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