Golang secretbox.Open函數代碼示例

func (kx *KeyExchange) exchange2() ([]byte, error) {
	reply, err := kx.meetingPlace.Exchange(kx.Log, kx.meeting2[:], kx.message2[:], kx.ShutdownChan)
	if err != nil {
		return nil, err
	}

	var nonce [24]byte
	if len(reply) < len(nonce) {
		return nil, errors.New("panda: meeting point reply too small")
	}

	if kx.sharedKey[0] == 0 && kx.sharedKey[1] == 0 {
		panic("here")
	}
	copy(nonce[:], reply)
	message, ok := secretbox.Open(nil, reply[24:], &nonce, &kx.sharedKey)
	if !ok {
		return nil, errors.New("panda: peer's message cannot be authenticated")
	}

	if len(message) < 4 {
		return nil, errors.New("panda: peer's message is invalid")
	}
	l := binary.LittleEndian.Uint32(message)
	message = message[4:]
	if l > uint32(len(message)) {
		return nil, errors.New("panda: peer's message is truncated")
	}
	message = message[:int(l)]
	return message, nil
}

// OpenWithKey is the same as Open, but a different key can be passed in.
func (s *Service) OpenWithKey(e *SealedBytes, secretKey *[SecretKeyLength]byte) (byt []byte, err error) {
	// once function is complete, check if we are returning err or not.
	// if we are, return emit a failure metric, if not a success metric.
	defer func() {
		if err == nil {
			s.metricsClient.Inc("success", 1, 1)
		} else {
			s.metricsClient.Inc("failure", 1, 1)
		}
	}()

	// check that we either initialized with a key or one was passed in
	if secretKey == nil {
		return nil, fmt.Errorf("secret key is nil")
	}

	// convert nonce to an array
	nonce, err := nonceSliceToArray(e.Nonce)
	if err != nil {
		return nil, err
	}

	// decrypt
	var decrypted []byte
	decrypted, ok := secretbox.Open(decrypted, e.Ciphertext, nonce, secretKey)
	if !ok {
		return nil, fmt.Errorf("unable to decrypt message")
	}

	return decrypted, nil
}

func (nd *NaClDecryptor) decrypt(buf []byte) ([]byte, bool) {
	seqNoAndDF := binary.BigEndian.Uint64(buf[:8])
	df := (seqNoAndDF & (1 << 63)) != 0
	seqNo := seqNoAndDF & ((1 << 63) - 1)
	var di *NaClDecryptorInstance
	if df {
		di = nd.instanceDF
	} else {
		di = nd.instance
	}
	binary.BigEndian.PutUint64(di.nonce[16:24], seqNoAndDF)
	result, success := secretbox.Open(nil, buf[8:], &di.nonce, nd.sessionKey)
	if !success {
		return nil, false
	}
	// Drop duplicates. We do this *after* decryption since we must
	// not advance our state unless decryption succeeded. Doing so
	// would open an easy attack vector where an adversary could
	// inject a packet with a sequence number of (1 << 63) - 1,
	// causing all subsequent genuine packets to get dropped.
	offset, usedOffsets := di.advanceState(seqNo)
	if usedOffsets == nil || usedOffsets.Contains(offset) {
		// We have detected a possible replay attack, but it is
		// possible we may have just received a very old packet, or
		// duplication may have occurred in the network. So let's just
		// drop the packet silently.
		return nil, true
	}
	usedOffsets.Add(offset)
	return result, success
}

func (receiver *EncryptedTCPReceiver) Decode(msg []byte) ([]byte, error) {
	decodedMsg, success := secretbox.Open(nil, msg, &receiver.state.nonce, receiver.state.sessionKey)
	if !success {
		return nil, fmt.Errorf("Unable to decrypt TCP msg")
	}
	receiver.state.advance()
	return decodedMsg, nil
}

// decrypt extracts the nonce from the ciphertext, and attempts to
// decrypt with NaCl's secretbox.
func decrypt(key *[keySize]byte, in []byte) ([]byte, bool) {
	if len(in) < nonceSize {
		return nil, false
	}
	var nonce [nonceSize]byte
	copy(nonce[:], in)
	return secretbox.Open(nil, in[nonceSize:], &nonce, key)
}

