2018-11-28 19:49:03 +00:00
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# beacon_chain
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2019-02-28 21:24:43 +00:00
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# Copyright (c) 2018-2019 Status Research & Development GmbH
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2018-11-28 19:49:03 +00:00
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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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# At the time of writing, the exact definitions of what should be used for
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# cryptography in the spec is in flux, with sizes and test vectors still being
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# hashed out. This layer helps isolate those chagnes.
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2018-12-27 20:14:37 +00:00
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# Useful conversation about BLS signatures (TODO: condense this)
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#
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# I can probably google this somehow, but bls signatures, anyone knows off the
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# top of their head if they have to be combined one by one, or can two group
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# signatures be combined? what happens to overlap then?
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# Danny Ryan
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# @djrtwo
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# Dec 21 12:00
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# Yeah, you can do any linear combination of signatures. but you have to
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# remember the linear combination of pubkeys that constructed
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# if you have two instances of a signature from pubkey p, then you need 2*p in
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# the group pubkey
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# because the attestation bitfield is only 1 bit per pubkey right now,
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# attestations do not support this
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# it could be extended to support N overlaps up to N times per pubkey if we
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# had N bits per validator instead of 1
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# We are shying away from this for the time being. If there end up being
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# substantial difficulties in network layer aggregation, then adding bits
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# to aid in supporting overlaps is one potential solution
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# Jacek Sieka
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# @arnetheduck
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# Dec 21 12:02
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# ah nice, you anticipated my followup question there :) so it's not a
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# straight-off set union operation
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# Danny Ryan
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# @djrtwo
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# Dec 21 12:02
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# depending on the particular network level troubles we run into
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# right
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# aggregatng sigs and pubkeys are both just ec adds
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# https://github.com/ethereum/py-evm/blob/d82b10ae361cde6abbac62f171fcea7809c4e3cf/eth/_utils/bls.py#L191-L202
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# subtractions work too (i suppose this is obvious). You can linearly combine
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# sigs or pubs in any way
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2018-11-28 19:49:03 +00:00
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import
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2019-02-28 21:24:43 +00:00
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sequtils,
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2019-07-03 07:35:05 +00:00
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stew/objects, hashes, eth/rlp, nimcrypto/utils,
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2019-03-25 16:46:31 +00:00
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blscurve, json_serialization,
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digest
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2018-12-19 12:58:53 +00:00
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export
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2019-03-01 13:34:37 +00:00
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json_serialization
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2019-02-05 16:13:29 +00:00
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2019-02-07 10:51:21 +00:00
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export blscurve.init, blscurve.getBytes, blscurve.combine, blscurve.`$`, blscurve.`==`
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2018-11-28 19:49:03 +00:00
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type
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2019-07-03 07:35:05 +00:00
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BlsValueType* = enum
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Real
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OpaqueBlob
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BlsValue*[T] = object
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# TODO This is a temporary type needed until we sort out the
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# issues with invalid BLS values appearing in the SSZ test suites.
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case kind*: BlsValueType
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of Real:
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blsValue*: T
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of OpaqueBlob:
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when T is blscurve.Signature:
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blob*: array[96, byte]
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else:
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blob*: array[48, byte]
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ValidatorPubKey* = BlsValue[blscurve.VerKey]
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# ValidatorPubKey* = blscurve.VerKey
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# ValidatorPubKey* = array[48, byte]
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# The use of byte arrays proved to be a dead end pretty quickly.
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# Plenty of code needs to be modified for a successful build and
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# the changes will negatively affect the performance.
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# ValidatorPrivKey* = BlsValue[blscurve.SigKey]
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2019-02-05 16:13:29 +00:00
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ValidatorPrivKey* = blscurve.SigKey
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2019-07-03 07:35:05 +00:00
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ValidatorSig* = BlsValue[blscurve.Signature]
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BlsCurveType* = VerKey|SigKey|Signature
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2019-02-05 16:13:29 +00:00
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ValidatorPKI* = ValidatorPrivKey|ValidatorPubKey|ValidatorSig
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2018-11-29 01:08:34 +00:00
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2019-07-03 07:35:05 +00:00
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proc init*[T](BLS: type BlsValue[T], val: auto): BLS =
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result.kind = BlsValueType.Real
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result.blsValue = init(T, val)
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func `$`*(x: BlsValue): string =
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if x.kind == Real:
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$x.blsValue
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else:
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2019-08-05 00:00:49 +00:00
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# r: is short for random. The prefix must be short
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# due to the mechanics of the `shortLog` function.
