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66 lines
1.2 KiB
66 lines
1.2 KiB
// Copyright (C) 2019 ProtonTech AG
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package algorithm
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import (
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"crypto/cipher"
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"github.com/ProtonMail/go-crypto/eax"
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"github.com/ProtonMail/go-crypto/ocb"
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)
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// AEADMode defines the Authenticated Encryption with Associated Data mode of
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// operation.
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type AEADMode uint8
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// Supported modes of operation (see RFC4880bis [EAX] and RFC7253)
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const (
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AEADModeEAX = AEADMode(1)
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AEADModeOCB = AEADMode(2)
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AEADModeGCM = AEADMode(100)
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)
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// TagLength returns the length in bytes of authentication tags.
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func (mode AEADMode) TagLength() int {
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switch mode {
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case AEADModeEAX:
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return 16
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case AEADModeOCB:
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return 16
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case AEADModeGCM:
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return 16
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default:
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return 0
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}
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}
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// NonceLength returns the length in bytes of nonces.
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func (mode AEADMode) NonceLength() int {
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switch mode {
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case AEADModeEAX:
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return 16
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case AEADModeOCB:
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return 15
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case AEADModeGCM:
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return 12
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default:
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return 0
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}
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}
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// New returns a fresh instance of the given mode
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func (mode AEADMode) New(block cipher.Block) (alg cipher.AEAD) {
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var err error
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switch mode {
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case AEADModeEAX:
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alg, err = eax.NewEAX(block)
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case AEADModeOCB:
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alg, err = ocb.NewOCB(block)
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case AEADModeGCM:
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alg, err = cipher.NewGCM(block)
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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 alg
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}
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