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+;;; pgg-parse.el --- OpenPGP packet parsing
+
+;; Copyright (C) 1999, 2003 Free Software Foundation, Inc.
+
+;; Author: Daiki Ueno <[email protected]>
+;; Created: 1999/10/28
+;; Keywords: PGP, OpenPGP, GnuPG
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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, or (at your option)
+;; any later version.
+
+;; GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+
+;;    This module is based on
+
+;;	[OpenPGP] RFC 2440: "OpenPGP Message Format"
+;;	    by John W. Noerenberg, II <[email protected]>,
+;;          Jon Callas <[email protected]>, Lutz Donnerhacke <[email protected]>,
+;;          Hal Finney <[email protected]> and Rodney Thayer <[email protected]>
+;;	    (1998/11)
+
+;;; Code:
+
+(eval-when-compile (require 'cl))
+
+(require 'custom)
+
+(defgroup pgg-parse ()
+  "OpenPGP packet parsing"
+  :group 'pgg)
+
+(defcustom pgg-parse-public-key-algorithm-alist
+  '((1 . RSA) (2 . RSA-E) (3 . RSA-S) (16 . ELG-E) (17 . DSA) (20 . ELG))
+  "Alist of the assigned number to the public key algorithm."
+  :group 'pgg-parse
+  :type '(repeat
+	  (cons (sexp :tag "Number") (sexp :tag "Type"))))
+
+(defcustom pgg-parse-symmetric-key-algorithm-alist
+  '((1 . IDEA) (2 . 3DES) (4 . CAST5) (5 . SAFER-SK128))
+  "Alist of the assigned number to the simmetric key algorithm."
+  :group 'pgg-parse
+  :type '(repeat
+	  (cons (sexp :tag "Number") (sexp :tag "Type"))))
+
+(defcustom pgg-parse-hash-algorithm-alist
+  '((1 . MD5) (2 . SHA1) (3 . RIPEMD160) (5 . MD2))
+  "Alist of the assigned number to the cryptographic hash algorithm."
+  :group 'pgg-parse
+  :type '(repeat
+	  (cons (sexp :tag "Number") (sexp :tag "Type"))))
+
+(defcustom pgg-parse-compression-algorithm-alist
+  '((0 . nil); Uncompressed
+    (1 . ZIP)
+    (2 . ZLIB))
+  "Alist of the assigned number to the compression algorithm."
+  :group 'pgg-parse
+  :type '(repeat
+	  (cons (sexp :tag "Number") (sexp :tag "Type"))))
+
+(defcustom pgg-parse-signature-type-alist
+  '((0 . "Signature of a binary document")
+    (1 . "Signature of a canonical text document")
+    (2 . "Standalone signature")
+    (16 . "Generic certification of a User ID and Public Key packet")
+    (17 . "Persona certification of a User ID and Public Key packet")
+    (18 . "Casual certification of a User ID and Public Key packet")
+    (19 . "Positive certification of a User ID and Public Key packet")
+    (24 . "Subkey Binding Signature")
+    (31 . "Signature directly on a key")
+    (32 . "Key revocation signature")
+    (40 . "Subkey revocation signature")
+    (48 . "Certification revocation signature")
+    (64 . "Timestamp signature."))
+  "Alist of the assigned number to the signature type."
+  :group 'pgg-parse
+  :type '(repeat
+	  (cons (sexp :tag "Number") (sexp :tag "Type"))))
+
+(defcustom pgg-ignore-packet-checksum t; XXX
+  "If non-nil checksum of each ascii armored packet will be ignored."
+  :group 'pgg-parse
+  :type 'boolean)
+
+(defvar pgg-armor-header-lines
+  '("^-----BEGIN PGP MESSAGE\\(, PART [0-9]+\\(/[0-9]+\\)?\\)?-----\r?$"
+    "^-----BEGIN PGP PUBLIC KEY BLOCK-----\r?$"
+    "^-----BEGIN PGP PRIVATE KEY BLOCK-----\r?$"
+    "^-----BEGIN PGP SIGNATURE-----\r?$")
+  "Armor headers.")
