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randombeacon_inspector.go
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randombeacon_inspector.go
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package hotstuff
import (
"github.com/onflow/crypto"
)
// RandomBeaconInspector encapsulates all methods needed by a Hotstuff leader to validate the
// beacon votes and reconstruct a beacon signature.
// The random beacon methods are based on a threshold signature scheme.
type RandomBeaconInspector interface {
// Verify verifies the signature share under the signer's public key and the message agreed upon.
// The function is thread-safe and wait-free (i.e. allowing arbitrary many routines to
// execute the business logic, without interfering with each other).
// It allows concurrent verification of the given signature.
// Returns :
// - model.InvalidSignerError if signerIndex is invalid
// - model.ErrInvalidSignature if signerIndex is valid but signature is cryptographically invalid
// - other error if there is an unexpected exception.
Verify(signerIndex int, share crypto.Signature) error
// TrustedAdd adds a share to the internal signature shares store.
// There is no pre-check of the signature's validity _before_ adding it.
// It is the caller's responsibility to make sure the signature was previously verified.
// Nevertheless, the implementation guarantees safety (only correct threshold signatures
// are returned) through a post-check (verifying the threshold signature
// _after_ reconstruction before returning it).
// The function is thread-safe but locks its internal state, thereby permitting only
// one routine at a time to add a signature.
// Returns:
// - (true, nil) if the signature has been added, and enough shares have been collected.
// - (false, nil) if the signature has been added, but not enough shares were collected.
// - (false, error) if there is any exception adding the signature share.
// - model.InvalidSignerError if signerIndex is invalid (out of the valid range)
// - model.DuplicatedSignerError if the signer has been already added
// - other error if there is an unexpected exception.
TrustedAdd(signerIndex int, share crypto.Signature) (enoughshares bool, exception error)
// EnoughShares indicates whether enough shares have been accumulated in order to reconstruct
// a group signature. The function is thread-safe.
EnoughShares() bool
// Reconstruct reconstructs the group signature. The function is thread-safe but locks
// its internal state, thereby permitting only one routine at a time.
//
// Returns:
// - (signature, nil) if no error occurred
// - (nil, model.InsufficientSignaturesError) if not enough shares were collected
// - (nil, model.InvalidSignatureIncluded) if at least one collected share does not serialize to a valid BLS signature,
// or if the constructed signature failed to verify against the group public key and stored message. This post-verification
// is required for safety, as `TrustedAdd` allows adding invalid signatures.
// - (nil, error) for any other unexpected error.
Reconstruct() (crypto.Signature, error)
}