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See ChangeLog: Tue Apr 6 19:58:12 CEST 1999 Werner Koch

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Werner Koch 1999-04-06 18:04:55 +00:00
parent 88d44edc56
commit 1b9a820c19
12 changed files with 145 additions and 53 deletions
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51
doc/HACKING
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@ -33,6 +33,14 @@ by sending a mail with "subscribe" in the body to
Please run scripts/autogen.sh to create some required files.
RSYNC access
============
The FTP archive is also available by anonymous rsync. A daily snapshot
of the CVS head revision is also available. See rsync(1) and try
"rsync ftp.gnupg.org::" to see available resources.
RFCs
====
@ -86,8 +94,8 @@ Directory Layout
./cipher Cryptographic functions
./g10 GnuPG application
./tools Some helper and demo programs
./keybox The keybox library
./gcrypt Stuff needed to build libgcrypt
./keybox The keybox library (under construction)
./gcrypt Stuff needed to build libgcrypt (under construction)
@ -127,13 +135,20 @@ The same option table is also used to parse resource files.
What is an iobuf
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. It should be replaced by a cleaner
and faster implementation. We are doing to much copying and the semantics
of "filter" removing are not very clean. EOF handling is also a problem.
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.
How to use the message digest functions
@ -171,11 +186,33 @@ Both methods may be combined. [Please see the source for the real syntax]
How to use the cipher functions
-------------------------------
cipher/cipher.c implements the interface to symmetric encryption functions.
As usual you have a function to open a cipher (which returns a handle to be used
with all other functions), some functions to set the key and other stuff and
a encrypt and decrypt function which does the real work. YOu probably know
how to work with files - so it should really be easy to work with these
functions. Here is an example:
CIPHER_HANDLE hd;
hd = cipher_open( CIPHER_ALGO_TWOFISH, CIPHER_MODE_CFB, 0 );
if( !hd )
oops( use other funtion to check for the real error );
rc = cipher_setkey( hd, key256bit, 32 ) )
if( rc )
oops( weak key or something like this );
cipher_setiv( hd, some_IV_or_NULL_for_all_zeroes );
cipher_encrypt( hd, plain, cipher, size );
cipher_close( hd );
How to use the public key functions
-----------------------------------
cipher/pubkey.c implements the interface to asymmetric encryption and
signature functions. This is basically the same as with the symmetric
counterparts, but due to their nature it is a little bit more complicated.
[Give an example]