Added new io.Reader and io.WriteCloser interface to Decryption and Encryption respectively.

* added test case for streaming read/write
* bumped version#

crypt.go

@@ -79,7 +79,7 @@ func encrypt(args []string) {
 	}
 
 	var infd io.Reader = os.Stdin
-	var outfd io.Writer = os.Stdout
+	var outfd io.WriteCloser = os.Stdout
 	var inf *os.File
 
 	if len(args) > 1 {

sign/encrypt.go

@@ -84,6 +84,7 @@ type Encryptor struct {
 	started bool
 
 	buf    []byte
+	stream bool
 }
 
 // Create a new Encryption context and use the optional private key 'sk' for
@@ -150,7 +151,11 @@ func (e *Encryptor) AddRecipient(pk *PublicKey) error {
 }
 
 // Encrypt the input stream 'rd' and write encrypted stream to 'wr'
-func (e *Encryptor) Encrypt(rd io.Reader, wr io.Writer) error {
+func (e *Encryptor) Encrypt(rd io.Reader, wr io.WriteCloser) error {
+	if e.stream {
+		return fmt.Errorf("encrypt: can't use Encrypt() after using streaming I/O")
+	}
+
 	if !e.started {
 		err := e.start(wr)
 		if err != nil {
@@ -182,7 +187,8 @@ func (e *Encryptor) Encrypt(rd io.Reader, wr io.Writer) error {
 			i++
 		}
 	}
-	return nil
+
+	return wr.Close()
 }
 
 // Begin the encryption process by writing the header
@@ -283,6 +289,7 @@ type Decryptor struct {
 	// Decrypted key
 	key    []byte
 	eof    bool
+	stream bool
 }
 
 // Create a new decryption context and if 'pk' is given, check that it matches
@@ -420,8 +427,12 @@ func (d *Decryptor) Decrypt(wr io.Writer) error {
 		return fmt.Errorf("decrypt: wrapped-key not decrypted (missing SetPrivateKey()?")
 	}
 
+	if d.stream {
+		return fmt.Errorf("decrypt: can't use Decrypt() after using streaming I/O")
+	}
+
 	if d.eof {
-		return fmt.Errorf("decrypt: input stream has reached EOF")
+		return io.EOF
 	}
 
 	var i uint32
@@ -441,7 +452,6 @@ func (d *Decryptor) Decrypt(wr io.Writer) error {
 			d.eof = true
 			return nil
 		}
-
 	}
 	return nil
 }

sign/encrypt_test.go

@@ -22,6 +22,14 @@ import (
 	"testing"
 )
 
+type Buffer struct {
+	bytes.Buffer
+}
+
+func (b *Buffer) Close() error {
+	return nil
+}
+
 // one sender, one receiver no verification of sender
 func TestEncryptSimple(t *testing.T) {
 	assert := newAsserter(t)
@@ -45,7 +53,7 @@ func TestEncryptSimple(t *testing.T) {
 	assert(err == nil, "can't add recipient: %s", err)
 
 	rd := bytes.NewBuffer(buf)
-	wr := bytes.Buffer{}
+	wr := Buffer{}
 
 	err = ee.Encrypt(rd, &wr)
 	assert(err == nil, "encrypt fail: %s", err)
@@ -58,7 +66,7 @@ func TestEncryptSimple(t *testing.T) {
 	err = dd.SetPrivateKey(&receiver.Sec, nil)
 	assert(err == nil, "decryptor can't add SK: %s", err)
 
-	wr = bytes.Buffer{}
+	wr = Buffer{}
 	err = dd.Decrypt(&wr)
 	assert(err == nil, "decrypt fail: %s", err)
 
@@ -91,7 +99,7 @@ func TestEncryptCorrupted(t *testing.T) {
 	assert(err == nil, "can't add recipient: %s", err)
 
 	rd := bytes.NewReader(buf)
-	wr := bytes.Buffer{}
+	wr := Buffer{}
 
 	err = ee.Encrypt(rd, &wr)
 	assert(err == nil, "encrypt fail: %s", err)
@@ -136,7 +144,7 @@ func TestEncryptSenderVerified(t *testing.T) {
 	assert(err == nil, "can't add recipient: %s", err)
 
 	rd := bytes.NewBuffer(buf)
-	wr := bytes.Buffer{}
+	wr := Buffer{}
 
 	err = ee.Encrypt(rd, &wr)
 	assert(err == nil, "encrypt fail: %s", err)
@@ -149,7 +157,7 @@ func TestEncryptSenderVerified(t *testing.T) {
 	err = dd.SetPrivateKey(&receiver.Sec, &sender.Pub)
 	assert(err == nil, "decryptor can't add SK: %s", err)
 
