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108 lines
2.4 KiB
108 lines
2.4 KiB
// Copyright 2017 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 algorithm
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/des"
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"golang.org/x/crypto/cast5"
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)
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// Cipher is an official symmetric key cipher algorithm. See RFC 4880,
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// section 9.2.
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type Cipher interface {
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// Id returns the algorithm ID, as a byte, of the cipher.
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Id() uint8
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// KeySize returns the key size, in bytes, of the cipher.
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KeySize() int
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// BlockSize returns the block size, in bytes, of the cipher.
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BlockSize() int
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// New returns a fresh instance of the given cipher.
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New(key []byte) cipher.Block
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}
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// The following constants mirror the OpenPGP standard (RFC 4880).
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const (
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TripleDES = CipherFunction(2)
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CAST5 = CipherFunction(3)
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AES128 = CipherFunction(7)
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AES192 = CipherFunction(8)
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AES256 = CipherFunction(9)
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)
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// CipherById represents the different block ciphers specified for OpenPGP. See
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// http://www.iana.org/assignments/pgp-parameters/pgp-parameters.xhtml#pgp-parameters-13
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var CipherById = map[uint8]Cipher{
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TripleDES.Id(): TripleDES,
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CAST5.Id(): CAST5,
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AES128.Id(): AES128,
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AES192.Id(): AES192,
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AES256.Id(): AES256,
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}
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type CipherFunction uint8
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// ID returns the algorithm Id, as a byte, of cipher.
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func (sk CipherFunction) Id() uint8 {
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return uint8(sk)
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}
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var keySizeByID = map[uint8]int{
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TripleDES.Id(): 24,
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CAST5.Id(): cast5.KeySize,
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AES128.Id(): 16,
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AES192.Id(): 24,
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AES256.Id(): 32,
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}
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// KeySize returns the key size, in bytes, of cipher.
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func (cipher CipherFunction) KeySize() int {
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switch cipher {
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case TripleDES:
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return 24
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case CAST5:
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return cast5.KeySize
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case AES128:
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return 16
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case AES192:
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return 24
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case AES256:
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return 32
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}
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return 0
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}
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// BlockSize returns the block size, in bytes, of cipher.
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func (cipher CipherFunction) BlockSize() int {
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switch cipher {
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case TripleDES:
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return des.BlockSize
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case CAST5:
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return 8
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case AES128, AES192, AES256:
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return 16
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}
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return 0
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}
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// New returns a fresh instance of the given cipher.
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func (cipher CipherFunction) New(key []byte) (block cipher.Block) {
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var err error
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switch cipher {
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case TripleDES:
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block, err = des.NewTripleDESCipher(key)
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case CAST5:
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block, err = cast5.NewCipher(key)
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case AES128, AES192, AES256:
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block, err = aes.NewCipher(key)
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}
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if err != nil {
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panic(err.Error())
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}
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return
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}
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