Skip to content
Permalink
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
66 lines (56 sloc) 2.33 KB
# beacon_chain
# Copyright (c) 2018-2019 Status Research & Development GmbH
# Licensed and distributed under either of
# * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
# * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.
# Serenity hash function / digest
#
# https://github.com/ethereum/eth2.0-specs/blob/v0.6.1/specs/core/0_beacon-chain.md#hash
#
# In Phase 0 the beacon chain is deployed with SHA256 (SHA2-256).
# Note that is is different from Keccak256 (often mistakenly called SHA3-256)
# and SHA3-256.
#
# In Eth1.0, the default hash function is Keccak256 and SHA256 is available as a precompiled contract.
#
# In our code base, to enable a smooth transition
# (already did Blake2b --> Keccak256 --> SHA2-256),
# we call this function `eth2hash`, and it outputs a `Eth2Digest`. Easy to sed :)
import
nimcrypto/[sha2, hash], eth/common/eth_types_json_serialization,
hashes
export
eth_types_json_serialization, hash.`$`
type
Eth2Digest* = MDigest[32 * 8] ## `hash32` from spec
Eth2Hash* = sha256 ## Context for hash function
func shortLog*(x: Eth2Digest): string =
# result = is needed to fix https://github.com/status-im/nim-beacon-chain/issues/209
result = ($x)[0..7]
# TODO: expose an in-place digest function
# when hashing in loop or into a buffer
# See: https://github.com/cheatfate/nimcrypto/blob/b90ba3abd/nimcrypto/sha2.nim#L570
func eth2hash*(v: openArray[byte]): Eth2Digest {.inline.} =
# We use the init-update-finish interface to avoid
# the expensive burning/clearing memory (20~30% perf)
# TODO: security implication?
var ctx: sha256
ctx.init()
ctx.update(v)
result = ctx.finish()
template withEth2Hash*(body: untyped): Eth2Digest =
## This little helper will init the hash function and return the sliced
## hash:
## let hashOfData = withHash: h.update(data)
var h {.inject.}: sha256
h.init()
body
var res = h.finish()
res
func hash*(x: Eth2Digest): Hash =
## Hash for digests for Nim hash tables
# Stub for BeaconChainDB
# We just slice the first 4 or 8 bytes of the block hash
# depending of if we are on a 32 or 64-bit platform
result = cast[ptr Hash](unsafeAddr x)[]
You can’t perform that action at this time.