crypto/openpgp/packet: four more packet types.

R=bradfitzgo
CC=golang-dev
https://golang.org/cl/4156044

src/pkg/crypto/openpgp/packet/literal.go

@@ -0,0 +1,53 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"encoding/binary"
+	"io"
+	"os"
+)
+
+// LiteralData represents an encrypted file. See RFC 4880, section 5.9.
+type LiteralData struct {
+	IsBinary bool
+	FileName string
+	Time     uint32 // Unix epoc time. Either creation time or modification time. 0 means undefined.
+	Body     io.Reader
+}
+
+// ForEyesOnly return whether the contents of the LiteralData have been marked
+// as especially sensitive.
+func (l *LiteralData) ForEyesOnly() bool {
+	return l.FileName == "_CONSOLE"
+}
+
+func (l *LiteralData) parse(r io.Reader) (err os.Error) {
+	var buf [256]byte
+
+	_, err = readFull(r, buf[:2])
+	if err != nil {
+		return
+	}
+
+	l.IsBinary = buf[0] == 'b'
+	fileNameLen := int(buf[1])
+
+	_, err = readFull(r, buf[:fileNameLen])
+	if err != nil {
+		return
+	}
+
+	l.FileName = string(buf[:fileNameLen])
+
+	_, err = readFull(r, buf[:4])
+	if err != nil {
+		return
+	}
+
+	l.Time = binary.BigEndian.Uint32(buf[:4])
+	l.Body = r
+	return
+}

src/pkg/crypto/openpgp/packet/one_pass_signature.go

@@ -0,0 +1,49 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"crypto"
+	"crypto/openpgp/error"
+	"crypto/openpgp/s2k"
+	"encoding/binary"
+	"io"
+	"os"
+	"strconv"
+)
+
+// OnePassSignature represents a one-pass signature packet. See RFC 4880,
+// section 5.4.
+type OnePassSignature struct {
+	SigType    SignatureType
+	Hash       crypto.Hash
+	PubKeyAlgo PublicKeyAlgorithm
+	KeyId      uint64
+	IsLast     bool
+}
+
+func (ops *OnePassSignature) parse(r io.Reader) (err os.Error) {
+	var buf [13]byte
+
+	_, err = readFull(r, buf[:])
+	if err != nil {
+		return
+	}
+	if buf[0] != 3 {
+		err = error.UnsupportedError("one-pass-signature packet version " + strconv.Itoa(int(buf[0])))
+	}
+
+	var ok bool
+	ops.Hash, ok = s2k.HashIdToHash(buf[2])
+	if !ok {
+		return error.UnsupportedError("hash function: " + strconv.Itoa(int(buf[2])))
+	}
+
+	ops.SigType = SignatureType(buf[1])
+	ops.PubKeyAlgo = PublicKeyAlgorithm(buf[3])
+	ops.KeyId = binary.BigEndian.Uint64(buf[4:12])
+	ops.IsLast = buf[12] != 0
+	return
+}

