61 lines
2.2 KiB
Nim
61 lines
2.2 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2019 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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# Serenity hash function / digest
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#
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# https://github.com/ethereum/eth2.0-specs/blob/v0.5.0/specs/core/0_beacon-chain.md#hash
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#
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# In Phase 0 the beacon chain is deployed with the same hash function as
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# Ethereum 1.0, i.e. Keccak-256 (also incorrectly known as SHA3).
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#
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# Note: We aim to migrate to a S[T/N]ARK-friendly hash function in a future
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# Ethereum 2.0 deployment phase.
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#
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# https://crypto.stackexchange.com/questions/15727/what-are-the-key-differences-between-the-draft-sha-3-standard-and-the-keccak-sub
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#
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# In our code base, to enable a smooth transition, we call this function
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# `eth2hash`, and it outputs a `Eth2Digest`. Easy to sed :)
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import
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nimcrypto/[keccak, hash], eth/common/eth_types_json_serialization,
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hashes
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export
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eth_types_json_serialization, hash.`$`
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type
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Eth2Digest* = MDigest[32 * 8] ## `hash32` from spec
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Eth2Hash* = keccak256 ## Context for hash function
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func shortLog*(x: Eth2Digest): string =
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# result = is needed to fix https://github.com/status-im/nim-beacon-chain/issues/209
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result = ($x)[0..7]
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func eth2hash*(v: openArray[byte]): Eth2Digest =
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var tmp = Eth2Hash.digest v
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copyMem(result.data.addr, tmp.addr, sizeof(result))
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template withEth2Hash*(body: untyped): Eth2Digest =
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## This little helper will init the hash function and return the sliced
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## hash:
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## let hashOfData = withHash: h.update(data)
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var h {.inject.}: Eth2Hash
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h.init()
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body
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var res: Eth2Digest
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var tmp = h.finish()
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copyMem(res.data.addr, tmp.data.addr, sizeof(res))
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res
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func hash*(x: Eth2Digest): Hash =
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## Hash for Keccak digests for Nim hash tables
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# Stub for BeaconChainDB
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# We just slice the first 4 or 8 bytes of the block hash
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# depending of if we are on a 32 or 64-bit platform
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result = cast[ptr Hash](unsafeAddr x)[]
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