mirror of
https://github.com/ramvignesh-b/pi-ku.git
synced 2026-05-04 08:56:52 +00:00
feat: implement master key derivation and persistence via IndexedDB
This commit is contained in:
Your Name
+213
-213
@@ -11,70 +11,7 @@ export interface EncryptedLetter {
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export interface EncryptedImageUpload {
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encryptedBlob: Blob;
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encrypted_dek: string;
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sharingKey: string;
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}
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const PBKDF2_ITERATIONS = 100_000;
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const AES_GCM = { name: "AES-GCM", length: 256 } as const;
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// base64 conversion for transit
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const toBase64 = (buf: Uint8Array): string =>
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btoa(buf.reduce((s, b) => s + String.fromCharCode(b), ""));
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// explicit loop ensures Uint8Array<ArrayBuffer> (not ArrayBufferLike)
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const fromBase64 = (b64: string): Uint8Array<ArrayBuffer> => {
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const str = atob(b64);
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const arr = new Uint8Array(str.length);
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for (let i = 0; i < str.length; i++) arr[i] = str.charCodeAt(i);
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return arr;
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};
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// bundle IV + data into a single base64 string
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const packWithIv = (iv: Uint8Array, data: ArrayBuffer): string => {
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const packed = new Uint8Array(iv.length + data.byteLength);
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packed.set(iv);
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packed.set(new Uint8Array(data), iv.length);
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return toBase64(packed);
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};
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// split IV (first 12 bytes) back out from a packed base64 bundle
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const unpackWithIv = (
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b64: string,
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): [Uint8Array<ArrayBuffer>, Uint8Array<ArrayBuffer>] => {
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const buf = fromBase64(b64); // ArrayBuffer-backed, so buf.buffer is ArrayBuffer
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return [new Uint8Array(buf.buffer, 0, 12), new Uint8Array(buf.buffer, 12)];
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};
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/**
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* Derives a Master Key from a password and email (salt).
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* Deterministic — same credentials always produce the same key.
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*/
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export async function deriveMasterKey(
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password: string,
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email: string,
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): Promise<CryptoKey> {
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const enc = new TextEncoder();
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const baseKey = await crypto.subtle.importKey(
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"raw",
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enc.encode(password),
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"PBKDF2",
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false,
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["deriveKey"],
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);
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return crypto.subtle.deriveKey(
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{
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name: "PBKDF2",
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salt: enc.encode(email.toLowerCase()),
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iterations: PBKDF2_ITERATIONS,
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hash: "SHA-256",
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},
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baseKey,
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AES_GCM,
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false,
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["encrypt", "decrypt", "wrapKey", "unwrapKey"],
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);
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filename: string;
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}
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/*
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@@ -86,161 +23,224 @@ interface SealedEnvelope {
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sharingKey: string;
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}
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async function sealEnvelope(
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input: Uint8Array,
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masterKey: CryptoKey,
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): Promise<SealedEnvelope> {
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// copy into a fresh ArrayBuffer — WebCrypto requires ArrayBuffer-backed arrays
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const plainBytes = new Uint8Array(input);
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export class CryptoUtils {
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private dek: CryptoKey = {} as CryptoKey;
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private static readonly PBKDF2_ITERATIONS = 100_000;
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private static readonly AES_GCM = { name: "AES-GCM", length: 256 };
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// 1-time DEK for this payload
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const dek = await crypto.subtle.generateKey(AES_GCM, true, [
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"encrypt",
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"decrypt",
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]);
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async initialize() {
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this.dek = await crypto.subtle.generateKey(CryptoUtils.AES_GCM, true, [
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"encrypt",
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"decrypt",
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]);
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}
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// encrypt the content with the DEK
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const contentIv = crypto.getRandomValues(new Uint8Array(12));
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const ciphertext = await crypto.subtle.encrypt(
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{ name: "AES-GCM", iv: contentIv },
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dek,
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plainBytes,
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);
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// base64 conversion for transit
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toBase64 = (buf: Uint8Array): string =>
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btoa(buf.reduce((s, b) => s + String.fromCharCode(b), ""));
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// wrap the DEK with the Master Key (for self/owner access)
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const dekIv = crypto.getRandomValues(new Uint8Array(12));
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const wrappedDek = await crypto.subtle.wrapKey("raw", dek, masterKey, {
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name: "AES-GCM",
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iv: dekIv,
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});
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// export raw DEK for the share URL (recipient access, no master key needed)
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const rawDek = await crypto.subtle.exportKey("raw", dek);
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return {
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encryptedContent: packWithIv(contentIv, ciphertext),
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encrypted_dek: packWithIv(dekIv, wrappedDek),
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sharingKey: toBase64(new Uint8Array(rawDek)),
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// explicit loop ensures Uint8Array<ArrayBuffer> (not ArrayBufferLike)
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fromBase64 = (b64: string): Uint8Array<ArrayBuffer> => {
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const str = atob(b64);
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const arr = new Uint8Array(str.length);
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for (let i = 0; i < str.length; i++) arr[i] = str.charCodeAt(i);
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return arr;
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};
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}
