Improve readability

sander · Jan 4, 2025 · 4e9b4a7 · 4e9b4a7
1 parent 7b64211
commit 4e9b4a7
Showing 1 changed file with 36 additions and 37 deletions.
diff --git a/prototype.lisp b/prototype.lisp
@@ -71,49 +71,49 @@
 (defparameter *Nsk* 32)
 (defparameter *suite_id* (|| (ASCII "KEM") (I2OSP #x0010 2)))
 (defparameter *bitmask* #xff)
-(labels ((LabeledExtract (salt label ikm)
-           (HKDF-Extract salt (|| (ASCII "HPKE-v1") *suite_id* label ikm)))
-         (LabeledExpand (prk label info L)
-           (HKDF-Expand
-            prk (|| (I2OSP L 2) (ASCII "HPKE-v1") *suite_id* label info)
-            L))
-         (ExtractAndExpand (dh kem_context)
-           (let* ((eae_prk (LabeledExtract (ASCII "") (ASCII "eae_prk") dh))
-                  (shared_secret
-                    (LabeledExpand
-                     eae_prk (ASCII "shared_secret") kem_context *Nsecret*)))
-             shared_secret))
-         (GenerateKeyPair ()
-           (let ((sk (EC-Random))) (values sk (EC-Scalar-Base-Mult sk))))
-         (SerializePublicKey (pk)
-           (|| (I2OSP (getf (crypto:ec-destructure-point pk) :x) 32)
-               (I2OSP (getf (crypto:ec-destructure-point pk) :y) 32)))
-         (DeserializePublicKey (b)
-           (crypto:ec-make-point
-            *EC* :x (OS2IP (subseq b 0 32)) :y (OS2IP (subseq b 32)))))
-  (defun KEM-Derive-Key-Pair (ikm) ;; todo test vectors
-    (loop with dkp_prk = (LabeledExtract (ASCII "") (ASCII "dkp_prk") ikm)
+(labels
+    ((labeled-extract (salt label ikm)
+       (HKDF-Extract salt (|| (ASCII "HPKE-v1") *suite_id* (ASCII label) ikm)))
+     (labeled-expand (prk label info L)
+       (HKDF-Expand prk (|| (I2OSP L 2) (ASCII "HPKE-v1")
+                            *suite_id* (ASCII label) info)
+                    L))
+     (extract-and-expand (dh kem_context)
+       (let* ((eae_prk (labeled-extract (ASCII "") "eae_prk" dh))
+              (shared_secret
+                (labeled-expand eae_prk "shared_secret" kem_context *Nsecret*)))
+         shared_secret))
+     (generate-key-pair ()
+       (let ((sk (EC-Random))) (values sk (EC-Scalar-Base-Mult sk))))
+     (serialize-public-key (pk)
+       (|| (I2OSP (getf (crypto:ec-destructure-point pk) :x) 32)
+           (I2OSP (getf (crypto:ec-destructure-point pk) :y) 32)))
+     (deserialize-public-key (b)
+       (crypto:ec-make-point *EC* :x (OS2IP (subseq b 0 32))
+                                  :y (OS2IP (subseq b 32)))))
+  (defun KEM-Derive-Key-Pair (ikm)
+    (loop with dkp_prk = (labeled-extract (ASCII "") "dkp_prk" ikm)
           for counter from 0 upto 254
-          for bytes = (LabeledExpand dkp_prk (ASCII "candidate")
-                                     (I2OSP counter 1) *Nsk*)
+          for bytes
+            = (labeled-expand dkp_prk "candidate" (I2OSP counter 1) *Nsk*)
           for sk = (progn
                      (setf (aref bytes 0) (logand (aref bytes 0) *bitmask*))
                      (OS2IP bytes))
           when (not (= sk 0)) return (values sk (EC-Scalar-Base-Mult sk))))
   (defun KEM-Encap (pkR)
-    (multiple-value-bind (skE pkE) (GenerateKeyPair)
+    (multiple-value-bind (skE pkE) (generate-key-pair)
       (let* ((dh (ECDH-Create-Shared-Secret skE pkR))
-             (enc (SerializePublicKey pkE))
-             (pkRm (SerializePublicKey pkR))
+             (enc (serialize-public-key pkE))
+             (pkRm (serialize-public-key pkR))
              (kem_context (|| enc pkRm))
-             (shared_secret (ExtractAndExpand dh kem_context)))
+             (shared_secret (extract-and-expand dh kem_context)))
         (values shared_secret enc))))
   (defun KEM-Decap (enc skR)
-    (let* ((pkE (DeserializePublicKey enc))
+    (let* ((pkE (deserialize-public-key enc))
            (dh (ECDH-Create-Shared-Secret skR pkE))
-           (pkRm (SerializePublicKey (EC-Scalar-Base-Mult skR)))
+           (pkRm (serialize-public-key (EC-Scalar-Base-Mult skR)))
            (kem_context (|| enc pkRm))
-           (shared_secret (ExtractAndExpand dh kem_context)))
+           (shared_secret (extract-and-expand dh kem_context)))
       shared_secret)))
 
 (defun Authenticate (sk_device reader_data bf)
@@ -129,12 +129,11 @@
   (cond ((null path) (values bf salt))
 	((typep (car path) 'number)
 	 (multiple-value-bind (bf-prime salt) (HDK salt (car path))
-	   (if (null bf) (fold salt (cdr path) bf-prime)
-	       (fold salt (cdr path)
-		     (BL-Combine-Blinding-Factors bf bf-prime)))))
-	(t (multiple-value-bind (sk pk) (KEM-Derive-Key-Pair salt)
-             (declare (ignore pk))
-             (fold (KEM-Decap (car path) sk) (cdr path) bf)))))
+           (fold salt (cdr path)
+                 (if (null bf) bf-prime
+                     (BL-Combine-Blinding-Factors bf bf-prime)))))
+	(t (fold (KEM-Decap (car path) (KEM-Derive-Key-Pair salt)) (cdr path)
+                 bf))))
 
 (defclass document () ((pk :reader pk :initarg :pk)))
 (defun make-document (doc salt index)