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

func signCompactionChainAck(block *types.Block,
    prv crypto.PrivateKey) (crypto.Signature, error) {
    hash, err := hashCompactionChainAck(block)
    if err != nil {
        return crypto.Signature{}, err
    }
    return prv.Sign(hash)
}

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

func hashBlock(blockConv types.BlockConverter) (common.Hash, error) {
    block := blockConv.Block()
    binaryHeight := make([]byte, 8)
    binary.LittleEndian.PutUint64(binaryHeight, block.Height)
    // 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(blockConv.Payloads()...)

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

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