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async function openEnvelope(
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encryptedContent: string,
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encrypted_dek: string,
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masterKey: CryptoKey,
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): Promise<Uint8Array<ArrayBuffer>> {
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// unwrap the DEK using the master key
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const [dekIv, wrappedDek] = unpackWithIv(encrypted_dek);
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const dek = await crypto.subtle.unwrapKey(
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"raw",
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wrappedDek,
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masterKey,
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{ name: "AES-GCM", iv: dekIv },
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AES_GCM,
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false,
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["decrypt"],
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);
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// decrypt the content with the recovered DEK
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const [contentIv, ciphertext] = unpackWithIv(encryptedContent);
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const plainBytes = await crypto.subtle.decrypt(
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{ name: "AES-GCM", iv: contentIv },
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dek,
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ciphertext,
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);
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return new Uint8Array(plainBytes);
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}
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/*
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* Letter functions
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*/
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export async function encryptLetter(
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plaintext: string,
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masterKey: CryptoKey,
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): Promise<EncryptedLetter> {
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const { encryptedContent, encrypted_dek, sharingKey } = await sealEnvelope(
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new TextEncoder().encode(plaintext),
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masterKey,
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);
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return { encrypted_content: encryptedContent, encrypted_dek, sharingKey };
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}
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export async function decryptLetter(
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{ encrypted_content, encrypted_dek }: EncryptedLetter,
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masterKey: CryptoKey,
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): Promise<string> {
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const plainBytes = await openEnvelope(
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encrypted_content,
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encrypted_dek,
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masterKey,
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);
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return new TextDecoder().decode(plainBytes);
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}
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/*
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* Metadata functions
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*/
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export async function encryptMetadata(
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metadata: Record<string, string>,
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masterKey: CryptoKey,
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): Promise<EncryptedLetter> {
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const { encryptedContent, encrypted_dek, sharingKey } = await sealEnvelope(
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new TextEncoder().encode(JSON.stringify(metadata)),
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masterKey,
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);
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return { encrypted_content: encryptedContent, encrypted_dek, sharingKey };
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}
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export async function decryptMetadata(
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encrypted_metadata: EncryptedLetter,
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masterKey: CryptoKey,
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): Promise<Record<string, string>> {
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const plainBytes = await openEnvelope(
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encrypted_metadata.encrypted_content,
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encrypted_metadata.encrypted_dek,
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masterKey,
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);
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return JSON.parse(new TextDecoder().decode(plainBytes));
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}
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/*
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* Image functions
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*/
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export async function encryptImage(
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file: File,
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masterKey: CryptoKey,
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): Promise<EncryptedImageUpload> {
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const plainBytes = new Uint8Array(await file.arrayBuffer());
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const { encryptedContent, encrypted_dek, sharingKey } = await sealEnvelope(
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plainBytes,
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masterKey,
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);
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return {
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encryptedBlob: new Blob([fromBase64(encryptedContent)]),
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encrypted_dek,
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sharingKey,
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// bundle IV + data into a single base64 string
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packWithIv = (iv: Uint8Array, data: ArrayBuffer): string => {
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const packed = new Uint8Array(iv.length + data.byteLength);
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packed.set(iv);
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packed.set(new Uint8Array(data), iv.length);
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return this.toBase64(packed);
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};
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}
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export async function decryptImage(
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encryptedUrl: string,
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encrypted_dek: string,
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masterKey: CryptoKey,
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): Promise<string> {
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// fetch encrypted bytes from server and repack as base64 for openEnvelope
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const encryptedBytes = new Uint8Array(
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await (await fetch(encryptedUrl)).arrayBuffer(),
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);
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const plainBytes = await openEnvelope(
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toBase64(encryptedBytes),
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encrypted_dek,
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masterKey,
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);
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// split IV (first 12 bytes) back out from a packed base64 bundle
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unpackWithIv = (
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b64: string,
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): [Uint8Array<ArrayBuffer>, Uint8Array<ArrayBuffer>] => {
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const buf = this.fromBase64(b64); // ArrayBuffer-backed, so buf.buffer is ArrayBuffer
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return [new Uint8Array(buf.buffer, 0, 12), new Uint8Array(buf.buffer, 12)];
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};
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// return as object URL for use in Fabric / <img>
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return URL.createObjectURL(new Blob([plainBytes]));
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/**
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* Derives a Master Key from a password and email (salt).
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* Deterministic — same credentials always produce the same key.
