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See ChangeLog: Wed Feb 10 17:15:39 CET 1999 Werner Koch

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Werner Koch 1999-02-10 16:22:40 +00:00
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8
doc/DETAILS
View file

@ -79,7 +79,7 @@ more arguments in future versions.
The used key has been revoked by his owner. No arguments yet.
BADARMOR
The ascii armor is corrupted. No arguments yet.
The ASCII armor is corrupted. No arguments yet.
RSA_OR_IDEA
The RSA or IDEA algorithms has been used in the data. A
@ -175,7 +175,7 @@ Record type 2: (directory record)
1 u32 cache record
1 byte ownertrust
1 byte dirflag
1 byte validity
1 byte validity of the key calucalted over all user ids
19 byte reserved
@ -208,7 +208,7 @@ Record type 4: (uid record)
1 u32 pointer to preference record
1 u32 siglist list of valid signatures
1 byte uidflags
1 byte reserved
1 byte validity of the key calculated over this user id
20 bytes ripemd160 hash of the username.
@ -418,7 +418,7 @@ Usage of gdbm files for keyrings
================================
The key to store the keyblock is it's fingerprint, other records
are used for secondary keys. fingerprints are always 20 bytes
where 16 bit fingerprints are appded with zero.
where 16 bit fingerprints are appended with zero.
The first byte of the key gives some information on the type of the
key.
1 = key is a 20 bit fingerprint (16 bytes fpr are padded with zeroes)

166
doc/FAQ
View file

@ -23,11 +23,10 @@
GNUPG is also useful for signing things. Things that are encrypted with
the secret key can be decrypted with the public key. To sign something, a
hash is taken of the data, and then the hash is in some form encoded
with the secret
key. If someone has your public key, they can verify that it is from
you and that it hasn't changed by checking the encoded form of the
hash with the public key.
hash is taken of the data, and then the hash is in some form encoded with
the secret key. If someone has your public key, they can verify that it
is from you and that it hasn't changed by checking the encoded form of
the hash with the public key.
A keyring is just a large file that stores keys. You have a public keyring
where you store yours and your friend's public keys. You have a secret
@ -63,12 +62,12 @@
or at a meeting of your local GNU/Linux User Group.
Hmm, what else. You may use the option "-o filename" to force output
to this filename (use "-" to force output to stdout).
"-r" just lets you specify the recipient (which public key you encrypt with)
on the command line instead of typing it interactively.
to this filename (use "-" to force output to stdout). "-r" just lets you
specify the recipient (which public key you encrypt with) on the command
line instead of typing it interactively.
Oh yeah, this is important. By default all data is encrypted in some weird
binary format. If you want to have things appear in ascii text that is
binary format. If you want to have things appear in ASCII text that is
readable, just add the '-a' option. But the preferred method is to use
a MIME aware mail reader (Mutt, Pine and many more).
@ -94,31 +93,31 @@
a v3 packet. GNUPG is the only program which had used
these v3 ElGamal keys - so this assumption is quite safe.
Q: Why is PGP 5.x not able to encrypt messages with my public key.
Q: Why is PGP 5.x not able to encrypt messages with my public key?
A: PGP Inc refuses to accept ElGamal keys of type 20 even for
encryption. They only supports type 16 (which are identical
at least for decryption). To be better interoperable, GNUPG
at least for decryption). To be more inter-operable, GNUPG
(starting with version 0.3.3) now also uses type 16 for the
ElGamal subkey which is created if the default key algorithm
is chosen. You may add an type 16 ElGamal key to your public
key which is easy as your key signatures are still valid.
Q: Why is PGP 5.x not able to verify my messages.
Q: Why is PGP 5.x not able to verify my messages?
A: PGP 5.x does not accept V4 signatures for data material but
OpenPGP requires generation of V3 signatures for all kind of
data. Use the option "--force-v3-sigs" to generate V3 signatures
for data.
Q: I can't delete an user id because it is already deleted on my
public keyring.
public keyring?
