RC4.java

package com.xiaomi.smarthome.library.crypto.rc4coder;

final class RC4 {
    private int a;
    private int b;
    private final byte[] c = new byte[256];

    public RC4(byte[] bArr) {
        int i;
        int length = bArr.length;
        for (i = 0; i < 256; i++) {
            this.c[i] = (byte) i;
        }
        i = 0;
        for (int i2 = 0; i2 < 256; i2++) {
            i = ((i + bArr[i2 % length]) + this.c[i2]) & 255;
            byte b = this.c[i2];
            this.c[i2] = this.c[i];
            this.c[i] = b;
        }
        this.a = 0;
        this.b = 0;
    }

    public byte a() {
        this.a = (this.a + 1) & 255;
        this.b = (this.b + this.c[this.a]) & 255;
        byte b = this.c[this.a];
        this.c[this.a] = this.c[this.b];
        this.c[this.b] = b;
        return this.c[(this.c[this.a] + this.c[this.b]) & 255];
    }

    public void a(byte[] bArr) {
        for (int i = 0; i < bArr.length; i++) {
            bArr[i] = (byte) (bArr[i] ^ a());
        }
    }
}