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*/
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public static async deriveMasterKey(
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password: string,
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email: string,
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): Promise<CryptoKey> {
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const enc = new TextEncoder();
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const baseKey = await crypto.subtle.importKey(
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"raw",
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enc.encode(password),
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"PBKDF2",
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false,
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["deriveKey"],
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);
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return crypto.subtle.deriveKey(
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{
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name: "PBKDF2",
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salt: enc.encode(email.toLowerCase()),
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iterations: CryptoUtils.PBKDF2_ITERATIONS,
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hash: "SHA-256",
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},
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baseKey,
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CryptoUtils.AES_GCM,
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false,
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["encrypt", "decrypt", "wrapKey", "unwrapKey"],
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);
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}
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private async sealEnvelope(
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input: Uint8Array,
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masterKey: CryptoKey,
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): Promise<SealedEnvelope> {
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// copy into a fresh ArrayBuffer — WebCrypto requires ArrayBuffer-backed arrays
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const plainBytes = new Uint8Array(input);
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// encrypt the content with the DEK
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const contentIv = crypto.getRandomValues(new Uint8Array(12));
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const ciphertext = await crypto.subtle.encrypt(
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{ name: "AES-GCM", iv: contentIv },
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this.dek,
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plainBytes,
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);
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// wrap the DEK with the Master Key (for self/owner access)
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const dekIv = crypto.getRandomValues(new Uint8Array(12));
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const wrappedDek = await crypto.subtle.wrapKey("raw", this.dek, masterKey, {
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name: "AES-GCM",
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iv: dekIv,
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});
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// export raw DEK for the share URL (recipient access, no master key needed)
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const rawDek = await crypto.subtle.exportKey("raw", this.dek);
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return {
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encryptedContent: this.packWithIv(contentIv, ciphertext),
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encrypted_dek: this.packWithIv(dekIv, wrappedDek),
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sharingKey: this.toBase64(new Uint8Array(rawDek)),
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};
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}
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private async openEnvelope(
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encryptedContent: string,
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encrypted_dek: string,
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masterKey: CryptoKey,
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): Promise<Uint8Array<ArrayBuffer>> {
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// unwrap the DEK using the master key
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const [dekIv, wrappedDek] = this.unpackWithIv(encrypted_dek);
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const dek = await crypto.subtle.unwrapKey(
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"raw",
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wrappedDek,
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masterKey,
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{ name: "AES-GCM", iv: dekIv },
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CryptoUtils.AES_GCM,
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false,
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["decrypt"],
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);
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// decrypt the content with the recovered DEK
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const [contentIv, ciphertext] = this.unpackWithIv(encryptedContent);
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const plainBytes = await crypto.subtle.decrypt(
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{ name: "AES-GCM", iv: contentIv },
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dek,
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ciphertext,
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);
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return new Uint8Array(plainBytes);
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}
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/*
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* Letter functions
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*/
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public async encryptLetter(
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plaintext: string,
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masterKey: CryptoKey,
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): Promise<EncryptedLetter> {
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const { encryptedContent, encrypted_dek, sharingKey } =
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await this.sealEnvelope(new TextEncoder().encode(plaintext), masterKey);
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return { encrypted_content: encryptedContent, encrypted_dek, sharingKey };
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}
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public async decryptLetter(
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{ encrypted_content, encrypted_dek }: EncryptedLetter,
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masterKey: CryptoKey,
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): Promise<string> {
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const plainBytes = await this.openEnvelope(
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encrypted_content,
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encrypted_dek,
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masterKey,
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);
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return new TextDecoder().decode(plainBytes);
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}
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/*
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* Metadata functions
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*/
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public async encryptMetadata(
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metadata: Record<string, string>,
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masterKey: CryptoKey,
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): Promise<EncryptedLetter> {
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const { encryptedContent, encrypted_dek, sharingKey } =
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await this.sealEnvelope(
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new TextEncoder().encode(JSON.stringify(metadata)),
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masterKey,
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);
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return { encrypted_content: encryptedContent, encrypted_dek, sharingKey };
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}
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public async decryptMetadata(
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encrypted_metadata: EncryptedLetter,
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masterKey: CryptoKey,
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): Promise<Record<string, string>> {
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const plainBytes = await this.openEnvelope(
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encrypted_metadata.encrypted_content,
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encrypted_metadata.encrypted_dek,
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masterKey,
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);
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return JSON.parse(new TextDecoder().decode(plainBytes));
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}
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/*
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* Image functions
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*/
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public async encryptImage(
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file: File,
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masterKey: CryptoKey,
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): Promise<EncryptedImageUpload> {
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const plainBytes = new Uint8Array(await file.arrayBuffer());
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const { encryptedContent, encrypted_dek } = await this.sealEnvelope(
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plainBytes,
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masterKey,
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);
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return {
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encryptedBlob: new Blob([this.fromBase64(encryptedContent)]),
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encrypted_dek,
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filename: `${crypto.randomUUID()}.bin`,
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};
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}
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public async decryptImage(
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encryptedBlob: Blob,
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encrypted_dek: string,
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masterKey: CryptoKey,
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): Promise<string> {
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const encryptedBytes = new Uint8Array(await encryptedBlob.arrayBuffer());
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const plainBytes = await this.openEnvelope(
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this.toBase64(encryptedBytes),
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encrypted_dek,
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masterKey,
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);
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// return as object URL for use in Fabric / <img>
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return URL.createObjectURL(new Blob([plainBytes]));
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}
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}
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