diff options
Diffstat (limited to 'oae.go')
| -rw-r--r-- | oae.go | 96 |
1 files changed, 36 insertions, 60 deletions
@@ -7,7 +7,6 @@ import ( "crypto/cipher" "crypto/rand" "errors" - "fmt" "io" ) @@ -15,49 +14,22 @@ const ( nonceSize = 12 aeadOverhead = 16 - defaultSegmentSize = 1024 * 1024 + segmentSize = 1024 * 1024 + plaintextSegmentSize = segmentSize - aeadOverhead - defaultSaltSize = 32 + saltSize = 32 ) -//go:generate go tool stringer -type=encryptionAlg -linecomment -type encryptionAlg int8 - -const ( - encryptionAlgInvalid encryptionAlg = iota - encryptionAlgAES256_GCM // AES-256-GCM -) - -type encryptionMetadata struct { - EncryptionType encryptionAlg - SegmentSize int32 -} - -func (e *encryptionMetadata) validate() error { - if e.EncryptionType != encryptionAlgAES256_GCM { - return fmt.Errorf("invalid encryption alg %q", e.EncryptionType) - } - if e.SegmentSize <= 0 || e.SegmentSize > defaultSegmentSize { - return fmt.Errorf("segment size too long") - } - return nil -} - -func (e *encryptionMetadata) plaintextSegmentSize() int { - return int(e.SegmentSize) - aeadOverhead -} - type segmentEncrypter struct { - hashMetadata hashMetadata - encryptionMetadata encryptionMetadata - password string + password string + iterations int aead cipher.AEAD nonce [nonceSize]byte } func (se *segmentEncrypter) initialize(salt []byte) error { - key, err := se.hashMetadata.hashPassword(se.password, salt) + key, err := hashPassword(se.password, salt, se.iterations) if err != nil { return err } @@ -111,13 +83,12 @@ type encryptingWriter struct { initialized bool } -func (e *encryptionMetadata) newEncryptingWriter(w io.Writer, password string, passwordMetadata *hashMetadata) *encryptingWriter { +func newEncryptingWriter(w io.Writer, password string, iterations int) *encryptingWriter { return &encryptingWriter{ w: w, encrypter: segmentEncrypter{ - hashMetadata: *passwordMetadata, - encryptionMetadata: *e, - password: password, + password: password, + iterations: iterations, }, } } @@ -126,7 +97,7 @@ func (w *encryptingWriter) initialize() error { if w.initialized { return nil } - header := make([]byte, w.encrypter.hashMetadata.SaltSize) + header := make([]byte, saltSize) rand.Read(header) if err := w.encrypter.initialize(header); err != nil { return err @@ -134,7 +105,7 @@ func (w *encryptingWriter) initialize() error { if _, err := w.w.Write(header); err != nil { return err } - w.buf = make([]byte, 0, w.encrypter.encryptionMetadata.SegmentSize) + w.buf = make([]byte, 0, segmentSize) w.initialized = true return nil } @@ -157,12 +128,12 @@ func (w *encryptingWriter) Write(buf []byte) (int, error) { } nn := 0 for len(buf) > 0 { - if len(w.buf) == w.encrypter.encryptionMetadata.plaintextSegmentSize() { + if len(w.buf) == plaintextSegmentSize { if err := w.writeBuf(false); err != nil { return nn, err } } - n := copy(w.buf[len(w.buf):w.encrypter.encryptionMetadata.plaintextSegmentSize()], buf) + n := copy(w.buf[len(w.buf):plaintextSegmentSize], buf) nn += n w.buf = w.buf[:len(w.buf)+n] buf = buf[n:] @@ -183,7 +154,7 @@ func (w *encryptingWriter) ReadFrom(r io.Reader) (int64, error) { } var nn int64 for { - n, err := io.ReadFull(r, w.buf[len(w.buf):w.encrypter.encryptionMetadata.plaintextSegmentSize()+1]) + n, err := io.ReadFull(r, w.buf[len(w.buf):plaintextSegmentSize+1]) nn += int64(n) w.buf = w.buf[:len(w.buf)+n] if err != nil { @@ -192,8 +163,8 @@ func (w *encryptingWriter) ReadFrom(r io.Reader) (int64, error) { } return nn, err } - nextByte := w.buf[w.encrypter.encryptionMetadata.plaintextSegmentSize()] - w.buf = w.buf[:w.encrypter.encryptionMetadata.plaintextSegmentSize()] + nextByte := w.buf[plaintextSegmentSize] + w.buf = w.buf[:plaintextSegmentSize] if err := w.writeBuf(false); err != nil { return nn, err } @@ -203,19 +174,19 @@ func (w *encryptingWriter) ReadFrom(r io.Reader) (int64, error) { } type decryptingReader struct { - r *bufio.Reader - decrypter segmentEncrypter - buf bytes.Buffer - initialized bool + r *bufio.Reader + decrypter segmentEncrypter + buf bytes.Buffer + initialized bool + readFinalBlock bool } -func (e *encryptionMetadata) newDecryptingReader(r io.Reader, password string, passwordMetadata *hashMetadata) *decryptingReader { +func newDecryptingReader(r io.Reader, password string, iterations int) *decryptingReader { return &decryptingReader{ r: bufio.NewReaderSize(r, 0), // we only need .UnreadByte decrypter: segmentEncrypter{ - hashMetadata: *passwordMetadata, - encryptionMetadata: *e, - password: password, + password: password, + iterations: iterations, }, } } @@ -224,7 +195,7 @@ func (r *decryptingReader) initialize() error { if r.initialized { return nil } - header := make([]byte, r.decrypter.hashMetadata.SaltSize) + header := make([]byte, saltSize) if _, err := io.ReadFull(r.r, header); err != nil { if err == io.EOF { return io.ErrUnexpectedEOF @@ -234,7 +205,7 @@ func (r *decryptingReader) initialize() error { if err := r.decrypter.initialize(header); err != nil { return err } - r.buf = *bytes.NewBuffer(make([]byte, 0, r.decrypter.encryptionMetadata.SegmentSize+1)) + r.buf = *bytes.NewBuffer(make([]byte, 0, segmentSize+1)) r.initialized = true return nil } @@ -242,17 +213,22 @@ func (r *decryptingReader) initialize() error { func (r *decryptingReader) fillBuf() error { r.buf.Reset() // Read 1 extra byte to make sure if we're at EOF. - buf := r.buf.AvailableBuffer()[:r.decrypter.encryptionMetadata.SegmentSize+1] + buf := r.buf.AvailableBuffer()[:segmentSize+1] n, err := io.ReadFull(r.r, buf) - if err != nil && err != io.ErrUnexpectedEOF { + if err == io.ErrUnexpectedEOF { + r.readFinalBlock = true + } else if err != nil { + if err == io.EOF && !r.readFinalBlock { + return errors.New("premature EOF") + } return err } buf = buf[:n] - if len(buf) == int(r.decrypter.encryptionMetadata.SegmentSize)+1 { + if len(buf) == int(segmentSize)+1 { r.r.UnreadByte() - buf = buf[:r.decrypter.encryptionMetadata.SegmentSize] + buf = buf[:segmentSize] } - buf, err = r.decrypter.decrypt(buf[:0], buf, err == io.ErrUnexpectedEOF) + buf, err = r.decrypter.decrypt(buf[:0], buf, r.readFinalBlock) if err != nil { return err } |