-	wr = bytes.Buffer{}
+	wr = Buffer{}
 	err = dd.Decrypt(&wr)
 	assert(err == nil, "decrypt fail: %s", err)
 
@@ -190,7 +198,7 @@ func TestEncryptMultiReceiver(t *testing.T) {
 	}
 
 	rd := bytes.NewBuffer(buf)
-	wr := bytes.Buffer{}
+	wr := Buffer{}
 
 	err = ee.Encrypt(rd, &wr)
 	assert(err == nil, "encrypt fail: %s", err)
@@ -205,7 +213,7 @@ func TestEncryptMultiReceiver(t *testing.T) {
 		err = dd.SetPrivateKey(&rx[i].Sec, &sender.Pub)
 		assert(err == nil, "decryptor can't add SK %d: %s", i, err)
 
-		wr = bytes.Buffer{}
+		wr = Buffer{}
 		err = dd.Decrypt(&wr)
 		assert(err == nil, "decrypt %d fail: %s", i, err)
 
@@ -216,6 +224,88 @@ func TestEncryptMultiReceiver(t *testing.T) {
 	}
 }
 
+// Test stream write and read
+func TestStreamIO(t *testing.T) {
+	assert := newAsserter(t)
+
+	receiver, err := NewKeypair()
+	assert(err == nil, "receiver keypair gen failed: %s", err)
+
+	var blkSize int = 1024
+	var size int = (blkSize * 10)
+
+	// cleartext
+	buf := make([]byte, size)
+	for i := 0; i < len(buf); i++ {
+		buf[i] = byte(i & 0xff)
+	}
+
+	ee, err := NewEncryptor(nil, uint64(blkSize))
+	assert(err == nil, "encryptor create fail: %s", err)
+
+	err = ee.AddRecipient(&receiver.Pub)
+	assert(err == nil, "can't add recipient: %s", err)
+
+	wr := Buffer{}
+	wio, err := ee.NewStreamWriter(&wr)
+	assert(err == nil, "can't start stream writer: %s", err)
+
+	// chunksize for writing to stream
+	csize := 19
+	rbuf := buf
+	for len(rbuf) > 0 {
+		m := csize
+		if len(rbuf) < m {
+			m = len(rbuf)
+		}
+
+		n, err := wio.Write(rbuf[:m])
+		assert(err == nil, "stream write failed: %s", err)
+		assert(n == m, "stream write mismatch: exp %d, saw %d", m, n)
+
+		rbuf = rbuf[m:]
+	}
+	err = wio.Close()
+	assert(err == nil, "stream close failed: %s", err)
+
+	_, err = wio.Write(buf[:csize])
+	assert(err != nil, "stream write accepted I/O after close: %s", err)
+
+	rd := bytes.NewBuffer(wr.Bytes())
+
+	dd, err := NewDecryptor(rd)
+	assert(err == nil, "decryptor create fail: %s", err)
+
+	err = dd.SetPrivateKey(&receiver.Sec, nil)
+	assert(err == nil, "decryptor can't add SK: %s", err)
+
+	rio, err := dd.NewStreamReader()
+	assert(err == nil, "stream reader failed: %s", err)
+
+	rbuf = make([]byte, csize)
+	wr = Buffer{}
+	n := 0
+	for {
+		m, err := rio.Read(rbuf)
+		assert(err == nil || err == io.EOF, "streamread fail: %s", err)
+
+		if m > 0 {
+			wr.Write(rbuf[:m])
+			n += m
+		}
+		if err == io.EOF || m == 0 {
+			break
+		}
+	}
+
+	b := wr.Bytes()
+	assert(n == len(b), "streamread: bad buflen; exp %d, saw %d", n, len(b))
+	assert(n == len(buf), "streamread: decrypt len mismatch; exp %d, saw %d", len(buf), n)
+
+	assert(byteEq(b, buf), "decrypt content mismatch")
+
+}
+
 func randint() int {
 	var b [4]byte
 

