Ikhowudi kwiinombolo eziphambili04
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Ngo-Okthobha ka-1999, iqela elalikhokelwa nguJon Lech Johansen waseNorway owayeneminyaka eli-16 ubudala ngelo xesha lakhupha inkqubo yeDeCSS ukuze liphephe ukhuseleko lokudlala iDVD kwiContent Scramble System (CSS). I-CSS yasebenzisa i-40-bit encryption, izitshixo ezazisasazwa kubavelisi abaneelayisenisi, ukuze kuthintelwe ukudlala iDVD. Ngenxa yokuba ukusasazwa kwekhowudi kwawela phantsi kwe-US DMCA kwaye kwakungavumelekanga ngokusemthethweni, abaxhasi bafuna iindlela zokufihla ikhowudi njengento yezibalo.

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Emva koko uPhil Carmody wakha inombolo ephambili ethi, xa itolikwa kwi-binary emva kwe-gzip decompression, iqulathe ikhowudi epheleleyo yomthombo weDeCSS. Isiseko se-algorithm yeDeCSS singasetyenziswa kwiTypeScript ngolu hlobo lulandelayo, apho imisebenzi ye-bit imaphu ngqo kwi-sector decryption logic.:

function CSSdescramble(sec: Uint8Array, key: Uint8Array): void {
    let t1: number, t2: number, t3: number, t4: number, t5: number, t6: number;
    const end = 0x800;

    t1 = (key[0] ^ sec[0x54]) | 0x100;
    t2 = key[1] ^ sec[0x55];

    const keyView = new DataView(key.buffer, key.byteOffset);
    const secView = new DataView(sec.buffer, sec.byteOffset);

    t3 = (keyView.getUint32(2, true) ^ secView.getUint32(0x56, true)) >>> 0;
    t4 = t3 & 7;
    t3 = (t3 * 2 + 8 - t4) >>> 0;

    let offset = 0x80;
    t5 = 0;

    while (offset < end) {
        t4 = CSStab2[t2] ^ CSStab3[t1];
        t2 = t1 >>> 1;
        t1 = ((t1 & 1) << 8) ^ t4;
        t4 = CSStab5[t4];
        t6 = (((((((t3 >>> 3) ^ t3) >>> 1) ^ t3) >>> 8) ^ t3) >>> 5) & 0xff;
        t3 = (((t3 << 8) >>> 0) | t6) >>> 0;
        t6 = CSStab4[t6];
        t5 += t6 + t4;

        sec[offset] = CSStab1[sec[offset]] ^ (t5 & 0xff);
        t5 >>>= 8;
        offset++;
    }
}

Umgaqo osemva kwenani eliphambili kukutolika yonke ikhowudi yomthombo njengenani elipheleleyo elinye neliqinileyo. Ekubeni kungekho fayile inikiweyo eyinani eliphambili, inani linyuswa ngokwenziwa ngee-bytes ezongezelelweyo (i-padding). Le padding inyuswa kwi-loop de uvavanyo lwe-primality, olufana novavanyo lweMiller-Rabin, luqinisekise ukuba inani liphambili. Le generator ilandelayo isebenzisa ikhowudi yeDeCSS echazwe apha ngasentla kwaye ikhangela umelo lwenani eliphambili elifanelekileyo.:

import { isPrime } from 'crypto-utils-lib'; // Hypothetical library for primality testing

async function generateIllegalPrime(code: string): Promise<bigint | null> {
    const encoder = new TextEncoder();
    const bytes = encoder.encode(code);

    let hexBase = Array.from(bytes)
        .map(b => b.toString(16).padStart(2, '0'))
        .join('');

    // Start bei 1, da 0x00 immer gerade und damit keine Primzahl ist
    for (let i = 1; i < 256; i++) {
        const candidateHex = hexBase + i.toString(16).padStart(2, '0');
        const candidateInt = BigInt('0x' + candidateHex);

        if (await isPrime(candidateInt)) {
            return candidateInt;
        }
    }
    return null;
}

const source = `void CSSdescramble(unsigned char *sec, unsigned char *key) { ... }`;
generateIllegalPrime(source).then(p => console.log(p));

Iqhinga lenani eliphambili alizange libe yinto exoxwa ngayo kwityala elahlukileyo lenkundla, kwaye kwakungafuneki ukuba libe njalo. Nangona inani eliphambili likaCarmody lalinamanani ali-1401, lalilincinci kakhulu kuluhlu oluphezulu lwamanani amakhulu e-prime ngelo xesha. Kamva wenza inguqulelo enamanani ali-1905, eyazaliswa ngokwenziwa ngee-null bytes, ukuze ifumane indawo yeshumi kuluhlu lwe-ECPP . Le mpumelelo ibonise ukungakwazi ukucutha izibalo ezicocekileyo, njengoko inani lafumana indawo yalo kuluhlu kuphela ngokusekelwe kwiimpawu zalo zezibalo.