src/pkg/crypto/openpgp/packet/symmetric_key_encrypted.go

@@ -0,0 +1,102 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"crypto/cipher"
+	"crypto/openpgp/error"
+	"crypto/openpgp/s2k"
+	"io"
+	"os"
+	"strconv"
+)
+
+// This is the largest session key that we'll support. Since no 512-bit cipher
+// has even been seriously used, this is comfortably large.
+const maxSessionKeySizeInBytes = 64
+
+// SymmetricKeyEncrypted represents a passphrase protected session key. See RFC
+// 4880, section 5.3.
+type SymmetricKeyEncrypted struct {
+	CipherFunc   CipherFunction
+	Encrypted    bool
+	Key          []byte // Empty unless Encrypted is false.
+	s2k          func(out, in []byte)
+	encryptedKey []byte
+}
+
+func (ske *SymmetricKeyEncrypted) parse(r io.Reader) (err os.Error) {
+	// RFC 4880, section 5.3.
+	var buf [2]byte
+	_, err = readFull(r, buf[:])
+	if err != nil {
+		return
+	}
+	if buf[0] != 4 {
+		return error.UnsupportedError("SymmetricKeyEncrypted version")
+	}
+	ske.CipherFunc = CipherFunction(buf[1])
+
+	if ske.CipherFunc.keySize() == 0 {
+		return error.UnsupportedError("unknown cipher: " + strconv.Itoa(int(buf[1])))
+	}
+
+	ske.s2k, err = s2k.Parse(r)
+	if err != nil {
+		return
+	}
+
+	encryptedKey := make([]byte, maxSessionKeySizeInBytes)
+	// The session key may follow. We just have to try and read to find
+	// out. If it exists then we limit it to maxSessionKeySizeInBytes.
+	n, err := readFull(r, encryptedKey)
+	if err != nil && err != io.ErrUnexpectedEOF {
+		return
+	}
+	err = nil
+	if n != 0 {
+		if n == maxSessionKeySizeInBytes {
+			return error.UnsupportedError("oversized encrypted session key")
+		}
+		ske.encryptedKey = encryptedKey[:n]
+	}
+
+	ske.Encrypted = true
+
+	return
+}
+
+// Decrypt attempts to decrypt an encrypted session key. If it returns nil,
+// ske.Key will contain the session key.
+func (ske *SymmetricKeyEncrypted) Decrypt(passphrase []byte) os.Error {
+	if !ske.Encrypted {
+		return nil
+	}
+
+	key := make([]byte, ske.CipherFunc.keySize())
+	ske.s2k(key, passphrase)
+
+	if len(ske.encryptedKey) == 0 {
+		ske.Key = key
+	} else {
+		// the IV is all zeros
+		iv := make([]byte, ske.CipherFunc.blockSize())
+		c := cipher.NewCFBDecrypter(ske.CipherFunc.new(key), iv)
+		c.XORKeyStream(ske.encryptedKey, ske.encryptedKey)
+		ske.CipherFunc = CipherFunction(ske.encryptedKey[0])
+		if ske.CipherFunc.blockSize() == 0 {
+			return error.UnsupportedError("unknown cipher: " + strconv.Itoa(int(ske.CipherFunc)))
+		}
+		ske.CipherFunc = CipherFunction(ske.encryptedKey[0])
+		ske.Key = ske.encryptedKey[1:]
+		if len(ske.Key)%ske.CipherFunc.blockSize() != 0 {
+			ske.Key = nil
+			return error.StructuralError("length of decrypted key not a multiple of block size")
+		}
+	}
+
+	ske.Encrypted = false
+	return nil
+}

src/pkg/crypto/openpgp/packet/symmetric_key_encrypted_test.go

@@ -0,0 +1,62 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"bytes"
+	"encoding/hex"
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+func TestSymmetricKeyEncrypted(t *testing.T) {
+	buf := readerFromHex(symmetricallyEncryptedHex)
+	packet, err := Read(buf)
+	if err != nil {
+		t.Errorf("failed to read SymmetricKeyEncrypted: %s", err)
+		return
+	}
+	ske, ok := packet.(*SymmetricKeyEncrypted)
+	if !ok {
+		t.Error("didn't find SymmetricKeyEncrypted packet")
+		return
+	}
+	err = ske.Decrypt([]byte("password"))
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	packet, err = Read(buf)
+	if err != nil {
+		t.Errorf("failed to read SymmetricallyEncrypted: %s", err)
+		return
+	}
+	se, ok := packet.(*SymmetricallyEncrypted)
+	if !ok {
+		t.Error("didn't find SymmetricallyEncrypted packet")
+		return
+	}
+	r, err := se.Decrypt(ske.CipherFunc, ske.Key)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	contents, err := ioutil.ReadAll(r)
+	if err != nil && err != os.EOF {
+		t.Error(err)
+		return
+	}
+
+	expectedContents, _ := hex.DecodeString(symmetricallyEncryptedContentsHex)
+	if !bytes.Equal(expectedContents, contents) {
+		t.Errorf("bad contents got:%x want:%x", contents, expectedContents)
+	}
+}
+
+const symmetricallyEncryptedHex = "8c0d04030302371a0b38d884f02060c91cf97c9973b8e58e028e9501708ccfe618fb92afef7fa2d80ddadd93cf"
+const symmetricallyEncryptedContentsHex = "cb1062004d14c4df636f6e74656e74732e0a"