+
+(eval-and-compile
+  (defalias 'pgg-char-int (if (fboundp 'char-int)
+			      'char-int
+			    'identity)))
+
+(defmacro pgg-format-key-identifier (string)
+  `(mapconcat (lambda (c) (format "%02X" (pgg-char-int c)))
+	      ,string "")
+  ;; `(upcase (apply #'format "%02x%02x%02x%02x%02x%02x%02x%02x"
+  ;;                 (string-to-int-list ,string)))
+  )
+
+(defmacro pgg-parse-time-field (bytes)
+  `(list (logior (lsh (car ,bytes) 8)
+		 (nth 1 ,bytes))
+	 (logior (lsh (nth 2 ,bytes) 8)
+		 (nth 3 ,bytes))
+	 0))
+
+(defmacro pgg-byte-after (&optional pos)
+  `(pgg-char-int (char-after ,(or pos `(point)))))
+
+(defmacro pgg-read-byte ()
+  `(pgg-char-int (char-after (prog1 (point) (forward-char)))))
+
+(defmacro pgg-read-bytes-string (nbytes)
+  `(buffer-substring
+    (point) (prog1 (+ ,nbytes (point))
+	      (forward-char ,nbytes))))
+
+(defmacro pgg-read-bytes (nbytes)
+  `(mapcar #'pgg-char-int (pgg-read-bytes-string ,nbytes))
+  ;; `(string-to-int-list (pgg-read-bytes-string ,nbytes))
+  )
+
+(defmacro pgg-read-body-string (ptag)
+  `(if (nth 1 ,ptag)
+       (pgg-read-bytes-string (nth 1 ,ptag))
+     (pgg-read-bytes-string (- (point-max) (point)))))
+
+(defmacro pgg-read-body (ptag)
+  `(mapcar #'pgg-char-int (pgg-read-body-string ,ptag))
+  ;; `(string-to-int-list (pgg-read-body-string ,ptag))
+  )
+
+(defalias 'pgg-skip-bytes 'forward-char)
+
+(defmacro pgg-skip-header (ptag)
+  `(pgg-skip-bytes (nth 2 ,ptag)))
+
+(defmacro pgg-skip-body (ptag)
+  `(pgg-skip-bytes (nth 1 ,ptag)))
+
+(defmacro pgg-set-alist (alist key value)
+  `(setq ,alist (nconc ,alist (list (cons ,key ,value)))))
+
+(when (fboundp 'define-ccl-program)
+
+  (define-ccl-program pgg-parse-crc24
+    '(1
+      ((loop
+	(read r0) (r1 ^= r0) (r2 ^= 0)
+	(r5 = 0)
+	(loop
+	 (r1 <<= 1)
+	 (r1 += ((r2 >> 15) & 1))
+	 (r2 <<= 1)
+	 (if (r1 & 256)
+	     ((r1 ^= 390) (r2 ^= 19707)))
+	 (if (r5 < 7)
+	     ((r5 += 1)
+	      (repeat))))
+	(repeat)))))
+
+  (defun pgg-parse-crc24-string (string)
+    (let ((h (vector nil 183 1230 nil nil nil nil nil nil)))
+      (ccl-execute-on-string pgg-parse-crc24 h string)
+      (format "%c%c%c"
+	      (logand (aref h 1) 255)
+	      (logand (lsh (aref h 2) -8) 255)
+	      (logand (aref h 2) 255)))))
+
+(defmacro pgg-parse-length-type (c)
+  `(cond
+    ((< ,c 192) (cons ,c 1))
+    ((< ,c 224)
+     (cons (+ (lsh (- ,c 192) 8)
+	      (pgg-byte-after (+ 2 (point)))
+	      192)
+	   2))
+    ((= ,c 255)
+     (cons (cons (logior (lsh (pgg-byte-after (+ 2 (point))) 8)
+			 (pgg-byte-after (+ 3 (point))))
+		 (logior (lsh (pgg-byte-after (+ 4 (point))) 8)
+			 (pgg-byte-after (+ 5 (point)))))
+	   5))
+    (t;partial body length
+     '(0 . 0))))
+
+(defun pgg-parse-packet-header ()
+  (let ((ptag (pgg-byte-after))
+	length-type content-tag packet-bytes header-bytes)
+    (if (zerop (logand 64 ptag));Old format
+	(progn
+	  (setq length-type (logand ptag 3)
+		length-type (if (= 3 length-type) 0 (lsh 1 length-type))
+		content-tag (logand 15 (lsh ptag -2))
+		packet-bytes 0
+		header-bytes (1+ length-type))
+	  (dotimes (i length-type)
+	    (setq packet-bytes
+		  (logior (lsh packet-bytes 8)
+			  (pgg-byte-after (+ 1 i (point)))))))
