86 lines
2.7 KiB
TypeScript
86 lines
2.7 KiB
TypeScript
// Copyright 2021 MengYX. All rights reserved.
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//
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// Copyright 2015 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 https://go.dev/LICENSE.
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// TeaCipher is a typescript port to golang.org/x/crypto/tea
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// Package tea implements the TEA algorithm, as defined in Needham and
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// Wheeler's 1994 technical report, “TEA, a Tiny Encryption Algorithm”. See
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// http://www.cix.co.uk/~klockstone/tea.pdf for details.
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//
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// TEA is a legacy cipher and its short block size makes it vulnerable to
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// birthday bound attacks (see https://sweet32.info). It should only be used
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// where compatibility with legacy systems, not security, is the goal.
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export class TeaCipher {
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// BlockSize is the size of a TEA block, in bytes.
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static readonly BlockSize = 8;
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// KeySize is the size of a TEA key, in bytes.
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static readonly KeySize = 16;
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// delta is the TEA key schedule constant.
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static readonly delta = 0x9e3779b9;
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// numRounds 64 is the standard number of rounds in TEA.
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static readonly numRounds = 64;
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k0: number
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k1: number
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k2: number
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k3: number
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rounds: number
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constructor(key: Uint8Array, rounds: number = TeaCipher.numRounds) {
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if (key.length != 16) {
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throw Error("incorrect key size")
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}
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if ((rounds & 1) != 0) {
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throw Error("odd number of rounds specified")
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}
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const k = new DataView(key.buffer)
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this.k0 = k.getUint32(0, false)
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this.k1 = k.getUint32(4, false)
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this.k2 = k.getUint32(8, false)
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this.k3 = k.getUint32(12, false)
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this.rounds = rounds
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}
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encrypt(dst: DataView, src: DataView) {
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if (src.byteLength != 8) {
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throw Error("src.byteLength != 8")
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}
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let v0 = src.getUint32(0, false)
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let v1 = src.getUint32(4, false)
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let sum = 0
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for (let i = 0; i < this.rounds / 2; i++) {
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sum = sum + TeaCipher.delta
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v0 += ((v1 << 4) + this.k0) ^ (v1 + sum) ^ ((v1 >>> 5) + this.k1)
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v1 += ((v0 << 4) + this.k2) ^ (v0 + sum) ^ ((v0 >>> 5) + this.k3)
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}
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dst.setUint32(0, v0, false)
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dst.setUint32(4, v1, false)
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}
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decrypt(dst: DataView, src: DataView) {
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let v0 = src.getUint32(0, false)
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let v1 = src.getUint32(4, false)
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let sum = TeaCipher.delta * this.rounds / 2
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for (let i = 0; i < this.rounds / 2; i++) {
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v1 -= ((v0 << 4) + this.k2) ^ (v0 + sum) ^ ((v0 >>> 5) + this.k3)
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v0 -= ((v1 << 4) + this.k0) ^ (v1 + sum) ^ ((v1 >>> 5) + this.k1)
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sum -= TeaCipher.delta
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}
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dst.setUint32(0, v0, false)
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dst.setUint32(4, v1, false)
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}
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}
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