WebCrypt

Zero-dependency end-to-end encryption for the modern web.

AES-256-GCM symmetric encryption, RSA-4096 hybrid asymmetric encryption, ECDH key exchange, digital signatures, HMAC, and streaming file encryption — all powered by the native Web Crypto API with zero runtime dependencies.

Quick Start

npm install webcrypt

Encrypt and decrypt text:

import { WebCrypt } from "webcrypt";
const wc = new WebCrypt();

const encrypted = await wc.encryptText("Secret message", "my-password");
const decrypted = await wc.decryptText(encrypted, "my-password");

Encrypt a file:

const { blob, filename } = await wc.encryptFile(file, "my-password");

Public-key encryption (RSA-4096):

import { WebCryptAsym } from "webcrypt";
const wca = new WebCryptAsym();

const keys = await wca.generateKeyPair();
const encrypted = await wca.encryptText("Secret", keys.publicKey);
const decrypted = await wca.decryptText(encrypted, keys.privateKey);

Features

Feature	Status	Details
Text encryption	✅ Done	AES-256-GCM, returns base64 string
File encryption	✅ Done	Streaming — handles large files (1 GB size limit)
WebRTC E2EE	✅ Done	Insertable Streams for video + audio
Digital signatures	✅ Done	ECDSA, RSA-PSS
ECDH key exchange	✅ Done	P-256 / P-384 Diffie-Hellman
HMAC	✅ Done	SHA-256/384/512 and SHA-3
Key derivation	✅ Done	PBKDF2 (600k iterations), SHA-3 KDF, HKDF
Key caching	✅ Done	Safe unref'd timers & reference nulling
TypeScript	✅ Done	Full `.d.ts` for all modules
Zero dependencies	✅ Done	Pure Web Crypto API
JWE (JSON Web Encryption)	✅ Done	RFC 7516 Compact Serialization (RSA-OAEP/A256GCM)
Post-quantum (Kyber/Dilith)	⚠️ Stub	Stub mode testing guard — see docs/PQC.md

Modules

WebCrypt is split into three modules. Import only what you need:

import { WebCrypt } from "webcrypt"; // Symmetric (password-based)
import { WebCryptAsym } from "webcrypt"; // Asymmetric (public/private key)
import { WebCryptPQC } from "webcrypt"; // Post-quantum (⚠️ stub)

Module	Use case	Encryption	Quantum-safe?
`WebCrypt`	Password-based encryption	AES-256-GCM	✅ Yes (Grover-resistant)
`WebCryptAsym`	Public-key encryption	RSA-4096 + AES	⚠️ RSA vulnerable to Shor
`WebCryptPQC`	Post-quantum (future)	Kyber + Dilithium	⚠️ Stub — not real PQC yet

Symmetric Encryption (WebCrypt)

Password-based AES-256-GCM encryption with PBKDF2 key derivation (600,000 iterations).

Text

import { WebCrypt } from "webcrypt";
const wc = new WebCrypt();

const encrypted = await wc.encryptText("The treasure is buried under the oak tree", "password");
const decrypted = await wc.decryptText(encrypted, "password");

JSON Data

const data = { message: "Hello", users: ["Alice", "Bob"] };
const encrypted = await wc.encryptData(data, "password");
const decrypted = await wc.decryptData(encrypted, "password");
// decrypted.users → ["Alice", "Bob"]

Files

// Encrypt
const { blob, filename } = await wc.encryptFile(file, "password");

// Decrypt
const { blob: decrypted, filename: originalName } = await wc.decryptFile(encryptedBlob, "password");

WebRTC End-to-End Encryption

const wc = new WebCrypt();
const PASSWORD = "shared-call-secret";

const stream = await navigator.mediaDevices.getUserMedia({ video: true, audio: true });
const pc = new RTCPeerConnection();

// Encrypt outgoing
stream.getTracks().forEach(async track => {
  const sender = pc.addTrack(track, stream);
  sender.transform = new RTCRtpScriptTransform(await wc.createEncryptTransform(PASSWORD));
});

// Decrypt incoming
pc.ontrack = async event => {
  event.receiver.transform = new RTCRtpScriptTransform(await wc.createDecryptTransform(PASSWORD));
  document.getElementById("remoteVideo").srcObject = event.streams[0];
};

Both peers use the same password. The SFU/server sees only encrypted data.

Asymmetric Encryption (WebCryptAsym)

RSA-4096 hybrid encryption: RSA-OAEP encrypts an ephemeral AES-256-GCM session key, which encrypts the payload.