+      (setq content-tag (logand 63 ptag)
+	    length-type (pgg-parse-length-type
+			 (pgg-byte-after (1+ (point))))
+	    packet-bytes (car length-type)
+	    header-bytes (1+ (cdr length-type))))
+    (list content-tag packet-bytes header-bytes)))
+
+(defun pgg-parse-packet (ptag)
+  (case (car ptag)
+    (1 ;Public-Key Encrypted Session Key Packet
+     (pgg-parse-public-key-encrypted-session-key-packet ptag))
+    (2 ;Signature Packet
+     (pgg-parse-signature-packet ptag))
+    (3 ;Symmetric-Key Encrypted Session Key Packet
+     (pgg-parse-symmetric-key-encrypted-session-key-packet ptag))
+    ;; 4        -- One-Pass Signature Packet
+    ;; 5        -- Secret Key Packet
+    (6 ;Public Key Packet
+     (pgg-parse-public-key-packet ptag))
+    ;; 7        -- Secret Subkey Packet
+    ;; 8        -- Compressed Data Packet
+    (9 ;Symmetrically Encrypted Data Packet
+     (pgg-read-body-string ptag))
+    (10 ;Marker Packet
+     (pgg-read-body-string ptag))
+    (11 ;Literal Data Packet
+     (pgg-read-body-string ptag))
+    ;; 12       -- Trust Packet
+    (13 ;User ID Packet
+     (pgg-read-body-string ptag))
+    ;; 14       -- Public Subkey Packet
+    ;; 60 .. 63 -- Private or Experimental Values
+    ))
+
+(defun pgg-parse-packets (&optional header-parser body-parser)
+  (let ((header-parser
+	 (or header-parser
+	     (function pgg-parse-packet-header)))
+	(body-parser
+	 (or body-parser
+	     (function pgg-parse-packet)))
+	result ptag)
+    (while (> (point-max) (1+ (point)))
+      (setq ptag (funcall header-parser))
+      (pgg-skip-header ptag)
+      (push (cons (car ptag)
+		  (save-excursion
+		    (funcall body-parser ptag)))
+	    result)
+      (if (zerop (nth 1 ptag))
+	  (goto-char (point-max))
+	(forward-char (nth 1 ptag))))
+    result))
+
+(defun pgg-parse-signature-subpacket-header ()
+  (let ((length-type (pgg-parse-length-type (pgg-byte-after))))
+    (list (pgg-byte-after (+ (cdr length-type) (point)))
+	  (1- (car length-type))
+	  (1+ (cdr length-type)))))
+
+(defun pgg-parse-signature-subpacket (ptag)
+  (case (car ptag)
+    (2 ;signature creation time
+     (cons 'creation-time
+	   (let ((bytes (pgg-read-bytes 4)))
+	     (pgg-parse-time-field bytes))))
+    (3 ;signature expiration time
+     (cons 'signature-expiry
+	   (let ((bytes (pgg-read-bytes 4)))
+	     (pgg-parse-time-field bytes))))
+    (4 ;exportable certification
+     (cons 'exportability (pgg-read-byte)))
+    (5 ;trust signature
+     (cons 'trust-level (pgg-read-byte)))
+    (6 ;regular expression
+     (cons 'regular-expression
+	   (pgg-read-body-string ptag)))
+    (7 ;revocable
+     (cons 'revocability (pgg-read-byte)))
+    (9 ;key expiration time
+     (cons 'key-expiry
+	   (let ((bytes (pgg-read-bytes 4)))
+	     (pgg-parse-time-field bytes))))
+    ;; 10 = placeholder for backward compatibility
+    (11 ;preferred symmetric algorithms
+     (cons 'preferred-symmetric-key-algorithm
+	   (cdr (assq (pgg-read-byte)
+		      pgg-parse-symmetric-key-algorithm-alist))))
+    (12 ;revocation key
+     )
+    (16 ;issuer key ID
+     (cons 'key-identifier
+	   (pgg-format-key-identifier (pgg-read-body-string ptag))))
+    (20 ;notation data
+     (pgg-skip-bytes 4)
