;;;
;;; digest - abstract base class for message digest algorithms
;;;
;;;   Copyright (c) 2002-2003 Kimura Fuyuki, All rights reserved.
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;; An abstract base- and meta-class of message digest algorithms.
;; The concrete implementation is given in modules such as
;; rfc.md5 and rfc.sha1.

(define-module util.digest
  (export <message-digest-algorithm> <message-digest-algorithm-meta>
          digest-update! digest-final! digest digest-string
          digest-hexify)
  )
(select-module util.digest)

(define-class <message-digest-algorithm-meta> (<class>)
  ;; Block size (in bytes) used in HMAC, determined by each algorithm.
  ;; Older algorithms uses 64, while SHA-384/512 uses 128.
  ((hmac-block-size :init-keyword :hmac-block-size :init-value 64)))

(define-class <message-digest-algorithm> ()
  ()
  :metaclass <message-digest-algorithm-meta>)

(define-method digest-update! ((self <message-digest-algorithm>) data)
  #f)
(define-method digest-final! ((self <message-digest-algorithm>))
  #f)
(define-method digest ((class <message-digest-algorithm-meta>))
  #f)
(define-method digest-string ((class <message-digest-algorithm-meta>) string)
  (with-input-from-string string (cut digest class)))

;; utility
(define (digest-hexify string)
  (with-string-io string
    (cut generator-for-each (cut format #t "~2,'0x" <>) read-byte)))

