diff --git a/crypto/crypto.go b/crypto/crypto.go
index 482a5a748..6bca758ac 100644
--- a/crypto/crypto.go
+++ b/crypto/crypto.go
@@ -1,16 +1,12 @@
 package crypto
 
 import (
-	"bytes"
 	"crypto/aes"
 	"crypto/cipher"
 	"crypto/rand"
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io"
-	"io/ioutil"
-	"sync"
 
 	"github.com/restic/restic/chunker"
 	"golang.org/x/crypto/poly1305"
@@ -300,194 +296,3 @@ func KDF(N, R, P int, salt []byte, password string) (*Key, error) {
 
 	return derKeys, nil
 }
-
-type encryptWriter struct {
-	iv      iv
-	wroteIV bool
-	data    *bytes.Buffer
-	key     *Key
-	s       cipher.Stream
-	w       io.Writer
-	origWr  io.Writer
-	err     error // remember error writing iv
-}
-
-func (e *encryptWriter) Close() error {
-	// write mac
-	mac := poly1305_sign(e.data.Bytes()[ivSize:], e.data.Bytes()[:ivSize], &e.key.Sign)
-	_, err := e.origWr.Write(mac)
-	if err != nil {
-		return err
-	}
-
-	// return buffer
-	bufPool.Put(e.data.Bytes())
-
-	return nil
-}
-
-const encryptWriterChunkSize = 512 * 1024 // 512 KiB
-var encryptWriterBufPool = sync.Pool{
-	New: func() interface{} {
-		return make([]byte, encryptWriterChunkSize)
-	},
-}
-
-func (e *encryptWriter) Write(p []byte) (int, error) {
-	// write iv first
-	if !e.wroteIV {
-		_, e.err = e.origWr.Write(e.iv[:])
-		e.wroteIV = true
-	}
-
-	if e.err != nil {
-		return 0, e.err
-	}
-
-	buf := encryptWriterBufPool.Get().([]byte)
-	defer encryptWriterBufPool.Put(buf)
-
-	written := 0
-	for len(p) > 0 {
-		max := len(p)
-		if max > encryptWriterChunkSize {
-			max = encryptWriterChunkSize
-		}
-
-		e.s.XORKeyStream(buf, p[:max])
-		n, err := e.w.Write(buf[:max])
-		if n != max {
-			if err == nil { // should never happen
-				err = io.ErrShortWrite
-			}
-		}
-
-		written += n
-		p = p[n:]
-
-		if err != nil {
-			e.err = err
-			return written, err
-		}
-	}
-
-	return written, nil
-}
-
-// EncryptTo buffers data written to the returned io.WriteCloser. When Close()
-// is called, the data is encrypted an written to the underlying writer.
-func EncryptTo(ks *Key, wr io.Writer) io.WriteCloser {
-	ew := &encryptWriter{
-		iv:     newIV(),
-		data:   bytes.NewBuffer(getBuffer()[:0]),
-		key:    ks,
-		origWr: wr,
-	}
-
-	// buffer iv for mac
-	_, err := ew.data.Write(ew.iv[:])
-	if err != nil {
-		panic(err)
-	}
-
-	c, err := aes.NewCipher(ks.Encrypt[:])
-	if err != nil {
-		panic(fmt.Sprintf("unable to create cipher: %v", err))
-	}
-
-	ew.s = cipher.NewCTR(c, ew.iv[:])
-	ew.w = io.MultiWriter(ew.data, wr)
-
-	return ew
-}
-
-type decryptReader struct {
-	buf []byte
-	pos int
-}
-
-func (d *decryptReader) Read(dst []byte) (int, error) {
-	if d.buf == nil {
-		return 0, io.EOF
-	}
-
-	if len(dst) == 0 {
-		return 0, nil
-	}
-
-	remaining := len(d.buf) - d.pos
-	if len(dst) >= remaining {
-		n := copy(dst, d.buf[d.pos:])
-		d.Close()
-		return n, io.EOF
-	}
-
-	n := copy(dst, d.buf[d.pos:d.pos+len(dst)])
-	d.pos += n
-
-	return n, nil
-}
-
-func (d *decryptReader) ReadByte() (c byte, err error) {
-	if d.buf == nil {
-		return 0, io.EOF
-	}
-
-	remaining := len(d.buf) - d.pos
-	if remaining == 1 {
-		c = d.buf[d.pos]
-		d.Close()
-		return c, io.EOF
-	}
-
-	c = d.buf[d.pos]
-	d.pos++
-
-	return
-}
-
-func (d *decryptReader) Close() error {
-	if d.buf == nil {
-		return nil
-	}
-
-	freeBuffer(d.buf)
-	d.buf = nil
-	return nil
-}
-
-// DecryptFrom verifies and decrypts the ciphertext read from rd with ks and
-// makes it available on the returned Reader. Ciphertext must be in the form IV
-// || Ciphertext || MAC. In order to correctly verify the ciphertext, rd is
-// drained, locally buffered and made available on the returned Reader
-// afterwards. If a MAC verification failure is observed, it is returned
-// immediately.
