128 lines
4.1 KiB
Nim
128 lines
4.1 KiB
Nim
# beacon_chain
|
|
# Copyright (c) 2018-2021 Status Research & Development GmbH
|
|
# Licensed and distributed under either of
|
|
# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
|
|
# * Apache v2 license (license terms in the root directory or at https://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/consensus-specs/blob/v1.1.0/specs/phase0/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 `eth2digest`, and it outputs a `Eth2Digest`. Easy to sed :)
|
|
|
|
{.push raises: [Defect].}
|
|
|
|
import
|
|
# Standard library
|
|
std/hashes,
|
|
# Status libraries
|
|
chronicles,
|
|
nimcrypto/[sha2, hash],
|
|
stew/[endians2, byteutils],
|
|
json_serialization,
|
|
blscurve
|
|
|
|
export
|
|
# Exports from sha2 / hash are explicit to avoid exporting upper-case `$` and
|
|
# constant-time `==`
|
|
sha2.update, hash.fromHex, json_serialization
|
|
|
|
type
|
|
Eth2Digest* = MDigest[32 * 8] ## `hash32` from spec
|
|
|
|
when BLS_BACKEND == BLST:
|
|
export blscurve.update
|
|
type Eth2DigestCtx* = BLST_SHA256_CTX
|
|
else:
|
|
type Eth2DigestCtx* = sha2.sha256
|
|
|
|
func `$`*(x: Eth2Digest): string =
|
|
x.data.toHex()
|
|
|
|
func shortLog*(x: Eth2Digest): string =
|
|
x.data.toOpenArray(0, 3).toHex()
|
|
|
|
chronicles.formatIt Eth2Digest:
|
|
shortLog(it)
|
|
|
|
# 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 eth2digest*(v: openArray[byte]): Eth2Digest {.noInit.} =
|
|
## Apply the Eth2 Hash function
|
|
## Do NOT use for secret data.
|
|
when BLS_BACKEND == BLST:
|
|
# BLST has a fast assembly optimized SHA256
|
|
result.data.bls_sha256_digest(v)
|
|
else:
|
|
# We use the init-update-finish interface to avoid
|
|
# the expensive burning/clearing memory (20~30% perf)
|
|
var ctx: Eth2DigestCtx
|
|
ctx.init()
|
|
ctx.update(v)
|
|
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)
|
|
when nimvm:
|
|
# In SSZ, computeZeroHashes require compile-time SHA256
|
|
block:
|
|
var h {.inject.}: sha256
|
|
init(h)
|
|
body
|
|
finish(h)
|
|
else:
|
|
when BLS_BACKEND == BLST:
|
|
block:
|
|
var h {.inject, noInit.}: Eth2DigestCtx
|
|
init(h)
|
|
body
|
|
var res {.noInit.}: Eth2Digest
|
|
finalize(res.data, h)
|
|
res
|
|
else:
|
|
block:
|
|
var h {.inject, noInit.}: Eth2DigestCtx
|
|
init(h)
|
|
body
|
|
finish(h)
|
|
|
|
template hash*(x: Eth2Digest): Hash =
|
|
## Hash for digests for Nim hash tables
|
|
# digests are already good hashes
|
|
cast[ptr Hash](unsafeAddr x.data[0])[]
|
|
|
|
func `==`*(a, b: Eth2Digest): bool =
|
|
when nimvm:
|
|
a.data == b.data
|
|
else:
|
|
# nimcrypto uses a constant-time comparison for all MDigest types which for
|
|
# Eth2Digest is unnecessary - the type should never hold a secret!
|
|
equalMem(unsafeAddr a.data[0], unsafeAddr b.data[0], sizeof(a.data))
|
|
|
|
proc writeValue*(w: var JsonWriter, a: Eth2Digest) {.raises: [Defect, IOError, SerializationError].} =
|
|
w.writeValue $a
|
|
|
|
proc readValue*(r: var JsonReader, a: var Eth2Digest) {.raises: [Defect, IOError, SerializationError].} =
|
|
try:
|
|
a = fromHex(type(a), r.readValue(string))
|
|
except ValueError:
|
|
raiseUnexpectedValue(r, "Hex string expected")
|
|
|
|
proc toGaugeValue*(hash: Eth2Digest): int64 =
|
|
# Only the last 8 bytes are taken into consideration in accordance
|
|
# to the ETH2 metrics spec:
|
|
# https://github.com/ethereum/eth2.0-metrics/blob/6a79914cb31f7d54858c7dd57eee75b6162ec737/metrics.md#interop-metrics
|
|
cast[int64](uint64.fromBytesLE(hash.data.toOpenArray(24, 31)))
|