KeeLoq算法的核心思想就是用8byte密鑰加密4byte明文，從而得到4byte密文或者用8byte密鑰解密4byte密文，還原出原4byte明文。KeeLoq算法演算過程需要定義一個(gè)數(shù)據(jù)寄存器，用于存放4byte明文y31-y0或者4byte密文y31-y0，和一個(gè)密鑰寄存器，用于存放8byte密鑰k63-k0。其加密特點(diǎn)是運(yùn)算速度快，加密性高，線性等。

var NLF = [
    [
        [
            [
                [
                    [],
                    []
                ],
                [
                    [],
                    []
                ]
            ],
            [
                [
                    [],
                    []
                ],
                [
                    [],
                    []
                ]
            ]
        ],
        [
            [
                [
                    [],
                    []
                ],
                [
                    [],
                    []
                ]
            ],
            [
                [
                    [],
                    []
                ],
                [
                    [],
                    []
                ]
            ]
        ]
    ],
    [
        [
            [
                [
                    [],
                    []
                ],
                [
                    [],
                    []
                ]
            ],
            [
                [
                    [],
                    []
                ],
                [
                    [],
                    []
                ]
            ]
        ],
        [
            [
                [
                    [],
                    []
                ],
                [
                    [],
                    []
                ]
            ],
            [
                [
                    [],
                    []
                ],
                [
                    [],
                    []
                ]
            ]
        ]
    ]
]


NLF[0][0][0][0][0]=0;
NLF[0][0][0][0][1]=1;
NLF[0][0][0][1][0]=1;
NLF[0][0][0][1][1]=1;
NLF[0][0][1][0][0]=0;
NLF[0][0][1][0][1]=1;
NLF[0][0][1][1][0]=0;
NLF[0][0][1][1][1]=0;

NLF[0][1][0][0][0]=0;
NLF[0][1][0][0][1]=0;
NLF[0][1][0][1][0]=1;
NLF[0][1][0][1][1]=0;
NLF[0][1][1][0][0]=1;
NLF[0][1][1][0][1]=1;
NLF[0][1][1][1][0]=1;
NLF[0][1][1][1][1]=0;

NLF[1][0][0][0][0]=0;
NLF[1][0][0][0][1]=0;
NLF[1][0][0][1][0]=1;
NLF[1][0][0][1][1]=1;
NLF[1][0][1][0][0]=1;
NLF[1][0][1][0][1]=0;
NLF[1][0][1][1][0]=1;
NLF[1][0][1][1][1]=0;

NLF[1][1][0][0][0]=0;
NLF[1][1][0][0][1]=1;
NLF[1][1][0][1][0]=0;
NLF[1][1][0][1][1]=1;
NLF[1][1][1][0][0]=1;
NLF[1][1][1][0][1]=1;
NLF[1][1][1][1][0]=0;
NLF[1][1][1][1][1]=0;


//獲取source第n個(gè)位數(shù)
function getBit(source,n) {
    var temp0 = 1 << n;
    var temp1 = source & temp0;
    if (temp1 != 0){
        return 1;
    }
    return 0;
}

//source帶進(jìn)位右移
function RRC(source,c) {
    if (c != 0){
        source = (source >> 1) | 0x80000000;
    }else {
        source = (source >> 1) & 0x7fffffff;
    }
    return source;
}

//source帶進(jìn)位左移
function RLC(source,c) {
    if (c != 0){
        source = (source << 1) | 0x01;
    }else {
        source = (source << 1) & 0xFFFFFFFE;
    }
    return source;
}


/*
    source進(jìn)行加密
    用8byte的key做密鑰進(jìn)行加密，js中l(wèi)ong類型會(huì)精度丟失，所以把8byte的key分成低四位和高四位。
 */
function CRYPT(source,lkey,hkey) {
    var c;
    for (var i = 0;i < 528;i ++){
        var nlf = NLF[getBit(source, 31)][getBit(source, 26)][getBit(source, 20)][getBit(source, 9)][getBit(source,
            1)];
        var y16 = getBit(source, 16);
        var y0 = getBit(source, 0);
        var index = i % 64;
        var k;
        if (index < 32){
            k = getBit(lkey,index);
        }else {
            k = getBit(hkey, index);
        }
        var result = nlf ^ y16 ^ y0 ^ k;
        if (result != 0) {
            c = 1;
        } else {
            c = 0;
        }
        source = RRC(source, c);
    }

    return source;
}

/*
    source進(jìn)行解密
    用8byte的key做密鑰進(jìn)行加密，js中l(wèi)ong類型會(huì)精度丟失，所以把8byte的key分成低四位和高四位。
 */
function DECRYPT(source,lkey,hkey) {
    var c;
    for (var i = 528;i > 0; i--){
        var nlf = NLF[getBit(source, 30)][getBit(source, 25)][getBit(source, 19)][getBit(source, 8)][getBit(source,
            0)];
        var y15 = getBit(source, 15);
        var y31 = getBit(source, 31);
        var index = (i-1) % 64;
        var k;
        if (index < 32){
            k = getBit(lkey,index);
        }else {
            k = getBit(hkey, index);
        }
        var result = nlf ^ y15 ^ y31 ^ k;
        if (result != 0) {
            c = 1;
        } else {
            c = 0;
        }
        source = RLC(source, c);
    }

    return source;
}

使用:

window.onload = function () {

        //key低四位
        var lkey = 0x43658709;
        //key高四位
        var hkey = 0xefcdab21;
        var source = 1520149488;
        var crypt = CRYPT(source,lkey,hkey);
        console.log("加密前數(shù)據(jù)：" + source);
        console.log("加密后數(shù)據(jù)：" + crypt);
        console.log("解密后數(shù)據(jù):" + DECRYPT(crypt,lkey,hkey));

    }

控制臺(tái)輸出

屏幕快照 2018-04-04 10.34.32.png

附：
Keeloq算法 - c語言實(shí)現(xiàn)
Keeloq算法 - java語言實(shí)現(xiàn)