A: Because you can only select from the public key ring, there is
no direct way to do this. However it is not so complicated
do to it anyway: Create a new user id with exactly the same name,
you will notice that there are two identical user ids on the
secret ring now. Now select this user id and delete it; both
user ids from the secret ring will be removed.
no direct way to do this. However it is not very complicated
to do it anyway. Create a new user id with exactly the same name
and you will see that there are now two identical user ids on the
secret ring. Now select this user id and delete it. Both user
ids will be removed from the secret ring.
Q: How can I encrypt a message in way pgp 2.x is able to decrypt it later?
Q: How can I encrypt a message so that pgp 2.x is able to decrypt it?
A: You can't do that because pgp 2.x normally uses IDEA which is not
supported by GNUPG because it is patented, but if you have a modified
version of PGP you can try this:
@ -130,11 +129,11 @@
gpg -c --cipher-algo 3des --compress-algo 1 --no-comment myfile
You may replace "3des" by "cast5"; "blowfish" does not work with
You may replace "3des" by "cast5". "blowfish" does not work with
all versions of pgp5. You may also want to put
no-comment
compress-algo 1
into your ~/.gnupg/options file - this does not affect the normal
into your ~/.gnupg/options file - this does not affect normal
gnupg operation.
@ -142,42 +141,40 @@
A: The problem here is that we need a lot of random bytes and for that
we (on Linux the /dev/random device) must collect some random data.
It is really not easy to fill the Linux internal entropy buffer; I
talked to Ted Ts'o and he commited that the best way to fill the
buffer is to play with your keyboard.
Good security has it's price.
What I do is to hit several times on the shift,control, alternate,
capslock keys, as these keys do not produce any output to the screen.
This way you get your keys really fast (it's the same thing pgp2 does).
talked to Ted Ts'o and he commented that the best way to fill the buffer
is to play with your keyboard. Good security has it's price. What I do
is to hit several times on the shift, control, alternate, and capslock
keys, because these keys do not produce output to the screen. This way
you get your keys really fast (it's the same thing pgp2 does).
Another problem might be another program which eats up your random bytes
(a program (look at your daemons) that reads from /dev/[u]random).
Q: And it really takes long when I work on a remote system. Why?
A: Don't do this at all!
You should never create keys or even use gnupg on a remote system because
you normally have
no physical control over your secret keyring (which is in most cases
vulnerable to advanced dictionary attacks) - I strongly encourage
everyone to only create keys on a local computer (a disconnected
laptop is probably the best choice) and if you need it on your
connected box (I know: We all do this) be sure to have a strong
password for your account, your secret key and trust your Root.
A: Don't do this at all! You should never create keys or even use gnupg
on a remote system because you normally have no physical control over
your secret keyring (which is in most cases vulnerable to advanced
dictionary attacks) - I strongly encourage everyone to only create keys
on a local computer (a disconnected laptop is probably the best choice)
and if you need it on your connected box (I know: We all do this) be
sure to have a strong password for your account and for your secret key
and trust your Root.
When I check gnupg on a remote system via ssh (I have no Alpha here ;-)
I have the same problem too: it takes *very* long to create the keys,
so I use a special option --quick-random to generate insecure keys which are
only good for some tests.
I have the same problem. It takes a *very* long time to create the
keys, so I use a special option, --quick-random, to generate insecure
keys which are only good for some tests.
Q: How does the whole trust thing work?
A: It works more or less like PGP. The difference is, that the trust is
computed at the time it is needed; this is one of the reasons for the
A: It works more or less like PGP. The difference is that the trust is
computed at the time it is needed. This is one of the reasons for the
trustdb which holds a list of valid key signatures. If you are not
running in batch mode you will be asked to assign a trust parameter
(ownertrust) to a key. I have plans to use a cache for calculated
trust values to speed up calculation.
You can see the validity (calculated trust value) using this command:
You can see the validity (calculated trust value) using this command.
gpgm --list-keys --with-colons
@ -193,13 +190,13 @@
is only used for keys for which
the secret key is also available.
You can get a list of the assigned trust values (how far you trust
the owner to correctly sign another one's key)
You can get a list of the assigned trust values (how much you trust
the owner to correctly sign another person's key)
gpgm --list-ownertrust
The first field is the fingerprint of the primary key, the second one
the assigned value:
The first field is the fingerprint of the primary key, the second field
is the assigned value:
- = No Ownertrust value yet assigned.
n = Never trust this keyholder to correctly verify others signatures.