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2019-07-03 07:35:05 +00:00
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"r:" & toHex(x.blob)
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func `==`*(a, b: BlsValue): bool =
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if a.kind != b.kind: return false
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if a.kind == Real:
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return a.blsValue == b.blsValue
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else:
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return a.blob == b.blob
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func getBytes*(x: BlsValue): auto =
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if x.kind == Real:
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getBytes x.blsValue
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else:
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x.blob
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func shortLog*(x: BlsValue): string =
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($x)[0..7]
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func shortLog*(x: BlsCurveType): string =
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2019-02-28 21:21:29 +00:00
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($x)[0..7]
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2019-07-03 07:35:05 +00:00
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proc hash*(x: BlsValue): Hash {.inline.} =
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if x.kind == Real:
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hash x.blsValue.getBytes()
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else:
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hash x.blob
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template hash*(x: BlsCurveType): Hash =
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hash(getBytes(x))
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template `==`*[T](a: BlsValue[T], b: T): bool =
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a.blsValue == b
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template `==`*[T](a: T, b: BlsValue[T]): bool =
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a == b.blsValue
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func pubKey*(pk: ValidatorPrivKey): ValidatorPubKey =
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when ValidatorPubKey is BlsValue:
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ValidatorPubKey(kind: Real, blsValue: pk.getKey())
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elif ValidatorPubKey is array:
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pk.getKey.getBytes
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else:
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pk.getKey
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proc combine*[T](a: openarray[BlsValue[T]]): T =
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doAssert a.len > 0 and a[0].kind == Real
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result = a[0].blsValue
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for i in 1 ..< a.len:
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doAssert a[i].kind == Real
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result.combine a[i].blsValue
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2018-11-29 01:08:34 +00:00
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2019-07-03 07:35:05 +00:00
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proc combine*[T](x: var BlsValue[T], other: BlsValue[T]) =
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doAssert x.kind == Real and other.kind == Real
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x.blsValue.combine(other.blsValue)
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2018-12-05 13:58:41 +00:00
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2019-07-03 07:35:05 +00:00
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# https://github.com/ethereum/eth2.0-specs/blob/v0.8.1/specs/bls_signature.md#bls_aggregate_pubkeys
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2018-12-17 19:36:17 +00:00
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func bls_aggregate_pubkeys*(keys: openArray[ValidatorPubKey]): ValidatorPubKey =
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2018-12-21 23:47:55 +00:00
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var empty = true
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2018-12-11 17:55:45 +00:00
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for key in keys:
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if empty:
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result = key
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empty = false
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else:
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result.combine(key)
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2019-07-03 07:35:05 +00:00
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# https://github.com/ethereum/eth2.0-specs/blob/v0.8.1/specs/bls_signature.md#bls_verify
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2018-12-17 19:36:17 +00:00
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func bls_verify*(
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2018-12-11 17:55:45 +00:00
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pubkey: ValidatorPubKey, msg: openArray[byte], sig: ValidatorSig,
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domain: uint64): bool =
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# name from spec!
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2019-07-03 07:35:05 +00:00
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when ValidatorPubKey is BlsValue:
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doAssert sig.kind == Real and pubkey.kind == Real
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sig.blsValue.verify(msg, domain, pubkey.blsValue)
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else:
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sig.verify(msg, domain, pubkey)
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2019-02-05 16:13:29 +00:00
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2019-07-03 07:35:05 +00:00
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# https://github.com/ethereum/eth2.0-specs/blob/v0.8.1/specs/bls_signature.md#bls_verify_multiple
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2019-02-07 23:07:15 +00:00
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func bls_verify_multiple*(
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2019-03-25 16:46:31 +00:00
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pubkeys: seq[ValidatorPubKey], message_hashes: openArray[Eth2Digest],
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2019-02-07 23:07:15 +00:00
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sig: ValidatorSig, domain: uint64): bool =
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let L = len(pubkeys)
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2019-02-28 21:24:43 +00:00
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doAssert L == len(message_hashes)
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2019-08-05 00:00:49 +00:00
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doAssert sig.kind == Real
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2019-02-28 21:24:43 +00:00
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# TODO optimize using multiPairing
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for pubkey_message_hash in zip(pubkeys, message_hashes):
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let (pubkey, message_hash) = pubkey_message_hash
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2019-08-05 00:00:49 +00:00
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doAssert pubkey.kind == Real
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2019-02-28 21:24:43 +00:00
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# TODO spec doesn't say to handle this specially, but it's silly to
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# validate without any actual public keys.
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2019-08-05 00:00:49 +00:00
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if pubkey.blsValue != VerKey() and
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not sig.blsValue.verify(message_hash.data, domain, pubkey.blsValue):
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2019-02-28 21:24:43 +00:00
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return false
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2019-02-07 23:07:15 +00:00
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true
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2019-07-03 07:35:05 +00:00
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when ValidatorPrivKey is BlsValue:
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func bls_sign*(key: ValidatorPrivKey, msg: openarray[byte],
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domain: uint64): ValidatorSig =
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# name from spec!