Encrypt / Decrypt

import { WebCryptAsym } from "webcrypt";
const crypt = new WebCryptAsym();

// Generate key pair
const keys = await crypt.generateKeyPair();

// Share public key
const publicKeyB64 = await crypt.exportPublicKey(keys.publicKey);

// Recipient imports and encrypts
const publicKey = await crypt.importPublicKey(publicKeyB64);
const encrypted = await crypt.encryptText("Secret message", publicKey);

// Decrypt with private key
const decrypted = await crypt.decryptText(encrypted, keys.privateKey);

ECDH Key Exchange

Derive a shared secret between two parties without transmitting any secret material.

// Each party generates an ECDH key pair
const alice = await crypt.generateECDHKeyPair();
const bob = await crypt.generateECDHKeyPair();

// Exchange public keys, then encrypt
const encrypted = await crypt.encryptWithECDH(
  { data: "Secret from Alice" },
  alice.privateKey,
  await crypt.importECDHPublicKey(bob.publicKeyB64)
);

// Recipient decrypts
const decrypted = await crypt.decryptWithECDH(
  encrypted,
  bob.privateKey,
  await crypt.importECDHPublicKey(alice.publicKeyB64)
);
// decrypted.data → "Secret from Alice"

Digital Signatures (ECDSA)

// Generate signing key pair
const { publicKey, privateKey, publicKeyB64 } = await crypt.generateSigningKeyPair("P-256");

// Sign
const signature = await crypt.signText("I approve transaction #123", privateKey);

// Verify
const valid = await crypt.verifyText("I approve transaction #123", signature, publicKey);
// valid === true

// Sign/verify files (detached signatures)
const { signatureB64 } = await crypt.signFile(file, privateKey);
const fileValid = await crypt.verifyFile(file, signatureB64, publicKey);

File Encryption with Progress

const { blob, filename } = await crypt.encryptFileWithProgress(file, publicKey, progress => {
  console.log(`${Math.round(progress * 100)}%`);
});

JSON Web Encryption (JWE)

Create and decrypt standard JWE Compact Serialization tokens (RFC 7516) using RSA-OAEP-256 and A256GCM.

import { WebCryptAsym } from "webcrypt";
const crypt = new WebCryptAsym();

// Generate or import key pair
const keys = await crypt.generateKeyPair();

// Encrypt payload into a JWE string
const payload = { userId: 123, role: "admin" };
const jweToken = await crypt.encryptJWE(payload, keys.publicKey, { kid: "my-key-id" });

// Decrypt JWE token
const decrypted = await crypt.decryptJWE(jweToken, keys.privateKey);
// decrypted.role → "admin"

HMAC

Message authentication codes using SHA-256, SHA-384, SHA-512, or SHA-3.

import { WebCrypt } from "webcrypt";
const wc = new WebCrypt();

// Generate key and compute HMAC
const key = await wc.generateHmacKey("password");
const hmac = await wc.computeHmac("Important message", key);

// Verify
const valid = await wc.verifyHmac("Important message", hmac, key); // true

// SHA-3 variant (quantum-resistant)
const sha3Key = await wc.generateHmacKeySHA3("password");
const sha3Hmac = await wc.computeHmacSHA3("Important message", sha3Key);
const sha3Valid = await wc.verifyHmacSHA3("Important message", sha3Hmac, sha3Key);

Key Derivation

PBKDF2 (default)

const key = await crypt.deriveKeyPBKDF2("password", "salt"); // 600,000 iterations

SHA-3 KDF

const key = await crypt.deriveKeySHA3("password", 50000, "SHA3-256");

HKDF-SHA3

const masterSecret = new TextEncoder().encode("master-password");
const key = await crypt.deriveKeyHKDFSHA3(masterSecret, saltBytes, infoBytes, 256);

Key rotation and hierarchical keys

// Rotate with a new salt
const rotatedKey = await crypt.rotateKeyNew("password", newSaltBytes, "PBKDF2");

// Derive child keys for different purposes
const encKey = await crypt.deriveChildKeyHierarchical(parentKey, childSalt, "encryption");
const sigKey = await crypt.deriveChildKeyHierarchical(parentKey, childSalt, "signing");

Post-Quantum Cryptography

⚠️ STUB IMPLEMENTATION — WebCryptPQC currently uses SHA-3 hashing stubs, not real lattice-based cryptography. For production PQC, integrate liboqs-js directly.