@ -207,42 +204,42 @@
f = Assume that the key holder really knows how to sign keys.
u = No need to trust ourself because we have the secret key.
Please keep these values confidential, as they express some opinions of
you about others. PGP does store these information with the keyring, so
it is not a good idea to publish the keyring instead of exporting the
keyring - gnupg stores the trust in the trust-DB and therefor it is okay
to give the keyring away (but we have a --export command too).
Keep these values confidential because they express your opinions
about others. PGP stores this information with the keyring thus
it is not a good idea to publish a PGP keyring instead of exporting the
keyring. gnupg stores the trust in the trust-DB so it is okay
to give a gpg keyring away (but we have a --export command too).
Q: What is the difference between options and commands?
A: If you do a "gpg --help", you will get two separate lists. The first is a list
of commands. The second is a list of options. Whenever you run GPG, you *must*
pick exactly one command (**with one exception, see below). You *may* pick one
or more options. The command should, just by convention, come at the end of the
argument list, after all the options. If the command takes a file (all the
basic ones do), the filename comes at the very end. So the basic way to
run gpg is:
A: If you do a "gpg --help", you will get two separate lists. The first is
a list of commands. The second is a list of options. Whenever you run GPG,
you *must* pick exactly one command (**with one exception, see below). You
*may* pick one or more options. The command should, just by convention,
come at the end of the argument list, after all the options. If the
command takes a file (all the basic ones do), the filename comes at the
very end. So the basic way to run gpg is:
gpg [--option something] [--option2] [--option3 something] --command file
Some options take arguments, for example the --output option (which can be
abbreviated -o) is an option which takes a filename. The option's argument
must follow immediately after the option itself: otherwise gpg doesn't know
abbreviated -o) is an option that takes a filename. The option's argument
must follow immediately after the option itself, otherwise gpg doesn't know
which option the argument is supposed to go with. As an option, --output and
its filename must come before the command. The --remote-user (-r) option takes
a name or keyid to encrypt the message to, which must come right after the -r
argument. The --encrypt (or -e) command comes after all the options, followed
by the file you wish to encrypt. So use:
argument. The --encrypt (or -e) command comes after all the options followed
by the file you wish to encrypt. So use
gpg -r alice -o secret.txt -e test.txt
If you write the options out in full, it is easier to read:
If you write the options out in full, it is easier to read
gpg --remote-user alice --output secret.txt --encrypt test.txt
If you're saving it in a file called ".txt" then you'd probably expect to see
ascii-armored text in there, so you need to add the --armor (-a) option,
which doesn't take any arguments:
ASCII-armored text in there, so you need to add the --armor (-a) option,
which doesn't take any arguments.
gpg --armor --remote-user alice --output secret.txt --encrypt test.txt
@ -251,7 +248,7 @@
gpg [--armor] [--remote-user alice] [--output secret.txt] --encrypt test.txt
The optional parts can be rearranged any way you want:
The optional parts can be rearranged any way you want.
gpg --output secret.txt --remote-user alice --armor --encrypt test.txt
@ -268,30 +265,30 @@
Q: What kind of output is this: "key C26EE891.298, uid 09FB: ...."?
A: This is the internal representation of an user id in the trustdb.
"C26EE891" is the keyid, "298" is the local id (a record number
in the trustdb) and "09FB" are the last two bytes of a ripe-md-160
in the trustdb) and "09FB" is the last two bytes of a ripe-md-160
hash of the user id for this key.
Q: What is trust, validity and ownertrust?
A: "ownertrust" is used instead of "trust" to make clear that
this is the value you have assigned to key to express, how far you
this is the value you have assigned to key to express how much you
trust the owner of this key to correctly sign (and so introduce)
other keys. "validity" or calculated trust is a value which
says, how far the gnupg thinks a key is valid (that it really belongs
other keys. "validity", or calculated trust, is a value which
says how much the gnupg thinks a key is valid (that it really belongs
to the one who claims to be the owner of the key).
