psalami / HKDF

HMAC-based Extract-and-Expand Key Derivation Function (HKDF) in Swift

HKDF in Swift

HKDF is an HMAC based key derivation function that transforms any weak key material into cryptographically strong key material. It can be used, for example, to convert a session key derived in a secure remote password authentication into key material suitable for use in encryption, integrity checking or authentication.

Usage:

// Input Key Material (ikm): weak input key material.
let ikm = Data(bytes: try! Random.generate(byteCount: 16))

// Output Key Material (okm): strong key material.
let okm = deriveKey(algorithm: .sha256, seed: ikm, count: 32)

More information can be found in the documentation.

References:

• RFC 5869 - HMAC-based Extract-and-Expand Key Derivation Function (HKDF)

Credits

This library was written by Bouke Haarsma.