeHash` algorithm is defined recursively in the case of lists and containers, and it outputs a value equal to or less than 32 bytes in size. For the final output only (ie. not intermediate outputs), if the output is less than 32 bytes, right-zero-pad it to 32 bytes. The goal is collision resistance *within* each type, not between types.
We define `hash(x)` as `BLAKE2b-512(x)[0:32]`. We define `hash(x)` as `BLAKE2b-512(x)[0:32]`.
@ -435,13 +435,13 @@ def merkle_hash(lst):
return hash(chunkz[0] + datalen) return hash(chunkz[0] + datalen)
``` ```
To `tree_hash` a list, we simply do: To `SSZTreeHash` a list, we simply do:
```python ```python
return merkle_hash([tree_hash(item) for item in value]) return merkle_hash([SSZTreeHash(item) for item in value])
``` ```
Where the inner `tree_hash` is a recursive application of the tree-hashing function (returning less than 32 bytes for short single values). Where the inner `SSZTreeHash` is a recursive application of the tree-hashing function (returning less than 32 bytes for short single values).
#### Container #### Container
@ -449,7 +449,7 @@ Where the inner `tree_hash` is a recursive application of the tree-hashing funct
Recursively tree hash the values in the container in order sorted by key, and return the hash of the concatenation of the results. Recursively tree hash the values in the container in order sorted by key, and return the hash of the concatenation of the results.
```python ```python
return hash(b''.join([tree_hash(getattr(x, field)) for field in sorted(value.fields))) return hash(b''.join([SSZTreeHash(getattr(x, field)) for field in sorted(value.fields)))
``` ```