Scaffold an initial cardano-crypto-leios package by ch1bo · Pull Request #670 · IntersectMBO/cardano-base

ch1bo · 2026-06-11T10:16:33Z

Adds a new package for leios cryptographic types and operations. This was done in course of IntersectMBO/ouroboros-consensus#2068, I'm currently integrating this with the cardano-ledger master and expect a follow-up PR there.

The digital signature scheme is BLS12-381 and fixed in the module. Contrary to the CIP-164, the certificate does not contain a slot or EbHash anymore. This makes definition in cardano-base a lot easier and in the current block structure design, the "message" against which the certificate is signed would be available from the (block) context in which the certificate is used.

Most importantly, this module contains encoders/decoders for the LeiosCert type including roundtrip and golden tests. This should be enough for the cardano-ledger to use this type confidently in Dijkstra era blocks.

There are also property tests about aggregating and verifying certificates. The Committee is part of this package, but how it is selected is deliberately kept out of scope.

Roundtrip and golden tests for LeiosCert

These are the only means to create and verify leios certificates about a certain message (a leios vote). Committee selection was deliberately kept out of scope

The golden test compares 'cardano-crypto-leios/test/golden/LeiosCert' byte-for-byte against the hex-dump output of 'encodeWithIndex'. Without this attribute, the default Windows 'core.autocrlf=true' translates LF to CRLF on checkout and the comparison fails, even though the file is committed with LF endings.

These were needed/useful in the cardano-ledger-dijkstra integration

This avoids redundant import warnings on newer GHC versions

lehins

Consistency is one of the most important parts in software development. It is important to use consistent dependencies as the rest of the project, in this case cardano-base repo being that project.

lehins · 2026-06-19T09:26:23Z

+-- skip per-key PoP checks (they use 'uncheckedAggregateVerKeysDSIGN' /
+-- 'aggregateSigsDSIGN' under the hood). Passing in unchecked keys defeats
+-- the security of the aggregate signature.
+newtype Committee = Committee {committeeVoters :: Vector (Weight, LeiosVerificationKey)}


Vector is lazy, which will easily lead to space leaks.
Having a lazy tuple as an element will exacerbate this issue.

At the very least I suggest creating a proper data type for the vector element, instead of using a tuple and be really diligent in forcing elements of a vector. Something like that:

Suggested change

newtype Committee = Committee {committeeVoters :: Vector (Weight, LeiosVerificationKey)}

newtype Committee = Committee {committeeVoters :: Vector LeiosVoter}

data LeiosVoter = LeiosVoter { leiosVoterWeight :: !Weight , leiosVoterVerKey :: !LeiosVerificationKey }

lehins · 2026-06-19T09:27:55Z

+  = -- | A voter index in the contributions is past the committee bound.
+    VoterIdOutOfBounds !VoterId
+  | -- | BLS signature aggregation failed (e.g. malformed input signature).
+    BLSAggregationFailed !String


List is lazy. Making it strict in WHNF is not very useful. Therefore it is best to switch to Text

Suggested change

BLSAggregationFailed !String

BLSAggregationFailed !Text

lehins · 2026-06-19T09:43:56Z

+
+-- | Plain CBOR decoder for 'LeiosCert', matching the CDDL in 'LeiosCert'.
+decodeLeiosCert :: Decoder s LeiosCert
+decodeLeiosCert = do


This decoder will be unusable in ledger, since it doesn't support indefinite length encoding

lehins · 2026-06-19T09:48:50Z

+aggregateLeiosCert committee contributions = do
+  let n = committeeSize committee
+      entries = Map.toAscList contributions
+  case [v | (v, _) <- entries, fromIntegral (voterIndex v) >= n] of


Creating a separate binding entries will cause that list to be allocated. However if we use Map directly in both places where it is used then we will tap into list fusion and avoid that list being allocated. Also we need to make sure all fromIntegral in this repo are type annotated

Suggested change

case [v | (v, _) <- entries, fromIntegral (voterIndex v) >= n] of

case [v | v <- Map.keys contributions, fromIntegral @Word32 @Int (voterIndex v) >= n] of

lehins · 2026-06-19T09:49:11Z

+    v : _ -> Left (VoterIdOutOfBounds v)
+    [] -> pure ()
+  aggSig <-
+    case aggregateSigsDSIGN (map snd entries) of


Suggested change

case aggregateSigsDSIGN (map snd entries) of

case aggregateSigsDSIGN (Map.elems contributions) of

lehins · 2026-06-19T09:51:44Z

+  { signers :: !BitField
+  , aggregatedSignature :: !LeiosSignature


This is a pretty terrible naming, since signers can easily be a local binding anywhere in the cardano-node codebase. I suggest something more descriptive like:

Suggested change

{ signers :: !BitField

, aggregatedSignature :: !LeiosSignature

{ leisCertSigners :: !BitField

, leisCertSignature :: !LeiosSignature

-- ^ Aggregated BLS signature

lehins · 2026-06-19T09:54:51Z

+  where
+    -- The bitfield decoder already enforced @i < n@; if the committee is
+    -- shorter than the decoder's idea of @n@ we treat it as a malformed cert.
+    accumSigner voters (w, ks) i = case voters V.!? i of


We should avoid space leaks as much as we can!