// trySavedKeys tries to decrypt ciphertext using keys saved for missing messages.
func (r *Ratchet) trySavedKeys(ciphertext []byte) ([]byte, error) {
	if len(ciphertext) < sealedHeaderSize {
		return nil, errors.New("ratchet: header too small to be valid")
	}

	sealedHeader := ciphertext[:sealedHeaderSize]
	var nonce [24]byte
	copy(nonce[:], sealedHeader)
	sealedHeader = sealedHeader[len(nonce):]

	for headerKey, messageKeys := range r.saved {
		header, ok := secretbox.Open(nil, sealedHeader, &nonce, &headerKey)
		if !ok {
			continue
		}
		if len(header) != headerSize {
			continue
		}
		msgNum := binary.LittleEndian.Uint32(header[:4])
		msgKey, ok := messageKeys[msgNum]
		if !ok {
			// This is a fairly common case: the message key might
			// not have been saved because it's the next message
			// key.
			return nil, nil
		}

		sealedMessage := ciphertext[sealedHeaderSize:]
		copy(nonce[:], header[nonceInHeaderOffset:])
		msg, ok := secretbox.Open(nil, sealedMessage, &nonce, &msgKey.key)
		if !ok {
			return nil, errors.New("ratchet: corrupt message")
		}
		delete(messageKeys, msgNum)
		if len(messageKeys) == 0 {
			delete(r.saved, headerKey)
		}
		return msg, nil
	}

	return nil, nil
}

func (c *Conn) Read(out []byte) (n int, err error) {
	if len(c.readPending) > 0 {
		n = copy(out, c.readPending)
		c.readPending = c.readPending[n:]
		return
	}

	if c.readBuffer == nil {
		c.readBuffer = make([]byte, blockSize+2)
	}

	if _, err := io.ReadFull(c.conn, c.readBuffer[:2]); err != nil {
		return 0, err
	}
	n = int(c.readBuffer[0]) | int(c.readBuffer[1])<<8
	if n > len(c.readBuffer) {
		return 0, errors.New("transport: peer's message too large for Read")
	}
	if _, err := io.ReadFull(c.conn, c.readBuffer[:n]); err != nil {
		return 0, err
	}

	var ok bool
	if len(out) >= n-secretbox.Overhead {
		// We can decrypt directly into the output buffer.
		out, ok = secretbox.Open(out[:0], c.readBuffer[:n], &c.readSequence, &c.readKey)
		n = len(out)
	} else {
		// We need to decrypt into a side buffer and copy a prefix of
		// the result into the caller's buffer.
		c.decryptBuffer, ok = secretbox.Open(c.decryptBuffer[:0], c.readBuffer[:n], &c.readSequence, &c.readKey)
		n = copy(out, c.decryptBuffer)
		c.readPending = c.decryptBuffer[n:]
	}
	incSequence(&c.readSequence)
	if !ok {
		c.readPending = c.readPending[:0]
		return 0, errors.New("transport: bad MAC")
	}

	return
}

func (c *Conn) decrypt(data []byte) ([]byte, error) {
	if !c.readKeyValid {
		return data, nil
	}

	decrypted, ok := secretbox.Open(nil, data, &c.readSequence, &c.readKey)
	incSequence(&c.readSequence)
	if !ok {
		return nil, errors.New("transport: bad MAC")
	}
	return decrypted, nil
}

func decrypt(key, ciphertext []byte) ([]byte, error) {
	if len(ciphertext) < nonceLen+secretbox.Overhead {
		return nil, fmt.Errorf("message too short")
	}
	var nonce [nonceLen]byte
	copy(nonce[:], ciphertext)
	ciphertext = ciphertext[nonceLen:]
	text, ok := secretbox.Open(nil, ciphertext, &nonce, makeKey(key))
	if !ok {
		return nil, fmt.Errorf("decryption failure")
	}
	return text, nil
}