For more see the chapter "The Web of Trust" in the
Manual [gpg: Oops: Internal error: manual not found - sorry]
Q: How do interpret some of the informational outputs:
A: While checking the validness of a key, GnuPG sometimes print
some informations which are prefixed with information about
the checked item:
Q: How do interpret some of the informational outputs?
A: While checking the validity of a key, GnuPG sometimes prints
some information which is prefixed with information about
the checked item.
"key 12345678.3456"
This is about the key with key ID 12345678 and the internal
number 3456, which is the record number of the so called
directory record in the trustdb.
"uid 12345678.3456/ACDE"
This is about the user ID for the same key; to identify the
This is about the user ID for the same key. To identify the
user ID the last two bytes of a ripe-md-160 over the user ID
ring is printed.
"sig 12345678.3456/ACDE/9A8B7C6D"
@ -302,15 +299,14 @@
Q: How do I sign a patch file?
A: Use "gpg --clearsign --not-dash-escaped ...".
The problem with --clearsign is
that all lines starting with a dash are quoted with "- "; obviously
diff produces many of lines starting with a dash and these are
then quoted and that is not good for patch ;-). In order to use
a patch file without removing the cleartext signature, the special
option --not-dash-escaped may be used to suppress generation of
these escape sequences. You should not mail such a patch because
spaces and line endings are also subject to the signature and a mailer
may not preserve these. If you want to mail a file you can simply sign
it using your MUA.
The problem with --clearsign is that all lines starting with a dash are
quoted with "- "; obviously diff produces many of lines starting with a
dash and these are then quoted and that is not good for patch ;-). To
use a patch file without removing the cleartext signature, the special
option --not-dash-escaped may be used to suppress generation of these
escape sequences. You should not mail such a patch because spaces and
line endings are also subject to the signature and a mailer may not
preserve these. If you want to mail a file you can simply sign it
using your MUA.

87
doc/gpg.1pod
View file

@ -67,7 +67,7 @@ B<-k> [I<username>] [I<keyring>]
Kludge to be somewhat compatible with PGP.
Without arguments, all public keyrings are listed.
With one argument, only I<keyring> is listed.
Special combinations are also allowed, but it may
Special combinations are also allowed, but they may
give strange results when combined with more options.
B<-kv> Same as B<-k>
B<-kvv> List the signatures with every key.
@ -130,7 +130,7 @@ B<--edit-key> I<name>
Remove a subkey.
B<expire>
Change the key expiration time. If a key is
select, the time of this key will be changed.
selected, the time of this key will be changed.
With no selection the key expiration of the
primary key is changed.
B<passwd>
@ -154,10 +154,10 @@ B<--edit-key> I<name>
key rings.
The listing shows you the key with its secondary
keys and all user ids. Selected keys or user ids
indicated by an asterisk. The trust value is
displayed with the primary key: The first one is the
assigned owner trust and the second the calculated
trust value; letters are used for the values:
are indicated by an asterisk. The trust value is
displayed with the primary key: the first is the
assigned owner trust and the second is the calculated
trust value. Letters are used for the values:
B<-> No ownertrust assigned / not yet calculated.
B<e> Trust calculation has failed.
B<q> Not enough information for calculation.
@ -201,11 +201,11 @@ B<--export-secret-keys> [I<names>]
B<--import>, B<--fast-import>
Import/merge keys. The fast version does not build
the trustdb; this can be deon at anytime with the
the trustdb; this can be done at any time with the
command B<--update-trustdb>.
B<--export-ownertrust>
List the assigned ownertrust values in ascii format
List the assigned ownertrust values in ASCII format
for backup purposes [B<gpgm> only].
B<--import-ownertrust> [I<filename>]
@ -215,9 +215,9 @@ B<--import-ownertrust> [I<filename>]
=head1 OPTIONS
Long options can be put in an options file (default F<~/.gnupg/options>);
do not write the 2 dashes, but simply the name of the option and any
arguments if required. Lines with a hash as the first non-white-space
Long options can be put in an options file (default F<~/.gnupg/options>).
Do not write the 2 dashes, but simply the name of the option and any
required arguments. Lines with a hash as the first non-white-space
character are ignored. Commands may be put in this file too, but that
does not make sense.