WebCryptPQC provides a placeholder API for Kyber (key encapsulation) and Dilithium (digital signatures) that mirrors the real API surface. Build against it today, swap in real PQC when v0.6+ ships.

import { WebCryptPQC } from "webcrypt";
const pqc = new WebCryptPQC(); // ⚠️ Warns about stub status

const kyberKeys = await pqc.generateKyberKeyPair("Kyber768");
const { ciphertext, sharedSecret } = await pqc.kyberEncapsulate(kyberKeys.publicKey, "Kyber768");
const recovered = await pqc.kyberDecapsulate(ciphertext, kyberKeys.privateKey, "Kyber768");

Full PQC documentation: docs/PQC.md — includes Kyber, Dilithium, hybrid encryption, security levels, and migration path.

API Reference

WebCrypt (Symmetric)

const wc = new WebCrypt();

// Text
wc.encryptText(text: string, password: string): Promise<string>
wc.decryptText(b64: string, password: string): Promise<string>

// JSON data
wc.encryptData(data: any, password: string): Promise<string>
wc.decryptData(b64: string, password: string): Promise<any>

// Files
wc.encryptFile(file: File | Blob, password: string): Promise<{ blob: Blob, filename: string }>
wc.decryptFile(file: File | Blob, password: string): Promise<{ blob: Blob, filename: string }>

// WebRTC E2EE
wc.createEncryptTransform(password: string): Promise<TransformFunction>
wc.createDecryptTransform(password: string): Promise<TransformFunction>

// HMAC
wc.generateHmacSalt(length?: number): Uint8Array
wc.generateHmacKey(password?: string, hash?: string, salt?: Uint8Array | string): Promise<CryptoKey>
wc.computeHmac(data: string | ArrayBuffer, key: CryptoKey): Promise<string>
wc.verifyHmac(data: string | ArrayBuffer, hmac: string, key: CryptoKey): Promise<boolean>

// HMAC-SHA3
wc.generateHmacKeySHA3(password?: string, hash?: string, salt?: Uint8Array | string): Promise<CryptoKey>
wc.computeHmacSHA3(data: string | ArrayBuffer, key: CryptoKey): Promise<string>
wc.verifyHmacSHA3(data: string | ArrayBuffer, hmac: string, key: CryptoKey): Promise<boolean>

// Utilities
wc.generateRandomPassword(length?: number): string
wc.clearKeyCache(): void
wc.stopAutoCleanup(): void

WebCryptAsym (Asymmetric)

const crypt = new WebCryptAsym();

// Key management
crypt.generateKeyPair(modulusLength?: number): Promise<CryptoKeyPair>
crypt.exportPublicKey(key: CryptoKey): Promise<string>
crypt.exportPrivateKey(key: CryptoKey): Promise<string>
crypt.importPublicKey(b64: string): Promise<CryptoKey>
crypt.importPrivateKey(b64: string): Promise<CryptoKey>

// Text
crypt.encryptText(text: string, publicKey: CryptoKey): Promise<string>
crypt.decryptText(b64: string, privateKey: CryptoKey): Promise<string>

// JSON data
crypt.encryptData(data: any, publicKey: CryptoKey): Promise<string>
crypt.decryptData(b64: string, privateKey: CryptoKey): Promise<any>

// Files
crypt.encryptFile(file: File | Blob, publicKey: CryptoKey): Promise<{ blob, filename }>
crypt.decryptFile(file: File | Blob, privateKey: CryptoKey): Promise<{ blob, filename }>
crypt.encryptFileWithProgress(file, publicKey, onProgress?): Promise<{ blob, filename }>
crypt.decryptFileWithProgress(file, privateKey, onProgress?): Promise<{ blob, filename }>

// ECDH key exchange
crypt.generateECDHKeyPair(curve?: string): Promise<{ publicKey, privateKey, publicKeyB64 }>
crypt.exportECDHPublicKey(key: CryptoKey): Promise<string>
crypt.importECDHPublicKey(b64: string, curve?: string): Promise<CryptoKey>
crypt.deriveECDHSharedSecret(privateKey: CryptoKey, peerPublicKey: CryptoKey): Promise<CryptoKey>
crypt.encryptWithECDH(data: any, privateKey, recipientPublicKey): Promise<string>
crypt.decryptWithECDH(b64: string, privateKey, senderPublicKey): Promise<any>

// Digital Signatures (ECDSA / RSA-PSS)
crypt.generateSigningKeyPair(curve?: string): Promise<{ publicKey, privateKey, publicKeyB64 }>
crypt.generateEdDSASigningKeyPair(): Promise<{ publicKey, privateKey, publicKeyB64 }>
crypt.generateRSAPSSigningKeyPair(modulusLength?: number): Promise<{ publicKey, privateKey, publicKeyB64 }>
crypt.importPublicSigningKey(b64: string, curve?: string): Promise<CryptoKey>
crypt.signText(text: string, privateKey: CryptoKey): Promise<string>
crypt.verifyText(text: string, sig: string, publicKey: CryptoKey): Promise<boolean>
crypt.signFile(file: File | Blob, privateKey: CryptoKey): Promise<{ signatureB64, blob }>
crypt.verifyFile(file: File | Blob, sig: string, publicKey: CryptoKey): Promise<boolean>
crypt.signTextWithAlgorithm(text, privateKey, algorithm?: 'ECDSA' | 'RSA-PSS'): Promise<string>
crypt.verifyTextWithAlgorithm(text, sig, publicKey, algorithm?: 'ECDSA' | 'RSA-PSS'): Promise<boolean>

