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package multisig
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import (
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"errors"
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"github.com/tendermint/tendermint/crypto"
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"github.com/tendermint/tendermint/crypto/multisig/bitarray"
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)
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// Multisignature is used to represent the signature object used in the multisigs.
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// Sigs is a list of signatures, sorted by corresponding index.
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type Multisignature struct {
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BitArray *bitarray.CompactBitArray
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Sigs [][]byte
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}
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// NewMultisig returns a new Multisignature of size n.
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func NewMultisig(n int) *Multisignature {
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// Default the signature list to have a capacity of two, since we can
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// expect that most multisigs will require multiple signers.
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return &Multisignature{bitarray.NewCompactBitArray(n), make([][]byte, 0, 2)}
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}
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// GetIndex returns the index of pk in keys. Returns -1 if not found
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func getIndex(pk crypto.PubKey, keys []crypto.PubKey) int {
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for i := 0; i < len(keys); i++ {
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if pk.Equals(keys[i]) {
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return i
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}
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}
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return -1
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}
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// AddSignature adds a signature to the multisig, at the corresponding index.
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// If the signature already exists, replace it.
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func (mSig *Multisignature) AddSignature(sig []byte, index int) {
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newSigIndex := mSig.BitArray.NumTrueBitsBefore(index)
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// Signature already exists, just replace the value there
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if mSig.BitArray.GetIndex(index) {
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mSig.Sigs[newSigIndex] = sig
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return
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}
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mSig.BitArray.SetIndex(index, true)
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// Optimization if the index is the greatest index
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if newSigIndex == len(mSig.Sigs) {
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mSig.Sigs = append(mSig.Sigs, sig)
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return
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}
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// Expand slice by one with a dummy element, move all elements after i
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// over by one, then place the new signature in that gap.
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mSig.Sigs = append(mSig.Sigs, make([]byte, 0))
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copy(mSig.Sigs[newSigIndex+1:], mSig.Sigs[newSigIndex:])
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mSig.Sigs[newSigIndex] = sig
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}
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// AddSignatureFromPubKey adds a signature to the multisig,
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// at the index in keys corresponding to the provided pubkey.
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func (mSig *Multisignature) AddSignatureFromPubKey(sig []byte, pubkey crypto.PubKey, keys []crypto.PubKey) error {
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index := getIndex(pubkey, keys)
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if index == -1 {
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return errors.New("provided key didn't exist in pubkeys")
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}
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mSig.AddSignature(sig, index)
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return nil
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}
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// Marshal the multisignature with amino
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func (mSig *Multisignature) Marshal() []byte {
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return cdc.MustMarshalBinaryBare(mSig)
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}
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