src/pkg/crypto/openpgp/packet/symmetrically_encrypted.go

@@ -0,0 +1,206 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"crypto/cipher"
+	"crypto/openpgp/error"
+	"crypto/sha1"
+	"crypto/subtle"
+	"hash"
+	"io"
+	"os"
+	"strconv"
+)
+
+// SymmetricallyEncrypted represents a symmetrically encrypted byte string. The
+// encrypted contents will consist of more OpenPGP packets. See RFC 4880,
+// sections 5.7 and 5.13.
+type SymmetricallyEncrypted struct {
+	MDC      bool // true iff this is a type 18 packet and thus has an embedded MAC.
+	contents io.Reader
+	prefix   []byte
+}
+
+func (se *SymmetricallyEncrypted) parse(r io.Reader) os.Error {
+	if se.MDC {
+		// See RFC 4880, section 5.13.
+		var buf [1]byte
+		_, err := readFull(r, buf[:])
+		if err != nil {
+			return err
+		}
+		if buf[0] != 1 {
+			return error.UnsupportedError("unknown SymmetricallyEncrypted version")
+		}
+	}
+	se.contents = r
+	return nil
+}
+
+// Decrypt returns a ReadCloser, from which the decrypted contents of the
+// packet can be read. An incorrect key can, with high probability, be detected
+// immediately and this will result in a KeyIncorrect error being returned.
+func (se *SymmetricallyEncrypted) Decrypt(c CipherFunction, key []byte) (io.ReadCloser, os.Error) {
+	keySize := c.keySize()
+	if keySize == 0 {
+		return nil, error.UnsupportedError("unknown cipher: " + strconv.Itoa(int(c)))
+	}
+	if len(key) != keySize {
+		return nil, error.InvalidArgumentError("SymmetricallyEncrypted: incorrect key length")
+	}
+
+	if se.prefix == nil {
+		se.prefix = make([]byte, c.blockSize()+2)
+		_, err := readFull(se.contents, se.prefix)
+		if err != nil {
+			return nil, err
+		}
+	} else if len(se.prefix) != c.blockSize()+2 {
+		return nil, error.InvalidArgumentError("can't try ciphers with different block lengths")
+	}
+
+	ocfbResync := cipher.OCFBResync
+	if se.MDC {
+		// MDC packets use a different form of OCFB mode.
+		ocfbResync = cipher.OCFBNoResync
+	}
+
+	s := cipher.NewOCFBDecrypter(c.new(key), se.prefix, ocfbResync)
+	if s == nil {
+		return nil, error.KeyIncorrectError
+	}
+
+	plaintext := cipher.StreamReader{S: s, R: se.contents}
+
+	if se.MDC {
+		// MDC packets have an embedded hash that we need to check.
+		h := sha1.New()
+		h.Write(se.prefix)
+		return &seMDCReader{in: plaintext, h: h}, nil
+	}
+
+	// Otherwise, we just need to wrap plaintext so that it's a valid ReadCloser.
+	return seReader{plaintext}, nil
+}
+
+// seReader wraps an io.Reader with a no-op Close method.
+type seReader struct {
+	in io.Reader
+}
+
+func (ser seReader) Read(buf []byte) (int, os.Error) {
+	return ser.in.Read(buf)
+}
+
+func (ser seReader) Close() os.Error {
+	return nil
+}
+
+const mdcTrailerSize = 1 /* tag byte */ + 1 /* length byte */ + sha1.Size
+
+// An seMDCReader wraps an io.Reader, maintains a running hash and keeps hold
+// of the most recent 22 bytes (mdcTrailerSize). Upon EOF, those bytes form an
+// MDC packet containing a hash of the previous contents which is checked
+// against the running hash. See RFC 4880, section 5.13.
+type seMDCReader struct {
+	in          io.Reader
+	h           hash.Hash
+	trailer     [mdcTrailerSize]byte
+	scratch     [mdcTrailerSize]byte
+	trailerUsed int
+	error       bool
+	eof         bool
+}
+
+func (ser *seMDCReader) Read(buf []byte) (n int, err os.Error) {
+	if ser.error {
+		err = io.ErrUnexpectedEOF
+		return
+	}
+	if ser.eof {
+		err = os.EOF
+		return
+	}
+
+	// If we haven't yet filled the trailer buffer then we must do that
+	// first.
+	for ser.trailerUsed < mdcTrailerSize {
+		n, err = ser.in.Read(ser.trailer[ser.trailerUsed:])
+		ser.trailerUsed += n
+		if err == os.EOF {
+			if ser.trailerUsed != mdcTrailerSize {
+				n = 0
+				err = io.ErrUnexpectedEOF
+				ser.error = true
+				return
+			}
+			ser.eof = true
+			n = 0
+			return
+		}
+
+		if err != nil {
+			n = 0
+			return
+		}
+	}
+
+	// If it's a short read then we read into a temporary buffer and shift
+	// the data into the caller's buffer.
+	if len(buf) <= mdcTrailerSize {
+		n, err = readFull(ser.in, ser.scratch[:len(buf)])
+		copy(buf, ser.trailer[:n])
+		ser.h.Write(buf[:n])
+		copy(ser.trailer[:], ser.trailer[n:])
+		copy(ser.trailer[mdcTrailerSize-n:], ser.scratch[:])
+		if n < len(buf) {
+			ser.eof = true
+			err = os.EOF
+		}
+		return
+	}
+
+	n, err = ser.in.Read(buf[mdcTrailerSize:])
+	copy(buf, ser.trailer[:])
+	ser.h.Write(buf[:n])
+	copy(ser.trailer[:], buf[n:])
+
+	if err == os.EOF {
+		ser.eof = true
+	}
+	return
+}
+
+func (ser *seMDCReader) Close() os.Error {
+	if ser.error {
+		return error.SignatureError("error during reading")
+	}
+
+	for !ser.eof {
+		// We haven't seen EOF so we need to read to the end
+		var buf [1024]byte
+		_, err := ser.Read(buf[:])
+		if err == os.EOF {
+			break
+		}
+		if err != nil {
+			return error.SignatureError("error during reading")
+		}
+	}
+
+	// This is a new-format packet tag byte for a type 19 (MDC) packet.
+	const mdcPacketTagByte = byte(0x80) | 0x40 | 19
+	if ser.trailer[0] != mdcPacketTagByte || ser.trailer[1] != sha1.Size {
+		return error.SignatureError("MDC packet not found")
+	}
+	ser.h.Write(ser.trailer[:2])
+
+	final := ser.h.Sum()
+	if subtle.ConstantTimeCompare(final, ser.trailer[2:]) == 1 {
+		return error.SignatureError("hash mismatch")
+	}
+	return nil
+}