// JWE (JSON Web Encryption)
crypt.encryptJWE(payload: any, publicKey: CryptoKey, headers?: object): Promise<string>
crypt.decryptJWE(jweToken: string, privateKey: CryptoKey): Promise<any>

// MAC & Poly1305
crypt.signHMAC(data: string, key: CryptoKey, hash?: string): Promise<string>
crypt.verifyHMAC(data: string, sig: string, key: CryptoKey, hash?: string): Promise<boolean>
crypt.authenticatePoly1305(data: string | Uint8Array, key: Uint8Array): Promise<string>

// Key derivation & rotation
crypt.deriveKeyPBKDF2(password, salt, iterations?, hash?, keyLength?): Promise<CryptoKey>
crypt.deriveKeyArgon2(password, salt, options?): Promise<CryptoKey>
crypt.deriveKeySHA3(password, iterations?, algorithm?): Promise<CryptoKey>
crypt.deriveKeyHKDFSHA2(secret, salt?, info?, keyLength?): Promise<CryptoKey>
crypt.deriveKeyHKDFSHA3(secret, salt?, info?, keyLength?): Promise<CryptoKey>
crypt.generateKeyFromPassword(password, salt, algorithm?): Promise<CryptoKey>
crypt.generateRotatingKey(password, salt, algorithm?, rotationCount?): Promise<CryptoKey>
crypt.generateHierarchicalKey(masterPassword, path: string[]): Promise<{ masterKey, childKeys }>
crypt.generateKeyFromMultipleInputs(inputs: string[], salt, algorithm?): Promise<CryptoKey>
crypt.rotateKeyNew(password, newSalt, method?): Promise<CryptoKey>
crypt.deriveChildKeyHierarchical(parentKey, childSalt, purpose?): Promise<CryptoKey>
crypt.secureRandom(length: number): Promise<Uint8Array>
crypt.secureKeyErase(key: Uint8Array): void

// WebRTC Insertable Streams
crypt.createEncryptTransform(publicKey: CryptoKey): Promise<TransformFunction>
crypt.createDecryptTransform(privateKey: CryptoKey): Promise<TransformFunction>
crypt.createHybridEncryptTransform(publicKey, kyberPublicKey, level?): Promise<TransformFunction>
crypt.createEncryptTransformWithProgress(publicKey, onProgress?): Promise<TransformFunction>

WebCryptPQC (Post-Quantum)

See docs/PQC.md for the full API reference.

Security

What's quantum-safe today

Layer	Algorithm	Quantum status
Symmetric encryption	AES-256-GCM	✅ Safe — 128-bit security even with Grover
Key derivation	PBKDF2 600k	✅ Safe — no quantum speedup for password cracking
HMAC	SHA-256/3	✅ Safe — collision resistance holds
Asymmetric encryption	RSA-4096	⚠️ Vulnerable to Shor's algorithm (est. 2030–2040)
Signatures	ECDSA	⚠️ Vulnerable to Shor's algorithm
PQC (Kyber/Dilithium)	Stubs	❌ Not real PQC yet

Security hardening (v0.6.5)

PBKDF2 Iterations: 600,000 (OWASP 2025+ compliant).
Non-Exportable HMAC Keys: Generated HMAC keys pass extractable: false to crypto.subtle.importKey preventing secret key extraction while allowing full signing and verification.
Constant-Time Verification Contract: TimingSafeHelper.timingSafeVerify() catches signature verification failures and returns false with padding instead of re-throwing exceptions.
PQC Stub Guard: WebCryptPQC._STUB_MODE throws explicit errors on production calls unless WebCryptPQC.enableStubTesting(true) is explicitly enabled for unit testing.
Safe Memory Cleanup: Map mutations are isolated prior to deletion in clearKeyCache() and secret CryptoKey references are nulled.
Stack-Safe Base64: Uses 1024-byte chunking in Base64 encoding/decoding, eliminating call stack overflow risks across JS runtimes.
Base64 Padding Resilience: _base64ToArrayBuffer() automatically normalizes unpadded Base64 strings.
Increased File Payload Limit: MAX_ENCRYPTED_DATA_SIZE increased to 1 GB for large file streaming.
Full-Entropy Random Passwords: generateRandomPassword() returns full-entropy hexadecimal strings derived via crypto.getRandomValues.
SHA-3 Fallback Warning: Explicit console.warn logging when SHA-3 falls back to SHA-256/384/512 in standard Web Crypto runtimes.
Sanitized Production Logs: Detailed internal error logging gated behind NODE_ENV !== "production".

