40 lines
1.6 KiB
TypeScript
40 lines
1.6 KiB
TypeScript
import crypto from "node:crypto";
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const APP_KEY_MATERIAL = "MDD-v2-backup-aes256gcm-2026";
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const ALGORITHM = "aes-256-gcm";
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const IV_LENGTH = 12;
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const AUTH_TAG_LENGTH = 16;
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const MAGIC = Buffer.from("MDD1");
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function deriveKey(): Buffer {
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return crypto.createHash("sha256").update(APP_KEY_MATERIAL).digest();
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}
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export function encryptBackup(plaintext: string): Buffer {
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const key = deriveKey();
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const iv = crypto.randomBytes(IV_LENGTH);
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const cipher = crypto.createCipheriv(ALGORITHM, key, iv, { authTagLength: AUTH_TAG_LENGTH });
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const encrypted = Buffer.concat([cipher.update(plaintext, "utf8"), cipher.final()]);
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const authTag = cipher.getAuthTag();
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return Buffer.concat([MAGIC, iv, authTag, encrypted]);
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}
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export function decryptBackup(data: Buffer): string {
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if (data.length < MAGIC.length + IV_LENGTH + AUTH_TAG_LENGTH) {
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throw new Error("Backup-Datei zu kurz oder ungültig");
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}
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const magic = data.subarray(0, MAGIC.length);
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if (!magic.equals(MAGIC)) {
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throw new Error("Keine gültige MDD-Backup-Datei (falsche Signatur)");
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}
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const iv = data.subarray(MAGIC.length, MAGIC.length + IV_LENGTH);
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const authTag = data.subarray(MAGIC.length + IV_LENGTH, MAGIC.length + IV_LENGTH + AUTH_TAG_LENGTH);
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const ciphertext = data.subarray(MAGIC.length + IV_LENGTH + AUTH_TAG_LENGTH);
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const key = deriveKey();
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const decipher = crypto.createDecipheriv(ALGORITHM, key, iv, { authTagLength: AUTH_TAG_LENGTH });
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decipher.setAuthTag(authTag);
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const decrypted = Buffer.concat([decipher.update(ciphertext), decipher.final()]);
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return decrypted.toString("utf8");
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}
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