1 files changed, 62 insertions, 0 deletions
diff --git a/hmac.rkt b/hmac.rkt
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+#lang typed/racket
+;;; Copyright 2011, Matthias Andreas Benkard.
+;;;
+;;;-----------------------------------------------------------------------------
+;;; This program is free software: you can redistribute it and/or modify
+;;; it under the terms of the GNU Affero General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; This program is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU Affero General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Affero General Public License
+;;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+;;;-----------------------------------------------------------------------------
+;;;
+
+(require "util.rkt")
+
+(provide: [hmac ((Bytes -> Exact-Nonnegative-Integer)
+                 Exact-Nonnegative-Integer
+                 Exact-Nonnegative-Integer
+                 Bytes
+                 Bytes
+                 ->
+                 Exact-Nonnegative-Integer)])
+
+;; Example:
+;;
+;;  (hmac whirlpool 64 64 #"<secret key>" #"hello")
+;;
+(define (hmac hashfn blocksize hashsize key msg)
+  (let ([opad (make-bytes blocksize #x5c)]
+        [ipad (make-bytes blocksize #x36)]
+        [padded-key
+         (pad-bytes (if (> (bytes-length key) blocksize)
+                        (integer->bytes (hashfn key))
+                        key)
+                    blocksize
+                    #x0
+                    'left)])
+    (hashfn (bytes-append (integer->bytes/size
+                           (bitwise-xor (bytes->integer opad)
+                                        (bytes->integer key))
+                           blocksize)
+                          (integer->bytes/size
+                           (hashfn
+                            (bytes-append
+                             (integer->bytes/size
+                              (bitwise-xor (bytes->integer ipad)
+                                           (bytes->integer key))
+                              blocksize)
+                             msg))
+                           hashsize)))))
+
+#;
+(begin
+  (require "whirlpool.rkt")
+  (printf "~x~%" (hmac whirlpool 64 64 #"" #"")))
+