+     (cons 'notation
+	   (let ((name-bytes (pgg-read-bytes 2))
+		 (value-bytes (pgg-read-bytes 2)))
+	     (cons (pgg-read-bytes-string
+		    (logior (lsh (car name-bytes) 8)
+			    (nth 1 name-bytes)))
+		   (pgg-read-bytes-string
+		    (logior (lsh (car value-bytes) 8)
+			    (nth 1 value-bytes)))))))
+    (21 ;preferred hash algorithms
+     (cons 'preferred-hash-algorithm
+	   (cdr (assq (pgg-read-byte)
+		      pgg-parse-hash-algorithm-alist))))
+    (22 ;preferred compression algorithms
+     (cons 'preferred-compression-algorithm
+	   (cdr (assq (pgg-read-byte)
+		      pgg-parse-compression-algorithm-alist))))
+    (23 ;key server preferences
+     (cons 'key-server-preferences
+	   (pgg-read-body ptag)))
+    (24 ;preferred key server
+     (cons 'preferred-key-server
+	   (pgg-read-body-string ptag)))
+    ;; 25 = primary user id
+    (26 ;policy URL
+     (cons 'policy-url (pgg-read-body-string ptag)))
+    ;; 27 = key flags
+    ;; 28 = signer's user id
+    ;; 29 = reason for revocation
+    ;; 100 to 110 = internal or user-defined
+    ))
+
+(defun pgg-parse-signature-packet (ptag)
+  (let* ((signature-version (pgg-byte-after))
+	 (result (list (cons 'version signature-version)))
+	 hashed-material field n)
+    (cond
+     ((= signature-version 3)
+      (pgg-skip-bytes 2)
+      (setq hashed-material (pgg-read-bytes 5))
+      (pgg-set-alist result
+		     'signature-type
+		     (cdr (assq (pop hashed-material)
+				pgg-parse-signature-type-alist)))
+      (pgg-set-alist result
+		     'creation-time
+		     (pgg-parse-time-field hashed-material))
+      (pgg-set-alist result
+		     'key-identifier
+		     (pgg-format-key-identifier
+		      (pgg-read-bytes-string 8)))
+      (pgg-set-alist result
+		     'public-key-algorithm (pgg-read-byte))
+      (pgg-set-alist result
+		     'hash-algorithm (pgg-read-byte)))
+     ((= signature-version 4)
+      (pgg-skip-bytes 1)
+      (pgg-set-alist result
+		     'signature-type
+		     (cdr (assq (pgg-read-byte)
+				pgg-parse-signature-type-alist)))
+      (pgg-set-alist result
+		     'public-key-algorithm
+		     (pgg-read-byte))
+      (pgg-set-alist result
+		     'hash-algorithm (pgg-read-byte))
+      (when (>= 10000 (setq n (pgg-read-bytes 2)
+			    n (logior (lsh (car n) 8)
+				      (nth 1 n))))
+	(save-restriction
+	  (narrow-to-region (point)(+ n (point)))
+	  (nconc result
+		 (mapcar (function cdr) ;remove packet types
+			 (pgg-parse-packets
+			  #'pgg-parse-signature-subpacket-header
+			  #'pgg-parse-signature-subpacket)))
+	  (goto-char (point-max))))
+      (when (>= 10000 (setq n (pgg-read-bytes 2)
+			    n (logior (lsh (car n) 8)
+				      (nth 1 n))))
+	(save-restriction
+	  (narrow-to-region (point)(+ n (point)))
+	  (nconc result
+		 (mapcar (function cdr) ;remove packet types
+			 (pgg-parse-packets
+			  #'pgg-parse-signature-subpacket-header
+			  #'pgg-parse-signature-subpacket)))))))
+
+    (setcdr (setq field (assq 'public-key-algorithm
+			      result))
+	    (cdr (assq (cdr field)
+		       pgg-parse-public-key-algorithm-alist)))
+    (setcdr (setq field (assq 'hash-algorithm
+			      result))
+	    (cdr (assq (cdr field)
