From 9fe490ee38d8b98275c11078e56590e5fd6cf86f Mon Sep 17 00:00:00 2001 From: Adam Langley Date: Thu, 10 Feb 2011 07:56:30 -0500 Subject: [PATCH] crypto/openpgp/packet: four more packet types. R=bradfitzgo CC=golang-dev https://golang.org/cl/4156044 --- src/pkg/crypto/openpgp/packet/literal.go | 53 +++++ .../openpgp/packet/one_pass_signature.go | 49 +++++ .../openpgp/packet/symmetric_key_encrypted.go | 102 +++++++++ .../packet/symmetric_key_encrypted_test.go | 62 ++++++ .../openpgp/packet/symmetrically_encrypted.go | 206 ++++++++++++++++++ .../packet/symmetrically_encrypted_test.go | 78 +++++++ 6 files changed, 550 insertions(+) create mode 100644 src/pkg/crypto/openpgp/packet/literal.go create mode 100644 src/pkg/crypto/openpgp/packet/one_pass_signature.go create mode 100644 src/pkg/crypto/openpgp/packet/symmetric_key_encrypted.go create mode 100644 src/pkg/crypto/openpgp/packet/symmetric_key_encrypted_test.go create mode 100644 src/pkg/crypto/openpgp/packet/symmetrically_encrypted.go create mode 100644 src/pkg/crypto/openpgp/packet/symmetrically_encrypted_test.go diff --git a/src/pkg/crypto/openpgp/packet/literal.go b/src/pkg/crypto/openpgp/packet/literal.go new file mode 100644 index 0000000000..5f72d6a2cd --- /dev/null +++ b/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 +} diff --git a/src/pkg/crypto/openpgp/packet/one_pass_signature.go b/src/pkg/crypto/openpgp/packet/one_pass_signature.go new file mode 100644 index 0000000000..acbf58bbef --- /dev/null +++ b/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 +} diff --git a/src/pkg/crypto/openpgp/packet/symmetric_key_encrypted.go b/src/pkg/crypto/openpgp/packet/symmetric_key_encrypted.go new file mode 100644 index 0000000000..d9010f88a3 --- /dev/null +++ b/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 +} diff --git a/src/pkg/crypto/openpgp/packet/symmetric_key_encrypted_test.go b/src/pkg/crypto/openpgp/packet/symmetric_key_encrypted_test.go new file mode 100644 index 0000000000..717c8ffa6d --- /dev/null +++ b/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" diff --git a/src/pkg/crypto/openpgp/packet/symmetrically_encrypted.go b/src/pkg/crypto/openpgp/packet/symmetrically_encrypted.go new file mode 100644 index 0000000000..fc19ffe809 --- /dev/null +++ b/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 +} diff --git a/src/pkg/crypto/openpgp/packet/symmetrically_encrypted_test.go b/src/pkg/crypto/openpgp/packet/symmetrically_encrypted_test.go new file mode 100644 index 0000000000..ee5a30d321 --- /dev/null +++ b/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"