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if key.kind == Real:
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ValidatorSig(kind: Real, blsValue: key.blsValue.sign(domain, msg))
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else:
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ValidatorSig(kind: OpaqueBlob)
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else:
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func bls_sign*(key: ValidatorPrivKey, msg: openarray[byte],
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domain: uint64): ValidatorSig =
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# name from spec!
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ValidatorSig(kind: Real, blsValue: key.sign(domain, msg))
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proc fromBytes*[T](R: type BlsValue[T], bytes: openarray[byte]): R =
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when defined(ssz_testing):
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result = R(kind: OpaqueBlob, blob: toArray(result.blob.len, bytes))
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else:
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result = R(kind: Real, blsValue: init(T, bytes))
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proc initFromBytes*[T](val: var BlsValue[T], bytes: openarray[byte]) =
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val = fromBytes(BlsValue[T], bytes)
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proc initFromBytes*(val: var BlsCurveType, bytes: openarray[byte]) =
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val = init(type(val), bytes)
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2018-12-19 12:58:53 +00:00
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proc writeValue*(writer: var JsonWriter, value: ValidatorPubKey) {.inline.} =
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2019-07-03 07:35:05 +00:00
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when value is BlsValue:
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doAssert value.kind == Real
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writer.writeValue($value.blsValue)
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else:
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writer.writeValue($value)
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2018-12-19 12:58:53 +00:00
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proc readValue*(reader: var JsonReader, value: var ValidatorPubKey) {.inline.} =
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2019-07-03 07:35:05 +00:00
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value.initFromBytes(fromHex reader.readValue(string))
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2018-12-19 12:58:53 +00:00
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proc writeValue*(writer: var JsonWriter, value: ValidatorSig) {.inline.} =
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2019-07-03 07:35:05 +00:00
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when value is BlsValue:
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doAssert value.kind == Real
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writer.writeValue($value.blsValue)
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else:
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writer.writeValue($value)
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2018-12-19 12:58:53 +00:00
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proc readValue*(reader: var JsonReader, value: var ValidatorSig) {.inline.} =
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2019-07-03 07:35:05 +00:00
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value.initFromBytes(fromHex reader.readValue(string))
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2018-12-19 12:58:53 +00:00
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proc writeValue*(writer: var JsonWriter, value: ValidatorPrivKey) {.inline.} =
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2019-07-03 07:35:05 +00:00
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when value is BlsValue:
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doAssert value.kind == Real
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writer.writeValue($value.blsValue)
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else:
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writer.writeValue($value)
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2018-12-19 12:58:53 +00:00
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proc readValue*(reader: var JsonReader, value: var ValidatorPrivKey) {.inline.} =
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2019-07-03 07:35:05 +00:00
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value.initFromBytes(fromHex reader.readValue(string))
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2018-12-19 12:58:53 +00:00
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2019-07-03 07:35:05 +00:00
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when ValidatorPrivKey is BlsValue:
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proc newPrivKey*(): ValidatorPrivKey =
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ValidatorPrivKey(kind: Real, blsValue: SigKey.random())
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else:
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proc newPrivKey*(): ValidatorPrivKey =
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SigKey.random()
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2019-03-01 16:51:37 +00:00
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2019-02-18 10:34:39 +00:00
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# RLP serialization (TODO: remove if no longer necessary)
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2019-07-03 07:35:05 +00:00
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when ValidatorPubKey is BlsValue:
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proc append*(writer: var RlpWriter, value: ValidatorPubKey) =
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writer.append if value.kind == Real: value.blsValue.getBytes()
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else: value.blob
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else:
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proc append*(writer: var RlpWriter, value: ValidatorPubKey) =
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writer.append value.getBytes()
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2019-03-01 16:51:37 +00:00
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proc read*(rlp: var Rlp, T: type ValidatorPubKey): T {.inline.} =
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2019-07-03 07:35:05 +00:00
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result fromBytes(T, rlp.toBytes)
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2019-03-01 16:51:37 +00:00
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2019-07-03 07:35:05 +00:00
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when ValidatorSig is BlsValue:
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proc append*(writer: var RlpWriter, value: ValidatorSig) =
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writer.append if value.kind == Real: value.blsValue.getBytes()
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else: value.blob
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else:
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proc append*(writer: var RlpWriter, value: ValidatorSig) =
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writer.append value.getBytes()
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2019-03-01 16:51:37 +00:00
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proc read*(rlp: var Rlp, T: type ValidatorSig): T {.inline.} =
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2019-07-03 07:35:05 +00:00
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let bytes = fromBytes(T, rlp.toBytes)
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2019-03-01 16:51:37 +00:00
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