sign/stream.go

@@ -0,0 +1,164 @@
+// stream.go - Streaming io.Reader, io.Writer interface to encryption/decryption
+//
+// (c) 2016 Sudhi Herle <sudhi@herle.net>
+//
+// Licensing Terms: GPLv2
+//
+// If you need a commercial license for this work, please contact
+// the author.
+//
+// This software does not come with any express or implied
+// warranty; it is provided "as is". No claim  is made to its
+// suitability for any purpose.
+//
+
+package sign
+
+import (
+	"errors"
+	"fmt"
+	"io"
+)
+
+// encWriter buffers partial writes until a full chunk is accumulated.
+// It's methods implement the io.WriteCloser interface.
+type encWriter struct {
+	buf []byte
+	n   int // # of bytes written
+	wr  io.WriteCloser
+	e   *Encryptor
+	blk uint32
+	err error
+}
+
+// NewStreamWriter begins stream encryption to an underlying destination writer 'wr'.
+// It returns an io.WriteCloser.
+func (e *Encryptor) NewStreamWriter(wr io.WriteCloser) (io.WriteCloser, error) {
+	if !e.started {
+		err := e.start(wr)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	w := &encWriter{
+		buf: make([]byte, e.ChunkSize),
+		wr:  wr,
+		e:   e,
+	}
+
+	e.stream = true
+	return w, nil
+}
+
+// Write implements the io.Writer interface
+func (w *encWriter) Write(b []byte) (int, error) {
+	if w.err != nil {
+		return 0, w.err
+	}
+
+	n := len(b)
+	if n == 0 {
+		return 0, nil
+	}
+
+	max := int(w.e.ChunkSize)
+	for len(b) > 0 {
+		buf := w.buf[w.n:]
+		z := copy(buf, b)
+		b = b[z:]
+		w.n += z
+
+		// We only flush if we have more data remaining in the input buffer.
+		// This way, we don't flush a potentially last block here; that happens
+		// when the caller eventually closes the stream.
+		if w.n == max && len(b) > 0 {
+			w.err = w.e.encrypt(w.buf, w.wr, w.blk, false)
+			if w.err != nil {
+				return 0, w.err
+			}
+
+			w.n = 0
+			w.blk += 1
+		}
+	}
+	return n, nil
+}
+
+// Close implements the io.Close interface
+func (w *encWriter) Close() error {
+	if w.err != nil {
+		return w.err
+	}
+
+	err := w.e.encrypt(w.buf[:w.n], w.wr, w.blk, true)
+	if err != nil {
+		w.err = err
+		return err
+	}
+
+	w.n = 0
+	w.err = errClosed
+	return w.wr.Close()
+}
+
+// encReader buffers partial reads and it's methods implement the io.Reader interface.
+type encReader struct {
+	buf    []byte
+	unread []byte
+	d      *Decryptor
+	blk    uint32
+}
+
+// NewStreamReader returns an io.Reader to read from the decrypted stream
+func (d *Decryptor) NewStreamReader() (io.Reader, error) {
+	if d.key == nil {
+		return nil, fmt.Errorf("streamReader: wrapped-key not decrypted (missing SetPrivateKey()?")
+	}
+
+	if d.eof {
+		return nil, io.EOF
+	}
+
+	d.stream = true
+	return &encReader{
+		buf: make([]byte, d.ChunkSize),
+		d:   d,
+	}, nil
+}
+
+// Read implements io.Reader interface
+func (r *encReader) Read(b []byte) (int, error) {
+	if r.d.eof && len(r.unread) == 0 {
+		return 0, io.EOF
+	}
+
+	if len(r.unread) > 0 {
+		n := copy(b, r.unread)
+		r.unread = r.unread[n:]
+		return n, nil
+	}
+
+	buf, eof, err := r.d.decrypt(r.blk)
+	if err != nil {
+		return 0, err
+	}
+
+	r.blk += 1
+
+	n := copy(b, buf)
+	buf = buf[n:]
+
+	copy(r.buf, buf)
+	r.unread = r.buf[:len(buf)]
+
+	if eof {
+		r.d.eof = true
+	}
+
+	return n, nil
+}
+
+var (
+	errClosed = errors.New("encrypt: stream already closed")
+)

version

@@ -1 +1 @@
-0.8.1
+0.9.0