mirror of
git://git.gnupg.org/gnupg.git
synced 2024-09-06 12:46:22 +02:00
177 lines
4.5 KiB
Plaintext
177 lines
4.5 KiB
Plaintext
A Hacker's Guide to GNUPG
|
|
================================
|
|
(Some notes on GNUPG internals.)
|
|
|
|
|
|
===> Under construction <=======
|
|
|
|
|
|
RFCs
|
|
====
|
|
|
|
1423 Privacy Enhancement for Internet Electronic Mail:
|
|
Part III: Algorithms, Modes, and Identifiers.
|
|
|
|
1489 Registration of a Cyrillic Character Set.
|
|
|
|
1750 Randomness Recommendations for Security.
|
|
|
|
1991 PGP Message Exchange Formats.
|
|
|
|
2015 MIME Security with Pretty Good Privacy (PGP).
|
|
|
|
2144 The CAST-128 Encryption Algorithm.
|
|
|
|
2279 UTF-8, a transformation format of ISO 10646.
|
|
|
|
2440 OpenPGP.
|
|
|
|
|
|
|
|
Directory Layout
|
|
----------------
|
|
./ Readme, configure
|
|
./agent Gpg-agent and related tools
|
|
./doc Documentation
|
|
./doc Documentation
|
|
./g10 Gpg program here called gpg2
|
|
./jnlib Utility functions
|
|
./kbx Keybox library
|
|
./scd Smartcard daemon
|
|
./scripts Scripts needed by configure and others
|
|
./sm Gpgsm program
|
|
|
|
|
|
Detailed Roadmap
|
|
----------------
|
|
g10/gpg.c Main module with option parsing and all the stuff you have
|
|
to do on startup. Also has the exout handler and some
|
|
helper functions.
|
|
g10/sign.c Create signature and optionally encrypt
|
|
|
|
g10/parse-packet.c
|
|
g10/build-packet.c
|
|
g10/free-packet.c
|
|
Parsing and creating of OpenPGP message packets.
|
|
|
|
g10/getkey.c Key selection code
|
|
g10/pkclist.c Build a list of public keys
|
|
g10/skclist.c Build a list of secret keys
|
|
g10/ringedit.c Keyring I/O
|
|
g10/keydb.h
|
|
|
|
g10/keyid.c Helper functions to get the keyid, fingerprint etc.
|
|
|
|
|
|
g10/trustdb.c
|
|
g10/trustdb.h
|
|
g10/tdbdump.c
|
|
Management of the trustdb.gpg
|
|
|
|
g10/compress.c Filter to handle compression
|
|
g10/filter.h Declarations for all filter functions
|
|
g10/delkey.c Delete a key
|
|
g10/kbnode.c Helper for the KBNODE linked list
|
|
g10/main.h Prototypes and some constants
|
|
g10/mainproc.c Message processing
|
|
g10/armor.c Ascii armor filter
|
|
g10/mdfilter.c Filter to calculate hashs
|
|
g10/textfilter.c Filter to handle CR/LF and trailing white space
|
|
g10/cipher.c En-/Decryption filter
|
|
g10/misc.c Utlity functions
|
|
g10/options.h Structure with all the command line options
|
|
and related constants
|
|
g10/openfile.c Create/Open Files
|
|
g10/tdbio.c I/O handling for the trustdb.gpg
|
|
g10/tdbio.h
|
|
g10/hkp.h Keyserver access
|
|
g10/hkp.c
|
|
g10/packet.h Defintion of OpenPGP structures.
|
|
g10/passphrase.c Passphrase handling code
|
|
g10/pubkey-enc.c
|
|
g10/seckey-cert.c
|
|
g10/seskey.c
|
|
g10/import.c
|
|
g10/export.c
|
|
g10/comment.c
|
|
g10/status.c
|
|
g10/status.h
|
|
g10/sign.c
|
|
g10/plaintext.c
|
|
g10/encr-data.c
|
|
g10/encode.c
|
|
g10/revoke.c
|
|
g10/keylist.c
|
|
g10/sig-check.c
|
|
g10/signal.c
|
|
g10/helptext.c
|
|
g10/verify.c
|
|
g10/decrypt.c
|
|
g10/keyedit.c
|
|
g10/dearmor.c
|
|
g10/keygen.c
|
|
|
|
|
|
|
|
Memory allocation
|
|
-----------------
|
|
Use only the functions:
|
|
|
|
xmalloc
|
|
xmalloc_secure
|
|
xtrymalloc
|
|
xtrymalloc_secure
|
|
xcalloc
|
|
xcalloc_secure
|
|
xtrycalloc
|
|
xtrycalloc_secure
|
|
xrealloc
|
|
xtryrealloc
|
|
xstrdup
|
|
xtrystrdup
|
|
xfree
|
|
|
|
|
|
The *secure versions allocated memory in the secure memory. That is,
|
|
swapping out of this memory is avoided and is gets overwritten on
|
|
free. Use this for passphrases, session keys and other sensitive
|
|
material. This memory set aside for secure memory is linited to a few
|
|
k. In general the function don't print a memeory message and
|
|
terminate the process if there is not enough memory available. The
|
|
"try" versions of the functions return NULL instead.
|
|
|
|
|
|
Logging
|
|
-------
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Option parsing
|
|
---------------
|
|
GNUPG does not use getopt or GNU getopt but functions of it's own. See
|
|
util/argparse.c for details. The advantage of these functions is that
|
|
it is more easy to display and maintain the help texts for the options.
|
|
The same option table is also used to parse resource files.
|
|
|
|
|
|
|
|
What is an IOBUF
|
|
----------------
|
|
This is the data structure used for most I/O of gnupg. It is similar
|
|
to System V Streams but much simpler. Because OpenPGP messages are nested
|
|
in different ways; the use of such a system has big advantages. Here is
|
|
an example, how it works: If the parser sees a packet header with a partial
|
|
length, it pushes the block_filter onto the IOBUF to handle these partial
|
|
length packets: from now on you don't have to worry about this. When it sees
|
|
a compressed packet it pushes the uncompress filter and the next read byte
|
|
is one which has already been uncompressed by this filter. Same goes for
|
|
enciphered packet, plaintext packets and so on. The file g10/encode.c
|
|
might be a good staring point to see how it is used - actually this is
|
|
the other way: constructing messages using pushed filters but it may be
|
|
easier to understand.
|
|
|
|
|