unikernel/duniverse/kdf/hkdf/hkdf.mli

@@ -0,0 +1,27 @@
+
+(** {{:https://tools.ietf.org/html/rfc5869}RFC 5869} specifies a HMAC-based
+    Extract-and-Expand Key Derivation Function (HKDF), which is abstracted over
+    a specific hash function. *)
+
+module type S = sig
+
+  (** [extract salt ikm] is [prk], the pseudorandom key of hash length octets.
+      The [salt] is an optional non-secret random value, [ikm] the input key
+      material. *)
+  val extract : ?salt:string -> string -> string
+
+  (** [extract prk info length] is [okm], the output keying material.  Given the
+  pseudorandom key of hash length (usually output of [!extract] step), and an
+  optional context and application specific information [info], the [okm] is
+  generated. *)
+  val expand : prk:string -> ?info:string -> int -> string
+end
+
+(** Given a Hash function, get the HKDF *)
+module Make (H : Digestif.S) : S
+
+(** convenience [extract hash salt ikm] where the [hash] has to be provided explicitly *)
+val extract : hash:Digestif.hash' -> ?salt:string -> string -> string
+
+(** convenience [expand hash prk info len] where the [hash] has to be provided explicitly *)
+val expand : hash:Digestif.hash' -> prk:string -> ?info:string -> int -> string