WebCrypto

WebCrypto, short for the Web Cryptography API, is a web standard that exposes cryptographic primitives to web applications within a browser. It enables client-side encryption, decryption, digital signatures, and key management in a secure, sandboxed environment, without external plug-ins. The API is accessed through the global Crypto interface and its subtle property, window.crypto.subtle, which provides asynchronous, Promise-based methods for cryptographic operations.

Core concepts include CryptoKey objects representing keys, which may be generated or imported; keys can be non-exportable to protect sensitive material. All operations are performed in the browser's cryptographic context and do not reveal key material unless explicitly exported in allowed forms.

Supported operations cover key generation, import and export, key derivation, encryption and decryption, digital signing and verification, and message digests. The API supports a range of algorithms, including AES (GCM, CBC, CTR, KW for key wrapping), HMAC, RSA (OAEP for encryption, RSASSA-PKCS1-v1_5 and RSASSA-PSS for signatures), ECDSA and ECDH, HKDF, PBKDF2, and hash algorithms such as SHA-256, SHA-384, and SHA-512. Not all algorithms are available in all browsers.

Usage considerations include the strong security model: private key material can be non-exportable, keys have specific usages, and operations are often performed asynchronously. WebCrypto is intended for cryptographic primitives rather than high-level protocols, and developers should implement proper security designs and rely on TLS for transport security.

History and status: developed by standards bodies such as W3C and WHATWG, WebCrypto has broad support in major browsers, with varying support for complete algorithm sets across versions. It is widely used to implement client-side encryption, integrity checks, and signature workflows in web applications.