signature.go

// Copyright 2021 Star Inc.(https://starinc.xyz)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package KaguyaKernel

import (
	"crypto/sha256"
	"encoding/json"
	"fmt"
	"gopkg.in/star-inc/kaguyakernel.v2/time"
)

type Signature struct {
	Data      []byte        `json:"data"`
	Salt      string        `json:"salt"`
	Timestamp time.NanoTime `json:"timestamp"`
	Method    string        `json:"method,omitempty"`
}

// NewSignature will Generate a Signature as hex string by SHA256.
// Due to the data has been turned into compressed bytes,
// there will be no JSON ordering problem while doing the verification.
func NewSignature(session *Session, currentTimestamp time.NanoTime, method string, dataBytes []byte) *Signature {
	instance := new(Signature)
	instance.Data = dataBytes
	instance.Method = method
	instance.Salt = session.requestSalt
	instance.Timestamp = currentTimestamp
	return instance
}

// JSONHashHex will generate a hex after hashing the JSON signature.
func (s *Signature) JSONHashHex() (string, error) {
	signatureString, err := json.Marshal(s)
	if err != nil {
		return "", err
	}
	signatureHash := sha256.Sum256(signatureString)
	return fmt.Sprintf("%x", signatureHash), nil
}