HMAC-based Extract-and-Expand Key Derivation Function (HKDF) as defined in RFC 5869. The HMAC is provided by libsodium which uses the HMAC-SHA-512/256 algorithm.
.package(url: "https://github.com/TICESoftware/HKDF.git", .upToNextMajor(from: "1.0.0"))
In order to build the library it is necessary to link libsodium. The official repository includes scripts to build binaries for specific platforms.
swift build -Xcc -I[header search path] -Xlinker -L[binary path]
When using Xcode you can set the header search path manually to include the libsodium header files and link the static libsodium library.
Sodium as a dependency which includes the pre-compiled libsodium library. No further setup necessary.
For deriving a new key of length 32 bytes from some input keying material
import HKDF let ikm = "Input key".bytes let hkdfKey = try! deriveHKDFKey(ikm: ikm, L: 32)
salt and some application specific info string (which is hashed into the HMAC) can additionally be provided:
try deriveHKDFKey(ikm: ikm, salt: salt, info: "Info", L: 32)