X-Git-Url: http://git.chise.org/gitweb/?a=blobdiff_plain;f=README;h=30f6f0102526367247b7ec6f054b4d99d834eff4;hb=24c376fab8b0785deeb6e1df796624a035090b20;hp=ffe7c594d8a702cde8a3790011c07a4a8ef144c1;hpb=2823337840bdb649749f2a7934072770885f526a;p=elisp%2Fepg.git

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 * What's this?
 
-EasyPG is yet another GnuPG interface for Emacs.  It consists of two
-parts: transparent file encryption utility and easy-to-use elisp
-library to interact with GnuPG.
+EasyPG is a GnuPG interface for Emacs.  It has two aspects: convenient
+tools which allow to use GnuPG from Emacs (EasyPG Assistant), and a
+fully functional interface library to GnuPG (EasyPG Library.)
+
+* 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 by 'm' and click [OK])
+
+* MUA Integration
+
+The EasyPG Library can be used in combination with various MUA (Mail
+User Agents.)
+
+** CVS version of Gnus
+
+CVS version of Gnus supports EasyPG natively, simply put the following
+line into your ~/.emacs.
+
+  (setq mml2015-use 'epg)
+
+Other options which affect on the binding are
+
+  mml2015-signers
+  mml2015-encrypt-to-self
+  mml2015-cache-passphrase
+  mml2015-passphrase-cache-expiry
+  mml2015-verbose
+
+NOTE: You need not to install pgg-epg.el in this case.
+
+** PGG based MUA
+
+PGG is somewhat outdated PGP library used by old Gnus, MH-E, etc.
+
+There is a PGG backend using EasyPG called pgg-epg.el.  However,
+EasyPG API is a superset of PGG, so pgg-epg.el just emulates the old
+behavior of pgg.el.  Major features which PGG lacks are
+
+- Key selection user interface
+- Diagnosis interface to the verify operation
+- Web of trust
+- S/MIME using gpgsm
+
+** SEMI based MUA
+
+SEMI is the MIME library used by Wanderlust, cmail, T-gnus, etc.
+
+There is an EasyPG capable SEMI library called EMIKO-EasyPG.  It can
+be downloaded from the same site of the EasyPG distribution point.
+
+* Security
+
+There are security pitfalls around Emacs.
 
-(1) Restart emacs
+** Passphrase may leak to a temporary file.
 
-(2) C-x C-f ~/test.gpg
+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.
 
-* Advantages over other competitors
+The EasyPG Library does not use call-process-region to communicate
+with a gpg subprocess.
 
-** EasyPG avoides potential security flaws of Emacs.
+** Passphrase may be stolen from a core file.
 
-*** `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.
+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.
 
-*** 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.  Emacs does compaction of small strings in
-GC sweep phase.  If GC happens before `fillarray', passphrase strings
-may be copied elsewhere in the memory.  PGG and gpg.el enables
-passphrase caching by default.
+The EasyPG Library dares to disable passphrase caching. Fortunately,
+there is more secure way to cache passphrases - use gpg-agent.