X-Git-Url: http://git.chise.org/gitweb/?a=blobdiff_plain;f=README;h=87854fc1dd0472e86301a5ed0086c661698a93f6;hb=74b46a0ecaa2cf2e877ae29ea9f4196f812688fd;hp=187db0d370eea27466b7151c501fe4d7a01fdecf;hpb=31d97193bafb50321267222e8e7db2489c4c43b0;p=elisp%2Fepg.git

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 * What's this?
 
-EasyPG is yet another GnuPG interface for Emacs.  It consists of a
-transparent file encryption application and easy-to-use elisp library
-to interact with GnuPG.
+EasyPG is yet another GnuPG interface for Emacs.  It consists of two
+parts:
+
+- "The EasyPG Assistant"
+  A GUI frontend of GnuPG
+- "The EasyPG Library"
+  A library to interact with GnuPG
+
+* Requirements
+
+** GNU Emacs 21.4 or XEmacs 21.4
+
+** GnuPG 1.4.3
 
 * Quick start
 
-(0) Put (require 'epg-file) in your ~/.emacs.el
+** Installation
+
+  $ ./configure
+  $ sudo make install
+
+Add the following line to your ~/.emacs
+
+  (require 'epa-setup)
+
+Then you can browse your keyring by `M-x epa-list-keys'.  In addition,
+you can do some cryptographic operations on dired.
+
+  M-x dired
+  (mark some files)
+  : e (or M-x epa-dired-do-encrypt)
+  (select recipients and click [OK])
+
+* Security
+
+There are security pitfalls around Emacs.
+
+** Passphrase may leak to a temporary file.
+
+The function call-process-region writes data in region to a temporary
+file. If your PGP library used this function, your passphrases would
+leak to the filesystem.
+
+The EasyPG Library does not use call-process-region to communicate
+with a gpg subprocess.
+
+** Passphrase may be stolen from a core file.
+
+If Emacs crashes and dumps core, Lisp strings in memory are also
+dumped within the core file. read-passwd function clears passphrase
+strings by (fillarray string 0) to avoid this risk. However, Emacs
+performs compaction in gc_sweep phase. If GC happens before fillarray,
+passphrase strings may be moved elsewhere in memory. Therefore,
+passphrase caching in elisp is generally a bad idea.
+
+The EasyPG Library dares to disable passphrase caching. Fortunately,
+there is more secure way to cache passphrases - use gpg-agent.
+
+* MUA Integration
 
-(1) Restart emacs
+The EasyPG Library can be used in combination with MUA (Mail User
+Agents).
 
-(2) C-x C-f ~/test.gpg
+** SEMI based MUA
 
-* Advantages over other competitors
+SEMI is the MIME library used by Wanderlust, cmail, T-gnus, etc.
 
-** EasyPG avoides potential security flaws of Emacs.
+There is an EasyPG capable SEMI library called EMIKO-EasyPG.  It can
+be downloaded from the same site of the EasyPG distribution point.
 
-*** `call-process-region' writes data in region to a temporary file.
-PGG and gpg.el use `call-process-region' to communicate with a
-subprocess "gpg".  So, your passphrases may leak to the filesystem.
+** PGG based MUA
 
-*** There is no way to clear strings safely.
-To prevent passphrases from been stealing from cores, `read-passwd'
-function clears passphrase strings by `(fillarray string 0)'.
-However, it is not enough.  In GC sweep phase, Emacs does compaction
-on small strings.  If GC happens before `fillarray', passphrase
-strings may be copied elsewhere in the memory.
+PGG is somewhat outdated PGP library used by Gnus, MH-E, etc.
 
-PGG and gpg.el enables passphrase caching by default.
+There is a PGG backend using EasyPG called pgg-epg.el.  However,
+pgg-epg.el provides no more additional features than pgg-gpg.el,
+because PGG's API is restricted so that it supports old PGP 2.x/5.x.