Suggested change

accumSigner voters (w, ks) i = case voters V.!? i of

accumSigner voters (!w, !ks) i = case voters V.!? i of

ch1bo mentioned this pull request Jun 11, 2026

Prototype certificate aggregation and validation IntersectMBO/ouroboros-consensus#2068

Open

2 tasks

ch1bo changed the title ~~WIP: Scaffold an initial cardano-crypto-leios package~~ Scaffold an initial cardano-crypto-leios package Jun 11, 2026

ch1bo force-pushed the ch1bo/cardano-crypto-leios branch from d85df0c to aa227fa Compare June 16, 2026 14:56

ch1bo requested review from lehins and perturbing June 16, 2026 18:10

ch1bo marked this pull request as ready for review June 16, 2026 18:10

ch1bo force-pushed the ch1bo/cardano-crypto-leios branch from bf92c7d to 780e347 Compare June 17, 2026 07:22

ch1bo mentioned this pull request Jun 17, 2026

Add LeiosCert to DijkstraBlockBody IntersectMBO/cardano-ledger#5872

Open

10 tasks

ch1bo force-pushed the ch1bo/cardano-crypto-leios branch 2 times, most recently from 1102098 to 25e16ac Compare June 17, 2026 21:21

ch1bo added 12 commits June 18, 2026 11:38

Scaffold an initial cardano-crypto-leios package

375d24d

Not include slot/eb hash in leios certificate

5a53f50

Add cardano-crypto-leios test suite

0fdc1f6

Roundtrip and golden tests for LeiosCert

Add functions to aggregateLeiosCert and verifyLeiosCert

b649389

These are the only means to create and verify leios certificates about a certain message (a leios vote). Committee selection was deliberately kept out of scope

Add more properties and range over commitee size

ceb3206

Refactor BitField in LeiosCert

6b83b6a

Drop explicit export list

c41a7a2

Avoid head and name shadowing in tests

1172911

Expose generators in cardano-crypto-leios:testlib

26a0d01

Add genLeiosSignature, leiosSignatureSize and leiosSignatureToBytes

a1f778d

These were needed/useful in the cardano-ledger-dijkstra integration

Add a generateWith helper

d1d5fd2

ch1bo force-pushed the ch1bo/cardano-crypto-leios branch 2 times, most recently from 73d303e to 745de18 Compare June 18, 2026 19:18

Use qualified import of foldl' from Data.Foldable

38a3b98

This avoids redundant import warnings on newer GHC versions

ch1bo force-pushed the ch1bo/cardano-crypto-leios branch from 745de18 to 38a3b98 Compare June 18, 2026 19:24

lehins requested changes Jun 19, 2026

View reviewed changes

Switch cardano-crypto-leios tests to quickcheck

a52fe70

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Scaffold an initial cardano-crypto-leios package#670

Scaffold an initial cardano-crypto-leios package#670
ch1bo wants to merge 14 commits into
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ch1bo commented Jun 11, 2026 •

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	newtype Committee = Committee {committeeVoters :: Vector (Weight, LeiosVerificationKey)}
	newtype Committee = Committee {committeeVoters :: Vector LeiosVoter}

	case [v \| (v, _) <- entries, fromIntegral (voterIndex v) >= n] of
	case [v \| v <- Map.keys contributions, fromIntegral @Word32 @Int (voterIndex v) >= n] of

	case aggregateSigsDSIGN (map snd entries) of
	case aggregateSigsDSIGN (Map.elems contributions) of

		{ signers :: !BitField
		, aggregatedSignature :: !LeiosSignature

-  { signers :: !BitField
-  , aggregatedSignature :: !LeiosSignature
+  { leisCertSigners :: !BitField
+  , leisCertSignature :: !LeiosSignature
+  -- ^ Aggregated BLS signature

	accumSigner voters (w, ks) i = case voters V.!? i of
	accumSigner voters (!w, !ks) i = case voters V.!? i of

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ch1bo commented Jun 11, 2026 •

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