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package multisig
import (
"github.com/tendermint/tendermint/crypto"
"github.com/tendermint/tendermint/crypto/tmhash"
)
// ThresholdMultiSignaturePubKey implements a K of N threshold multisig.
type ThresholdMultiSignaturePubKey struct {
K uint `json:"threshold"`
Pubkeys []crypto.PubKey `json:"pubkeys"`
}
var _ crypto.PubKey = &ThresholdMultiSignaturePubKey{}
// NewThresholdMultiSignaturePubKey returns a new ThresholdMultiSignaturePubKey.
// Panics if len(pubkeys) < k or 0 >= k.
func NewThresholdMultiSignaturePubKey(k int, pubkeys []crypto.PubKey) crypto.PubKey {
if k <= 0 {
panic("threshold k of n multisignature: k <= 0")
}
if len(pubkeys) < k {
panic("threshold k of n multisignature: len(pubkeys) < k")
}
return &ThresholdMultiSignaturePubKey{uint(k), pubkeys}
}
// VerifyBytes expects sig to be an amino encoded version of a MultiSignature.
// Returns true iff the multisignature contains k or more signatures
// for the correct corresponding keys,
// and all signatures are valid. (Not just k of the signatures)
// The multisig uses a bitarray, so multiple signatures for the same key is not
// a concern.
func (pk *ThresholdMultiSignaturePubKey) VerifyBytes(msg []byte, marshalledSig []byte) bool {
var sig *Multisignature
err := cdc.UnmarshalBinaryBare(marshalledSig, &sig)
if err != nil {
return false
}
size := sig.BitArray.Size()
// ensure bit array is the correct size
if len(pk.Pubkeys) != size {
return false
}
// ensure size of signature list
if len(sig.Sigs) < int(pk.K) || len(sig.Sigs) > size {
return false
}
// ensure at least k signatures are set
if sig.BitArray.NumTrueBitsBefore(size) < int(pk.K) {
return false
}
// index in the list of signatures which we are concerned with.
sigIndex := 0
for i := 0; i < size; i++ {
if sig.BitArray.GetIndex(i) {
if !pk.Pubkeys[i].VerifyBytes(msg, sig.Sigs[sigIndex]) {
return false
}
sigIndex++
}
}
return true
}
// Bytes returns the amino encoded version of the ThresholdMultiSignaturePubKey
func (pk *ThresholdMultiSignaturePubKey) Bytes() []byte {
return cdc.MustMarshalBinaryBare(pk)
}
// Address returns tmhash(ThresholdMultiSignaturePubKey.Bytes())
func (pk *ThresholdMultiSignaturePubKey) Address() crypto.Address {
return crypto.Address(tmhash.Sum(pk.Bytes()))
}
// Equals returns true iff pk and other both have the same number of keys, and
// all constituent keys are the same, and in the same order.
func (pk *ThresholdMultiSignaturePubKey) Equals(other crypto.PubKey) bool {
otherKey, sameType := other.(*ThresholdMultiSignaturePubKey)
if !sameType {
return false
}
if pk.K != otherKey.K || len(pk.Pubkeys) != len(otherKey.Pubkeys) {
return false
}
for i := 0; i < len(pk.Pubkeys); i++ {
if !pk.Pubkeys[i].Equals(otherKey.Pubkeys[i]) {
return false
}
}
return true
}