Steffen Becker
2a20f1d107
Writes agile encryption with Word's own parameters (AES-256-CBC in 4096-byte segments, 100000 SHA-512 rounds, HMAC integrity) into a compound file built here — cfb.ts, MiniFAT and DIFAT included. Reads that and the older standard encryption LibreOffice writes, whose package is AES-ECB. Verified both ways against LibreOffice.
43 lines
1.8 KiB
TypeScript
43 lines
1.8 KiB
TypeScript
import { describe, it, expect } from 'vitest';
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import { readCfb, writeCfb, isCfb } from '../../src/lib/crypto/cfb';
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const bytes = (n: number, seed = 1) =>
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Uint8Array.from({ length: n }, (_, i) => (i * 31 + seed) & 0xff);
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describe('compound file container', () => {
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it('round-trips a mini stream and a big one in the same file', () => {
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const small = bytes(224);
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const large = bytes(9000, 7);
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const streams = readCfb(writeCfb([['EncryptionInfo', small], ['EncryptedPackage', large]]));
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expect(streams.get('EncryptionInfo')).toEqual(small);
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expect(streams.get('EncryptedPackage')).toEqual(large);
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});
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it('writes a header a reader recognizes', () => {
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const file = writeCfb([['EncryptionInfo', bytes(224)]]);
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expect(isCfb(file)).toBe(true);
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const view = new DataView(file.buffer);
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expect(view.getUint16(26, true)).toBe(3); // major version
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expect(view.getUint16(30, true)).toBe(9); // 512-byte sectors
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expect(view.getUint32(56, true)).toBe(4096); // mini stream cutoff
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expect(file.length % 512).toBe(0);
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});
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it('survives a stream past the first FAT sector', () => {
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// Over 64 KiB needs more than one FAT sector's worth of chain entries.
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const large = bytes(300_000, 3);
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expect(readCfb(writeCfb([['EncryptedPackage', large]])).get('EncryptedPackage')).toEqual(large);
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});
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it('handles an empty stream and exact sector multiples', () => {
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const streams = readCfb(writeCfb([['Empty', new Uint8Array(0)], ['Exact', bytes(4096)]]));
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expect(streams.get('Empty')!.length).toBe(0);
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expect(streams.get('Exact')).toEqual(bytes(4096));
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});
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it('refuses anything that is not a compound file', () => {
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expect(isCfb(new Uint8Array([0x50, 0x4b, 3, 4]))).toBe(false);
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expect(() => readCfb(new Uint8Array([0x50, 0x4b, 3, 4]))).toThrow();
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});
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});
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