mirror of https://github.com/cheat/cheat.git
91 lines
2.7 KiB
Go
91 lines
2.7 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package packet
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import (
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"io"
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"github.com/ProtonMail/go-crypto/openpgp/errors"
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)
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const aeadSaltSize = 32
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// SymmetricallyEncrypted represents a symmetrically encrypted byte string. The
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// encrypted Contents will consist of more OpenPGP packets. See RFC 4880,
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// sections 5.7 and 5.13.
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type SymmetricallyEncrypted struct {
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Version int
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Contents io.Reader // contains tag for version 2
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IntegrityProtected bool // If true it is type 18 (with MDC or AEAD). False is packet type 9
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// Specific to version 1
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prefix []byte
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// Specific to version 2
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Cipher CipherFunction
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Mode AEADMode
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ChunkSizeByte byte
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Salt [aeadSaltSize]byte
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}
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const (
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symmetricallyEncryptedVersionMdc = 1
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symmetricallyEncryptedVersionAead = 2
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)
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func (se *SymmetricallyEncrypted) parse(r io.Reader) error {
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if se.IntegrityProtected {
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// See RFC 4880, section 5.13.
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var buf [1]byte
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_, err := readFull(r, buf[:])
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if err != nil {
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return err
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}
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switch buf[0] {
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case symmetricallyEncryptedVersionMdc:
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se.Version = symmetricallyEncryptedVersionMdc
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case symmetricallyEncryptedVersionAead:
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se.Version = symmetricallyEncryptedVersionAead
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if err := se.parseAead(r); err != nil {
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return err
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}
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default:
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return errors.UnsupportedError("unknown SymmetricallyEncrypted version")
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}
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}
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se.Contents = r
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return nil
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}
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// Decrypt returns a ReadCloser, from which the decrypted Contents of the
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// packet can be read. An incorrect key will only be detected after trying
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// to decrypt the entire data.
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func (se *SymmetricallyEncrypted) Decrypt(c CipherFunction, key []byte) (io.ReadCloser, error) {
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if se.Version == symmetricallyEncryptedVersionAead {
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return se.decryptAead(key)
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}
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return se.decryptMdc(c, key)
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}
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// SerializeSymmetricallyEncrypted serializes a symmetrically encrypted packet
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// to w and returns a WriteCloser to which the to-be-encrypted packets can be
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// written.
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// If config is nil, sensible defaults will be used.
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func SerializeSymmetricallyEncrypted(w io.Writer, c CipherFunction, aeadSupported bool, cipherSuite CipherSuite, key []byte, config *Config) (Contents io.WriteCloser, err error) {
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writeCloser := noOpCloser{w}
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ciphertext, err := serializeStreamHeader(writeCloser, packetTypeSymmetricallyEncryptedIntegrityProtected)
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if err != nil {
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return
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}
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if aeadSupported {
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return serializeSymmetricallyEncryptedAead(ciphertext, cipherSuite, config.AEADConfig.ChunkSizeByte(), config.Random(), key)
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}
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return serializeSymmetricallyEncryptedMdc(ciphertext, c, key, config)
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}
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