LSAG

Implementation of Linkable Spontaneus Anonymous Group (LSAG) Signature over elliptic curve cryptography.

>>> (pubKey, privKey) <- ECC.generate curve -- Generate public and private keys
>>> extPubKeys <- genNPubKeys curve nParticipants -- Generate random foreign participants
>>> k <- fromInteger <$> generateBetween 0 (toInteger $ length extPubKeys - 1) -- Position of the signer's key in the public keys list (k)
>>> let pubKeys = insert k pubKey extPubKeys -- Insert signer's public key into the list of public keys
>>> signature <- sign pubKeys (pubKey, privKey) msg -- Sign message with list of public keys and signer's key pair
>>> verify pubKeys signature msg -- Verify signature
True

Documentation

sign

Arguments

:: (MonadRandom m, MonadFail m)

=> [PublicKey]

List of public keys

-> (PublicKey, PrivateKey)

Signer's public and private keys

-> ByteString

Message

-> m (Integer, [Integer], Point)

Generates a ring signature for a message given a specific set of public keys and a signing key belonging to one of the public keys in the set

It returns a signature (c0, ss, y) :

• c0: Initial value to reconstruct signature.
• ss: vector of randomly generated values with encrypted secret to reconstruct signature {s0 ... sn-1}.
• y: Link for current signer.

verify

Arguments

:: [PublicKey]

List of participants public keys

-> (Integer, [Integer], Point)

Signature

-> ByteString

Message

-> Bool

Verify if a valid signature was made by any public key in the set of public keys L.

Return a boolean value indicating if signature is valid.

genNPubKeys :: MonadRandom m => Curve -> Int -> m [PublicKey]

Generate N different public keys. L = {y1, ..., yn}