// Decrypt decrypts a message using XSalsa20-Poly1305 and outputs it to dst.
// Returns false if decryption failed (authentication tag mismatch).
func (sb *secretBoxMode) Decrypt(dst []byte, src []byte, nonce []byte) bool {
	if len(src) <= sb.Overhead() {
		panic("cryptstate: bad src")
	}

	if len(nonce) != 24 {
		panic("cryptstate: bad nonce length")
	}

	noncePtr := (*[24]byte)(unsafe.Pointer(&nonce[0]))
	_, ok := secretbox.Open(dst[0:0], src, noncePtr, &sb.key)
	return ok
}

func DecryptPrefixNonce(ciphertxt []byte, secret *[32]byte) ([]byte, bool) {
	if len(ciphertxt) < secretbox.Overhead+24 {
		return nil, false
	}
	// There is no way to nicely convert from a slice to an
	// array. So have to used the following loop.
	var nonce [24]byte
	for idx, e := range ciphertxt[0:24] {
		nonce[idx] = e
	}
	ciphertxt = ciphertxt[24:]
	return secretbox.Open(nil, ciphertxt, &nonce, secret)
}

// TODO : consider caching the last deciphered chunk
func (this *CipherReaderAt) ReadAt(p []byte, off int64) (n int, err error) {
	log.Printf("ReadAt len(p):%v, off:%v\n", len(p), off)
	// read Nonce if not yet read
	if this.Nonce == nil {
		this.Nonce = &[24]byte{}
		_, err := this.Reader.ReadAt(this.Nonce[:], 0)
		if err != nil {
			return 0, err
		}
	}
	// ...
	for len(p) > 0 {
		chunkIndex := off / (this.ChunkSize - secretbox.Overhead)
		chunkStart := chunkIndex * this.ChunkSize
		offChunk := off - chunkIndex*(this.ChunkSize-secretbox.Overhead)
		log.Printf(" - chunkIndex: %v, chunkStart: %v, offChunk: %v\n", chunkIndex, chunkStart, offChunk)

		// compute nonce, basically a base 256 addition operation
		var nonce [24]byte
		copy(nonce[:], this.Nonce[:])
		{
			ci := chunkIndex // copy
			i := 0
			carry := int16(0)
			for ci > 0 || carry > 0 {
				sum := int16(ci % 256)
				sum += int16(nonce[i])
				sum += int16(carry)
				nonce[i] = byte(sum % 256)
				carry = int16(sum >> 8)
				ci >>= 8
				i++
			}
			log.Printf(" - nonce: %v", nonce)
		}
		numRead, err := this.Reader.ReadAt(this.Chunk, 24+chunkStart)
		if err != nil && err != io.EOF {
			return n, err
		}
		openedChunk, ok := secretbox.Open(nil, this.Chunk[:numRead], &nonce, this.Key)
		//fmt.Println(colors.Cyan("nonce:", nonce, " key:", this.Key, " numRead:", numRead))
		if !ok {
			return n, errors.New(fmt.Sprintf("Failed to decipher chunk %v", chunkIndex))
		}
		copied := copy(p, openedChunk[offChunk:])
		p = p[copied:]
		n += copied
		off += int64(copied)
	}
	return n, nil
}

func (s *Convergent) Get(key []byte) ([]byte, error) {
	boxedkey := s.computeBoxedKey(key)
	box, err := s.untrusted.Get(boxedkey)
	if err != nil {
		return nil, err
	}

	nonce := s.makeNonce(key)
	plain, ok := secretbox.Open(nil, box, nonce, s.secret)
	if !ok {
		return nil, Corrupt{Key: key}
	}
	return plain, nil
}

// decrypt extracts the nonce from the ciphertext, and attempts to
// decrypt with NaCl's secretbox.
func decrypt(key *[keySize]byte, message []byte) ([]byte, error) {
	if len(message) < (nonceSize + secretbox.Overhead) {
		return nil, ErrDecrypt
	}

	var nonce [nonceSize]byte
	copy(nonce[:], message[:nonceSize])
	out, ok := secretbox.Open(nil, message[nonceSize:], &nonce, key)
	if !ok {
		return nil, ErrDecrypt
	}

	return out, nil
}

func unbox(key *[32]byte, body []byte) ([]byte, error) {
	var nonce [24]byte
	if len(body) < len(nonce)+secretbox.Overhead+2 {
		return nil, errors.New("panda: reply from server is too short to be valid")
	}
	copy(nonce[:], body)
	unsealed, ok := secretbox.Open(nil, body[len(nonce):], &nonce, key)
	if !ok {
		return nil, errors.New("panda: failed to authenticate reply from server")
	}
	l := int(unsealed[0]) | int(unsealed[1])<<8
	unsealed = unsealed[2:]
	if l > len(unsealed) {
		return nil, errors.New("panda: corrupt but authentic message found")
	}
	return unsealed[:l], nil
}