G10 - The GNU Encryption and Signing Tool ------------------------------------------ THIS IS VERSION IS ONLY A TEST VERSION ! YOU SHOULD NOT USE IT FOR OTHER PURPOSES THAN EVALUATING THE CURRENT CODE. * The data format may change in the next version! * Some features are not yet implemented I provide this version as a reality check to start discussion. Please subscribe to g10@net.lut.ac.uk by sending a mail with the word "subscribe" in the body to "g10-request@net.lut.ac.uk". See the file COPYING for copyright and warranty information. Due to the fact that G10 does not use use any patented algorithm, it cannot be compatible to old PGP versions, because those use IDEA (which is worldwide patented) and RSA (which is patented in the United States until Sep 20, 2000). I'm sorry about this, but this is the world we have created (e.g. by using proprietary software). Because the OpenPGP standard is still a draft, G10 is not yet compatible to it (or PGP 5) - but it will. The data structures used are compatible with PGP 2.x, so it can parse an list such files and PGP should be able to parse data created by G10 and complain about unsupported algorithms. The default algorithms used by G10 are ElGamal for public-key encryption and signing; Blowfish with a 160 bit key for protecting the secret-key components, conventional and session encryption; RIPE MD-160 to create message digest. DSA, SHA-1 and CAST are also implemented, but not used on default. I decided not to use DSA as default signing algorithm, because it allows only for 1024 bit keys and this may be not enough in a couple of years. Installation ------------ 1) "./configure" to enable the integrated malloc debugging stuff, use: "./configure --enable-m-debug" 2) "make" 3) "make install" 4) You end up with a binary "g10" in /usr/local/bin 5) create a directory ".g10" under your hoem directory ("mkdir ~/.g10") Key Generation -------------- g10 --gen-key This asks some questions and then starts key generation. To create good random numbers for prime number generation, it uses a /dev/random which will emit only bytes if the kernel can gather enough entropy. If you see no progress, you should start some other activities such as mouse moves, "find /" or using the keyboard (on another window). Because we have no hardware device to generate random we have to use this method. Key generation shows progress by printing different characters to stderr: "." Miller-Rabin test failed. "+" Miller-Rabin test succeeded. "!" Reloading the pool with fresh prime numbers "^" Checking a new value for the generator "~" Issued during generator checks "<" Size of one factor decreased ">" Size of one factor increased The prime number for ElGamal is generated this way: 1) Make a prime number q of 160, 200, 240 bits (depending on the keysize). 2) Select the length of the other prime factors to be at least the size of q and calculate the number of prime factors needed 3) Make a pool of prime number, each of the length determined in step 2 4) Get a new permutation out of the pool or continue with step 3 if we have tested all permutations. 5) Calculate a candidate prime p = 2 * q * p[1] * ... * p[n] + 1 6) Check that this prime has the correct length (this may change q if it seems not to be possible to make a prime of the desired length) 7) Check whether this is a prime using trial divisions and the Miller-Rabin test. 8) Continue with step 4 if we did not find a prime in step 7. 9) Find a generator for that prime. You can sign a key with this command: g10 --sign-key Donald This let you sign the key of "Donald" with your default userid. g10 --sign-key -u Karl -u Joe Donald This let you sign the key of of "Donald" with the userids of "Karl" and "Joe". All existing signatures are checked, if some are invalid, a menu is offered to delete some of them, and the you are asked for every user wether you want to sign this key. You may remove a signature at any time using the option "--edit-sig", which asks for the sigs to remove. Sign ---- g10 -s file This creates a file file.g10 which is compressed and has a signature attached. g10 -sa file Same as above, but file.g10 is ascii armored. g10 -s -o out file Creates a signature of file, but writes the output to the file "out". Encrypt ------- g10 -e -r heine file This encrypts files with the public key of "heine" and writes it to "file.g10" echo "hallo" | g10 -ea -r heine | mail heine Ditto, but encrypts "hallo\n" and mails it as ascii armored message. Sign and Encrypt ---------------- g10 -se -r heine file This encrypts files with the public key of "heine" and writes it to "file.g10" after signing it with the default user id. g10 -se -r heine -u Suttner file Ditto, but sign the file with the user id "Suttner" Batch mode ---------- If you use the option "--batch", G10 runs in non-interactive mode and never prompts for input data. This even does not allow to enter passphrase; until we have a better solution (something like ssh-agent), you can use the option "--passhrase-fd n", which works like PGPs PGPPASSFD. Batch mode also causes G10 to terminate as soon as a BAD signature is detected. Exit status ----------- G10 returns with an exit status of 1 if in batch mode and a bad signature has been detected or 2 or higher for all other errors. You should parse stderr to get detailed informations about the errors. Esoteric commands ----------------- g10 --list-packets datafile Use this to list the contents of a data file. If the file is encrypted you are asked for the passphrase, so that G10 is able to look at the inner structure of a encrypted packet. --quick-random Do not use the stroing random generator but a faster one. This can be used to generate keys for tests; those are marked as insecure. --list-trustdb List the contents of the trustdb in a human readable format --list-trustdb List the tree of certificates for the given usernames --list-trust-path depth username List the possible trust paths for the given username, up to the specified depth. If depth is negative, duplicate introducers are not listed, because those would increase the trust probabilty only minimal. (you must use the special option "--" to stop option parsing when using a negative number) --print-mds filenames List all available message digest values for the fiven filenames --gen-prime n Generate and print a simple prime number of size n --gen-prime n q Generate a prime number suitable for ElGamal signatures of size n with a q as largest primefactor of n-1. --gen-prime n q 1 Ditto, but calculate a generator too. For more options/commands see the file g10/OPTIONS. Debug Flags ----------- Use the option "--debug n" to output debug informations. This option can be used multiple times, all values are ORed; n maybe prefixed with 0x to use hex-values. value used for ----- ---------------------------------------------- 1 packet reading/writing 2 MPI details 4 ciphers and primes (may reveal sensitive data) 8 iobuf filter functions 16 iobuf stuff 32 memory allocation stuff 64 caching 128 show memory statistics at exit 256 trust verification stuff Other Notes ----------- This is work in progress, so you may find duplicated code fragments, ugly data structures, weird usage of filenames and other thinks. I will run "indent" over the source when making a real distribution, but for now I stick to my own formatting rules. The primary FTP site is "ftp://ftp.guug.de/pub/gcrypt/" The primary WWW page is "http://www.d.shuttle.de/isil/g10.html" Please direct bug reports to or better post them to the mailing list .