path: root/core/crypto.go

// Copyright 2018 The dexon-consensus-core Authors
// This file is part of the dexon-consensus-core library.
//
// The dexon-consensus-core library is free software: you can redistribute it
// and/or modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The dexon-consensus-core library is distributed in the hope that it will be
// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the dexon-consensus-core library. If not, see
// <http://www.gnu.org/licenses/>.

package core

import (
    "encoding/binary"
    "sort"

    "github.com/dexon-foundation/dexon-consensus-core/common"
    "github.com/dexon-foundation/dexon-consensus-core/core/types"
    "github.com/dexon-foundation/dexon-consensus-core/crypto"
)

func hashNotary(block *types.Block) (common.Hash, error) {
    binaryTime, err := block.Notary.Timestamp.MarshalBinary()
    if err != nil {
        return common.Hash{}, err
    }
    binaryHeight := make([]byte, 8)
    binary.LittleEndian.PutUint64(binaryHeight, block.Notary.Height)
    hash := crypto.Keccak256Hash(
        block.Notary.ParentHash[:],
        binaryTime,
        binaryHeight)
    return hash, nil
}

func verifyNotarySignature(pubkey crypto.PublicKey,
    notaryBlock *types.Block, sig crypto.Signature) (bool, error) {
    hash, err := hashNotary(notaryBlock)
    if err != nil {
        return false, err
    }
    return pubkey.VerifySignature(hash, sig), nil
}

func hashBlock(block *types.Block) (common.Hash, error) {
    hashPosition := hashPosition(block.Position)
    // Handling Block.Acks.
    acks := make(common.Hashes, 0, len(block.Acks))
    for ack := range block.Acks {
        acks = append(acks, ack)
    }
    sort.Sort(acks)
    binaryAcks := make([][]byte, len(block.Acks))
    for idx := range acks {
        binaryAcks[idx] = acks[idx][:]
    }
    hashAcks := crypto.Keccak256Hash(binaryAcks...)
    // Handle Block.Timestamps.
    // TODO(jimmy-dexon): Store and get the sorted validatorIDs.
    validators := make(types.ValidatorIDs, 0, len(block.Timestamps))
    for vID := range block.Timestamps {
        validators = append(validators, vID)
    }
    sort.Sort(validators)
    binaryTimestamps := make([][]byte, len(block.Timestamps))
    for idx, vID := range validators {
        var err error
        binaryTimestamps[idx], err = block.Timestamps[vID].MarshalBinary()
        if err != nil {
            return common.Hash{}, err
        }
    }
    hashTimestamps := crypto.Keccak256Hash(binaryTimestamps...)
    payloadHash := crypto.Keccak256Hash(block.Payloads...)

    hash := crypto.Keccak256Hash(
        block.ProposerID.Hash[:],
        block.ParentHash[:],
        hashPosition[:],
        hashAcks[:],
        hashTimestamps[:],
        payloadHash[:])
    return hash, nil
}

func verifyBlockSignature(pubkey crypto.PublicKey,
    block *types.Block, sig crypto.Signature) (bool, error) {
    hash, err := hashBlock(block)
    if err != nil {
        return false, err
    }
    return pubkey.VerifySignature(hash, sig), nil
}

func hashVote(vote *types.Vote) common.Hash {
    binaryPeriod := make([]byte, 8)
    binary.LittleEndian.PutUint64(binaryPeriod, vote.Period)

    hashPosition := hashPosition(vote.Position)

    hash := crypto.Keccak256Hash(
        vote.ProposerID.Hash[:],
        vote.BlockHash[:],
        binaryPeriod,
        hashPosition[:],
        []byte{byte(vote.Type)},
    )
    return hash
}

func verifyVoteSignature(vote *types.Vote, sigToPub SigToPubFn) (bool, error) {
    hash := hashVote(vote)
    pubKey, err := sigToPub(hash, vote.Signature)
    if err != nil {
        return false, err
    }
    if vote.ProposerID != types.NewValidatorID(pubKey) {
        return false, nil
    }
    return true, nil
}

func hashCRS(block *types.Block, crs common.Hash) common.Hash {
    hashPos := hashPosition(block.Position)
    return crypto.Keccak256Hash(crs[:], hashPos[:])
}

func verifyCRSSignature(block *types.Block, crs common.Hash, sigToPub SigToPubFn) (
    bool, error) {
    hash := hashCRS(block, crs)
    pubKey, err := sigToPub(hash, block.CRSSignature)
    if err != nil {
        return false, err
    }
    if block.ProposerID != types.NewValidatorID(pubKey) {
        return false, nil
    }
    return true, nil
}

func hashPosition(position types.Position) common.Hash {
    binaryShardID := make([]byte, 4)
    binary.LittleEndian.PutUint32(binaryShardID, position.ShardID)

    binaryChainID := make([]byte, 4)
    binary.LittleEndian.PutUint32(binaryChainID, position.ChainID)

    binaryHeight := make([]byte, 8)
    binary.LittleEndian.PutUint64(binaryHeight, position.Height)

    return crypto.Keccak256Hash(
        binaryShardID,
        binaryChainID,
        binaryHeight,
    )
}