Known limitations

PQC is a stub — Kyber/Dilithium use SHA-3 hashing, not real lattice-based crypto
Argon2id is not supported by Web Crypto API — falls back to PBKDF2 with a warning
JavaScript cannot guarantee secure memory erasure — key cleanup is best-effort
WebRTC E2EE uses a fixed salt for key derivation from passwords

For vulnerability reporting, see SECURITY.md.
For security fix details, see SECURITY_FIXES.md.

Environment Support

Browser: Chrome 80+ · Edge 80+ · Firefox 90+ · Safari 15+
Runtime: Node.js 18+ · Deno · Cloudflare Workers · Electron
Frameworks: React · Next.js · Vue · Angular · Svelte

// ES Modules
import { WebCrypt } from "webcrypt";

// CommonJS
const { WebCrypt } = require("webcrypt");

License

Legal & Usage Disclaimers

Warning

Limitation of Liability & Disclaimer of Warranty
WebCrypt is maintained by PuterVision LLC and provided "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NONINFRINGEMENT. IN NO EVENT SHALL PUTERVISION LLC, ITS AFFILIATES, OR CONTRIBUTORS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF, OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. USERS AND DEVELOPERS ARE SOLELY RESPONSIBLE FOR VERIFYING CRYPTOGRAPHIC PARAMETERS, CONDUCTING INDEPENDENT SECURITY AUDITS, AND DETERMINING SUITABILITY FOR PRODUCTION DEPLOYMENTS.

Note

Data Privacy & Local Execution Guarantee
WebCrypt operations execute 100% locally in your browser or Node.js runtime using the native Web Crypto API. No private keys, passwords, plaintext data, or encrypted payloads are ever transmitted to external cloud servers.

Important

Third-Party AI Model & API Fees Disclaimer
This software is provided as free, open-source software under the MIT License. If integrated into developer AI agent frameworks (such as OpenAI, Anthropic Claude, Google Gemini, xAI Grok, or Ollama), any third-party API usage and billing fees remain the sole responsibility of the user. PuterVision LLC is not responsible for third-party API costs.

Note

Trademark & Open Specification Attributions
Model Context Protocol (MCP) is an open specification created by Anthropic, PBC. Web Crypto API, W3C standards, and third-party IDE trademarks are property of their respective owners. PuterVision LLC is an independent open-source software developer.

Note

Performance & Cost Savings Estimates
Encryption performance benchmarks, throughput speeds, and zero-dependency efficiency metrics reported in documentation are derived from standard browser and Node.js WebCrypto benchmarks and may vary based on hardware acceleration.

Name		Name	Last commit message	Last commit date
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.agents		.agents
.cursor		.cursor
.gemini		.gemini
.github		.github
__tests__		__tests__
docs		docs
examples		examples
src		src
.gitignore		.gitignore
.windsurfrules		.windsurfrules
CHANGELOG.md		CHANGELOG.md
CLAUDE.md		CLAUDE.md
CONTRIBUTING.md		CONTRIBUTING.md
LICENSE		LICENSE
README.md		README.md
SECURITY.md		SECURITY.md
SECURITY_FIXES.md		SECURITY_FIXES.md
jest.config.js		jest.config.js
jest.setup.js		jest.setup.js
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package.json		package.json

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WebCrypt

Quick Start

Table of Contents

Features

Modules

Symmetric Encryption (WebCrypt)

Text

JSON Data

Files

WebRTC End-to-End Encryption

Asymmetric Encryption (WebCryptAsym)

Encrypt / Decrypt

ECDH Key Exchange

Digital Signatures (ECDSA)

File Encryption with Progress

JSON Web Encryption (JWE)

HMAC

Key Derivation

PBKDF2 (default)

SHA-3 KDF

HKDF-SHA3

Key rotation and hierarchical keys

Post-Quantum Cryptography

API Reference

WebCrypt (Symmetric)

WebCryptAsym (Asymmetric)

WebCryptPQC (Post-Quantum)

Security

What's quantum-safe today

Security hardening (v0.6.5)

Known limitations

Environment Support

License

Legal & Usage Disclaimers

About

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Resources

Contributing

Security policy

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