44 lines
1.7 KiB
Nim
44 lines
1.7 KiB
Nim
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# beacon_chain
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# Copyright (c) 2018 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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# From spec:
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#
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# We aim to have a STARK-friendly hash function `hash(x)` for the production
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# launch of the beacon chain. While the standardisation process for a
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# STARK-friendly hash function takes place—led by STARKware, who will produce a
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# detailed report with recommendations—we use `BLAKE2b-512` as a placeholder.
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# Specifically, we set `hash(x) := BLAKE2b-512(x)[0:32]` where the `BLAKE2b-512`
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# algorithm is defined in [RFC 7693](https://tools.ietf.org/html/rfc7693) and
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# the input `x` is of type `bytes`.
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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 nimcrypto/[blake2, hash]
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type
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Eth2Digest* = MDigest[32 * 8] ## `hash32` from spec
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Eth2Hash* = blake2_512 ## Context for hash function
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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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