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Common Lisp implementation running on the JVM
;;; digest.lisp
;;;
;;; Copyright (C) 2012 Mark Evenson
;;; $Id$
;;; This program is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU General Public License
;;; as published by the Free Software Foundation; either version 2
;;; 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 General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program; if not, write to the Free Software
;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
;;;
;;; As a special exception, the copyright holders of this library give you
;;; permission to link this library with independent modules to produce an
;;; executable, regardless of the license terms of these independent
;;; modules, and to copy and distribute the resulting executable under
;;; terms of your choice, provided that you also meet, for each linked
;;; independent module, the terms and conditions of the license of that
;;; module. An independent module is a module which is not derived from
;;; or based on this library. If you modify this library, you may extend
;;; this exception to your version of the library, but you are not
;;; obligated to do so. If you do not wish to do so, delete this
;;; exception statement from your version.
(require :java)
(in-package :system)
(defun asciify (digest)
(format nil "~{~2,'0X~}"
(mapcar (lambda (b) (if (< b 0) (+ 256 b) b))
(java::list-from-jarray digest))))
;;;; Really needs to concatenate all input into a single source of
;;;; bytes, running digest over that concatentation.
(defun sha256 (&rest paths-or-strings) ;;; XXX more than one arg is very broken.
"Returned ASCIIfied representation of SHA256 digest of byte-based resource at PATHS-OR-STRINGs."
(unless (and (null (rest paths-or-strings))
(pathnamep (first paths-or-strings)))
(warn "Unaudited computation of cryptographic digest initiated.")) ;; TODO Need tests with some tool for verification
(let ((first (first paths-or-strings))
(rest (rest paths-or-strings)))
(concatenate 'string
(when first
(asciify
(typecase first
(pathname (digest first))
(string (digest first))
(null)
(list
(concatenate 'string
(sha256 (first first))
(sha256 (rest first)))))))
(when rest
(sha256 rest)))))
#+nil ;; Bugs out the compiler
(defun sha256 (paths-or-strings)
(labels ((walk (p-or-s)
((atom p-or-s)
(typecase p-or-s
(pathname
(digest-path p-or-s))
(string
(error "Somebody implement me please"))))
((cons p-or-s)
(walk (first p-or-s)
(rest p-or-s)))))
(concatenate 'string
(walk paths-or-strings))))
(defgeneric digest (resource &key (digest 'sha-256))
(:documentation "Digest byte based resource at RESOURCE."))
(defun digest-path (path) (asciify (digest path 'nio 'sha-256)))
(defvar *digest-types*
'((sha-1 . "SHA-1")
(sha-256 . "SHA-256")
(sha-512 . "SHA-512"))
"Normalization of cryptographic digest naming.")
;;; Implementation
(defconstant +byte-buffer-rewind+
(java:jmethod "java.nio.ByteBuffer" "rewind"))
(defconstant +byte-buffer-get+
(java:jmethod "java.nio.ByteBuffer" "get" "[B" "int" "int"))
(defconstant +digest-update+
(java:jmethod "java.security.MessageDigest" "update" "[B" "int" "int"))
(defmethod digest ((url pathname) &key (digest 'sha-256))
(digest-nio url :digest digest))
(defun digest-nio (source &key (digest 'sha-256))
"Calculate digest with default of :SHA-256 pathname specified by URL.
Returns an array of JVM primitive signed 8-bit bytes.
Uses \"New I/O\" in JVM \"worse named API of all time\".
*DIGEST-TYPES* controls the allowable digest types."
(let*
((channel (typecase source
(pathname
(java:jcall "getChannel" (java:jnew "java.io.FileInputStream"
(namestring source))))
(string
(java:jstatic "newChannel" "java.nio.channels.Channels"
(java:jnew "java.io.ByteArrayInputStream"
(java:jcall "getBytes" source))))
(error "Typecase failed of object of type ~S." source)))
(digest-type (cdr (assoc digest *digest-types*)))
(digest (java:jstatic "getInstance" "java.security.MessageDigest" digest-type))
(length 8192)
(buffer (java:jstatic "allocateDirect" "java.nio.ByteBuffer" length))
(array (java:jnew-array "byte" length)))
(do ((read (java:jcall "read" channel buffer)
(java:jcall "read" channel buffer)))
((not (> read 0)))
(java:jcall +byte-buffer-rewind+ buffer)
(java:jcall +byte-buffer-get+ buffer array 0 read)
(java:jcall +byte-buffer-rewind+ buffer)
(java:jcall +digest-update+ digest array 0 read))
(java:jcall "digest" digest)))
(defmethod digest ((source string) &key (digest 'sha-256))
(digest-nio source :digest digest))
(export 'sha256 :system)