-func DecryptFrom(ks *Key, rd io.Reader) (io.ReadCloser, error) {
-	ciphertext := getBuffer()
-
-	ciphertext = ciphertext[0:cap(ciphertext)]
-	n, err := io.ReadFull(rd, ciphertext)
-	if err != io.ErrUnexpectedEOF {
-		// read remaining data
-		buf, e := ioutil.ReadAll(rd)
-		ciphertext = append(ciphertext, buf...)
-		n += len(buf)
-		err = e
-	} else {
-		err = nil
-	}
-
-	if err != nil {
-		return nil, err
-	}
-
-	ciphertext = ciphertext[:n]
-
-	// decrypt
-	ciphertext, err = Decrypt(ks, ciphertext, ciphertext)
-	if err != nil {
-		return nil, err
-	}
-
-	return &decryptReader{buf: ciphertext}, nil
-}
diff --git a/crypto/reader.go b/crypto/reader.go
new file mode 100644
index 000000000..87856ef0a
--- /dev/null
+++ b/crypto/reader.go
@@ -0,0 +1,97 @@
+package crypto
+
+import (
+	"io"
+	"io/ioutil"
+)
+
+type decryptReader struct {
+	buf []byte
+	pos int
+}
+
+func (d *decryptReader) Read(dst []byte) (int, error) {
+	if d.buf == nil {
+		return 0, io.EOF
+	}
+
+	if len(dst) == 0 {
+		return 0, nil
+	}
+
+	remaining := len(d.buf) - d.pos
+	if len(dst) >= remaining {
+		n := copy(dst, d.buf[d.pos:])
+		d.Close()
+		return n, io.EOF
+	}
+
+	n := copy(dst, d.buf[d.pos:d.pos+len(dst)])
+	d.pos += n
+
+	return n, nil
+}
+
+func (d *decryptReader) ReadByte() (c byte, err error) {
+	if d.buf == nil {
+		return 0, io.EOF
+	}
+
+	remaining := len(d.buf) - d.pos
+	if remaining == 1 {
+		c = d.buf[d.pos]
+		d.Close()
+		return c, io.EOF
+	}
+
+	c = d.buf[d.pos]
+	d.pos++
+
+	return
+}
+
+func (d *decryptReader) Close() error {
+	if d.buf == nil {
+		return nil
+	}
+
+	freeBuffer(d.buf)
+	d.buf = nil
+	return nil
+}
+
+// DecryptFrom verifies and decrypts the ciphertext read from rd with ks and
+// makes it available on the returned Reader. Ciphertext must be in the form IV
+// || Ciphertext || MAC. In order to correctly verify the ciphertext, rd is
+// drained, locally buffered and made available on the returned Reader
+// afterwards. If a MAC verification failure is observed, it is returned
+// immediately.
