Initial cloud-services repo - gateway service + pkg modules

pkg/security/encryptedstream.go

@@ -0,0 +1,98 @@
+package security
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+
+	"github.com/pkg/errors"
+)
+
+type IEncryptedStream interface {
+	Write(raw_data []byte) []byte
+	Read(raw_data []byte) ([]byte, error)
+}
+
+const blockSize = 4096
+const headerSize = 16
+
+type EncryptedStream struct {
+	gcm_encrypter  IEncryptor
+	header         []byte
+	header_applied bool
+}
+type StreamOption func(EncryptedStream) (EncryptedStream, error)
+
+func NewEncryptedStream(encryptor IEncryptor, options ...StreamOption) (IEncryptedStream, error) {
+	var err error
+	stream := EncryptedStream{gcm_encrypter: encryptor, header: nil, header_applied: false}
+	for _, option := range options {
+		stream, err = option(stream)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return &stream, nil
+}
+
+func WithUniqueId(uniqueid []byte) StreamOption {
+	return func(stream EncryptedStream) (EncryptedStream, error) {
+		if len(uniqueid) == headerSize {
+			stream.header = uniqueid
+			stream.header_applied = false
+			return stream, nil
+		}
+		return stream, errors.New("invalid file id - must be 16 bytes")
+	}
+}
+
+func (s *EncryptedStream) Write(rawData []byte) []byte {
+	var length = len(rawData)
+	highWatermark := 0
+	byteStream := make([]byte, 0)
+	index := 0
+	if !s.header_applied {
+		byteStream = append(byteStream, s.header...)
+		s.header_applied = true
+	}
+	for index < length {
+		highWatermark = int(math.Min(float64(length-index), float64(blockSize)))
+		slice := s.gcm_encrypter.EncryptChunk(rawData[index:highWatermark])
+		chunk_size := fmt.Sprintf("%04x", len(slice))
+		byteStream = append(byteStream, chunk_size...)
+		byteStream = append(byteStream, slice...)
+		index += highWatermark
+	}
+	return byteStream
+}
+
+func (s *EncryptedStream) Read(rawData []byte) ([]byte, error) {
+	var length int64 = int64(len(rawData))
+	byteStream := make([]byte, 0)
+	if !s.header_applied && length < headerSize {
+		return nil, errors.New("invalid stream")
+	}
+	var index int64 = 0
+
+	// read header
+	if !s.header_applied {
+		s.header = rawData[0:headerSize]
+		s.header_applied = true
+		index = headerSize
+	}
+	for index < length {
+		nextBlockSize := "0x" + string(rawData[index:index+4])
+		byte_slice_length, err := strconv.ParseInt(nextBlockSize, 0, 64)
+		if err != nil {
+			return nil, err
+		}
+		index += 4 // move index by 4 to actual data
+		slice, err := s.gcm_encrypter.DecryptChunk(rawData[index:(index + byte_slice_length)])
+		if err != nil {
+			return nil, err
+		}
+		byteStream = append(byteStream, slice...)
+		index += byte_slice_length
+	}
+	return byteStream, nil
+}