doubleTransposition.ts

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import { BaseCipher } from "../base/baseCipher";
import { ColumnarCipher } from "./columnar";
 
export class DoubleTranspositionCipher extends BaseCipher {
    readonly CipherName = "DoubleTransposition";
 
    constructor() {
        super();
    }
 
    encode(plainText: string = "", key1: string = "", key2?: string): string {
        const firstKey = key1;
        const secondKey = key2 ?? key1;
 
        const columnar1 = new ColumnarCipher();
        const columnar2 = new ColumnarCipher();
 
        const firstPass = columnar1.encode(plainText, firstKey);
        const secondPass = columnar2.encode(firstPass, secondKey);
 
        return secondPass;
    }
 
    decode(cipherText: string = "", key1: string = "", key2?: string): string {
        const firstKey = key1;
        const secondKey = key2 ?? key1;
 
        const columnar1 = new ColumnarCipher();
        const columnar2 = new ColumnarCipher();
 
        const intermediate = columnar2.decode(cipherText, secondKey);
        const finalText = columnar1.decode(intermediate, firstKey);
 
        return finalText;
    }
}