+		       pgg-parse-hash-algorithm-alist)))
+    result))
+
+(defun pgg-parse-public-key-encrypted-session-key-packet (ptag)
+  (let (result)
+    (pgg-set-alist result
+		   'version (pgg-read-byte))
+    (pgg-set-alist result
+		   'key-identifier
+		   (pgg-format-key-identifier
+		    (pgg-read-bytes-string 8)))
+    (pgg-set-alist result
+		   'public-key-algorithm
+		   (cdr (assq (pgg-read-byte)
+			      pgg-parse-public-key-algorithm-alist)))
+    result))
+
+(defun pgg-parse-symmetric-key-encrypted-session-key-packet (ptag)
+  (let (result)
+    (pgg-set-alist result
+		   'version
+		   (pgg-read-byte))
+    (pgg-set-alist result
+		   'symmetric-key-algorithm
+		   (cdr (assq (pgg-read-byte)
+			      pgg-parse-symmetric-key-algorithm-alist)))
+    result))
+
+(defun pgg-parse-public-key-packet (ptag)
+  (let* ((key-version (pgg-read-byte))
+	 (result (list (cons 'version key-version)))
+	 field)
+    (cond
+     ((= 3 key-version)
+      (pgg-set-alist result
+		     'creation-time
+		     (let ((bytes (pgg-read-bytes 4)))
+		       (pgg-parse-time-field bytes)))
+      (pgg-set-alist result
+		     'key-expiry (pgg-read-bytes 2))
+      (pgg-set-alist result
+		     'public-key-algorithm (pgg-read-byte)))
+     ((= 4 key-version)
+      (pgg-set-alist result
+		     'creation-time
+		     (let ((bytes (pgg-read-bytes 4)))
+		       (pgg-parse-time-field bytes)))
+      (pgg-set-alist result
+		     'public-key-algorithm (pgg-read-byte))))
+
+    (setcdr (setq field (assq 'public-key-algorithm
+			      result))
+	    (cdr (assq (cdr field)
+		       pgg-parse-public-key-algorithm-alist)))
+    result))
+
+(defun pgg-decode-packets ()
+  (if (re-search-forward "^=\\([A-Za-z0-9+/]\\{4\\}\\)$" nil t)
+      (let ((p (match-beginning 0))
+	    (checksum (match-string 1)))
+	(delete-region p (point-max))
+	(if (ignore-errors (base64-decode-region (point-min) p))
+	    (or (not (fboundp 'pgg-parse-crc24-string))
+		pgg-ignore-packet-checksum
+		(string-equal (base64-encode-string (pgg-parse-crc24-string
+						     (buffer-string)))
+			      checksum)
+		(progn
+		  (message "PGP packet checksum does not match")
+		  nil))
+	  (message "PGP packet contain invalid base64")
+	  nil))
+    (message "PGP packet checksum not found")
+    nil))
+
+(defun pgg-decode-armor-region (start end)
+  (save-restriction
+    (narrow-to-region start end)
+    (goto-char (point-min))
+    (re-search-forward "^-+BEGIN PGP" nil t)
+    (delete-region (point-min)
+		   (and (search-forward "\n\n")
+			(match-end 0)))
+    (when (pgg-decode-packets)
+      (goto-char (point-min))
+      (pgg-parse-packets))))
+
+(defun pgg-parse-armor (string)
+  (with-temp-buffer
+    (buffer-disable-undo)
+    (if (fboundp 'set-buffer-multibyte)
+	(set-buffer-multibyte nil))
+    (insert string)
+    (pgg-decode-armor-region (point-min)(point))))
+
+(eval-and-compile
+  (defalias 'pgg-string-as-unibyte (if (fboundp 'string-as-unibyte)
+				       'string-as-unibyte
+				     'identity)))
+
+(defun pgg-parse-armor-region (start end)
+  (pgg-parse-armor (pgg-string-as-unibyte (buffer-substring start end))))
+
+(provide 'pgg-parse)
+
+;;; arch-tag: 16c2eb82-1313-4a7c-a70f-420709b5b43e
+;;; pgg-parse.el ends here