src/pkg/crypto/openpgp/packet/symmetrically_encrypted_test.go

@@ -0,0 +1,78 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"bytes"
+	"crypto/openpgp/error"
+	"crypto/sha1"
+	"encoding/hex"
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+// TestReader wraps a []byte and returns reads of a specific length.
+type testReader struct {
+	data   []byte
+	stride int
+}
+
+func (t *testReader) Read(buf []byte) (n int, err os.Error) {
+	n = t.stride
+	if n > len(t.data) {
+		n = len(t.data)
+	}
+	if n > len(buf) {
+		n = len(buf)
+	}
+	copy(buf, t.data)
+	t.data = t.data[n:]
+	if len(t.data) == 0 {
+		err = os.EOF
+	}
+	return
+}
+
+func testMDCReader(t *testing.T) {
+	mdcPlaintext, _ := hex.DecodeString(mdcPlaintextHex)
+
+	for stride := 1; stride < len(mdcPlaintext)/2; stride++ {
+		r := &testReader{data: mdcPlaintext, stride: stride}
+		mdcReader := &seMDCReader{in: r, h: sha1.New()}
+		body, err := ioutil.ReadAll(mdcReader)
+		if err != nil {
+			t.Errorf("stride: %d, error: %s", stride, err)
+			continue
+		}
+		if !bytes.Equal(body, mdcPlaintext[:len(mdcPlaintext)-22]) {
+			t.Errorf("stride: %d: bad contents %x", stride, body)
+			continue
+		}
+
+		err = mdcReader.Close()
+		if err != nil {
+			t.Errorf("stride: %d, error on Close: %s", err)
+		}
+	}
+
+	mdcPlaintext[15] ^= 80
+
+	r := &testReader{data: mdcPlaintext, stride: 2}
+	mdcReader := &seMDCReader{in: r, h: sha1.New()}
+	_, err := ioutil.ReadAll(mdcReader)
+	if err != nil {
+		t.Errorf("corruption test, error: %s", err)
+		return
+	}
+	err = mdcReader.Close()
+	if err == nil {
+		t.Error("corruption: no error")
+	} else if _, ok := err.(*error.SignatureError); !ok {
+		t.Errorf("corruption: expected SignatureError, got: %s", err)
+	}
+}
+
+const mdcPlaintextHex = "a302789c3b2d93c4e0eb9aba22283539b3203335af44a134afb800c849cb4c4de10200aff40b45d31432c80cb384299a0655966d6939dfdeed1dddf980"