+func DecryptFrom(ks *Key, rd io.Reader) (io.ReadCloser, error) {
+	ciphertext := getBuffer()
+
+	ciphertext = ciphertext[0:cap(ciphertext)]
+	n, err := io.ReadFull(rd, ciphertext)
+	if err != io.ErrUnexpectedEOF {
+		// read remaining data
+		buf, e := ioutil.ReadAll(rd)
+		ciphertext = append(ciphertext, buf...)
+		n += len(buf)
+		err = e
+	} else {
+		err = nil
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	ciphertext = ciphertext[:n]
+
+	// decrypt
+	ciphertext, err = Decrypt(ks, ciphertext, ciphertext)
+	if err != nil {
+		return nil, err
+	}
+
+	return &decryptReader{buf: ciphertext}, nil
+}
diff --git a/crypto/writer.go b/crypto/writer.go
new file mode 100644
index 000000000..856fb5fff
--- /dev/null
+++ b/crypto/writer.go
@@ -0,0 +1,110 @@
+package crypto
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"fmt"
+	"io"
+	"sync"
+)
+
+type encryptWriter struct {
+	iv      iv
+	wroteIV bool
+	data    *bytes.Buffer
+	key     *Key
+	s       cipher.Stream
+	w       io.Writer
+	origWr  io.Writer
+	err     error // remember error writing iv
+}
+
+func (e *encryptWriter) Close() error {
+	// write mac
+	mac := poly1305_sign(e.data.Bytes()[ivSize:], e.data.Bytes()[:ivSize], &e.key.Sign)
+	_, err := e.origWr.Write(mac)
+	if err != nil {
+		return err
+	}
+
+	// return buffer
+	bufPool.Put(e.data.Bytes())
+
+	return nil
+}
+
+const encryptWriterChunkSize = 512 * 1024 // 512 KiB
+var encryptWriterBufPool = sync.Pool{
+	New: func() interface{} {
+		return make([]byte, encryptWriterChunkSize)
+	},
+}
+
+func (e *encryptWriter) Write(p []byte) (int, error) {
+	// write iv first
+	if !e.wroteIV {
+		_, e.err = e.origWr.Write(e.iv[:])
+		e.wroteIV = true
+	}
+
+	if e.err != nil {
+		return 0, e.err
+	}
+
+	buf := encryptWriterBufPool.Get().([]byte)
+	defer encryptWriterBufPool.Put(buf)
+
+	written := 0
+	for len(p) > 0 {
+		max := len(p)
+		if max > encryptWriterChunkSize {
+			max = encryptWriterChunkSize
+		}
+
+		e.s.XORKeyStream(buf, p[:max])
+		n, err := e.w.Write(buf[:max])
+		if n != max {
+			if err == nil { // should never happen
+				err = io.ErrShortWrite
+			}
+		}
+
+		written += n
+		p = p[n:]
+
+		if err != nil {
+			e.err = err
+			return written, err
+		}
+	}
+
+	return written, nil
+}
+
+// EncryptTo buffers data written to the returned io.WriteCloser. When Close()
+// is called, the data is encrypted an written to the underlying writer.
+func EncryptTo(ks *Key, wr io.Writer) io.WriteCloser {
+	ew := &encryptWriter{
+		iv:     newIV(),
+		data:   bytes.NewBuffer(getBuffer()[:0]),
+		key:    ks,
+		origWr: wr,
+	}
+
+	// buffer iv for mac
+	_, err := ew.data.Write(ew.iv[:])
+	if err != nil {
+		panic(err)
+	}
+
+	c, err := aes.NewCipher(ks.Encrypt[:])
+	if err != nil {
+		panic(fmt.Sprintf("unable to create cipher: %v", err))
+	}
+
+	ew.s = cipher.NewCTR(c, ew.iv[:])
+	ew.w = io.MultiWriter(ew.data, wr)
+
+	return ew
+}