@ -250,7 +250,7 @@ B<--trusted-key> I<keyid>
You may also use this option to skip the verification
of your own secret keys which is normally done every
time GnuPG starts up: Use for I<keyid> the one of
time GnuPG starts up by using the I<keyid> of
your key.
B<-r> I<name>, B<--recipient> I<name>
@ -268,7 +268,7 @@ B<-q>, B<--quiet>
B<-z> I<n>
Set compress level to I<n>. A value of 0 for I<n>
disables compression. Default is to use the default
compression level of zlib (which is 6).
compression level of zlib (normally 6).
B<-t>, B<--textmode>
Use canonical text mode. If B<-t> (but not
@ -276,17 +276,17 @@ B<-t>, B<--textmode>
and signing, this enables clearsigned messages.
This kludge is needed for PGP compatibility;
normally you would use B<--sign> or B<--clearsign>
to selected the type os signatures.
to selected the type of the signature.
B<-n>, B<--dry-run>
Don't make any changes (not yet implemented).
B<--batch>
Batch mode; never ask, do not allow interactive
Use batch mode. Never ask, do not allow interactive
commands.
B<--no-batch>
Disable batch mode; this may be used if B<batch>
Disable batch mode. This may be used if B<batch>
is used in the options file.
B<--yes>
@ -297,7 +297,7 @@ B<--no>
B<--keyserver> I<name>
Use I<name> to lookup keys which are not yet in
your keyring; this is only done while verifying
your keyring. This is only done while verifying
messages with signatures. The option is also
required for the command B<--send-keys> to
specify the keyserver to where the keys should
@ -374,11 +374,11 @@ B<--set-filename> I<string>
B<--completes-needed> I<n>
Number of completely trusted users to introduce a new
key signator (defaults to 1).
key signer (defaults to 1).
B<--marginals-needed> I<n>
Number of marginally trusted users to introduce a new
key signator (defaults to 3)
key signer (defaults to 3)
B<--max-cert-depth> I<n>
Maximum depth of a certification chain (default is 5).
@ -409,7 +409,7 @@ B<--s2k-digest-algo> I<name>
encryption if B<--digest-algo> is not given.
B<--s2k-mode> I<number>
Selects how passphrases are mangled: A number of I<0>
Selects how passphrases are mangled. A number of I<0>
uses the plain passphrase (which is not recommended),
a I<1> (default) adds a salt to the passphrase and
I<3> iterates the whole process a couple of times.
@ -418,12 +418,12 @@ B<--s2k-mode> I<number>
B<--compress-algo> I<number>
Use compress algorithm I<number>. Default is I<2> which is
RFC1950 compression; you may use I<1> to use the old zlib
version which is used by PGP.
The default algorithm may give better
results because the window size is not limited to 8K.
If this is not used the OpenPGP behavior is used; i.e.
the compression algorithm is selected from the preferences.
RFC1950 compression. You may use I<1> to use the old zlib
version which is used by PGP. The default algorithm may
give better results because the window size is not limited
to 8K. If this is not used the OpenPGP behavior is used,
i.e. the compression algorithm is selected from the
preferences.
B<--digest-algo> I<name>
Use I<name> as message digest algorithm. Running the
@ -438,21 +438,20 @@ B<--throw-keyid>
process because all available secret keys are tried.
B<--not-dash-escaped>
This option changes the behavior of cleartext signature
This option changes the behavior of cleartext signatures
so that they can be used for patch files. You should not
send such an armored file via email because all spaces
and line endings are hashed too. You can not use this
option for data which has 5 dashes somewhere at the
beginning of a line - patch files don't have this.
A special armor header line tells GnuPG about this
cleartext signature framework.
option for data which has 5 dashes at the beginning of a
line, patch files don't have this. A special armor header
line tells GnuPG about this cleartext signature option.
B<--escape-from-lines>
Because some mailers change lines starting with "From "
to ">From " it is good to handle such lines in a special
way when creating cleartext signatures; all other PGP
versions do it this way too. Because this would violate
rfc2440, this option is not enabled per default.
way when creating cleartext signatures. All other PGP
versions do it this way too. This option is not enabled
by default because it would violate rfc2440.
B<--passphrase-fd> I<n>
Read the passphrase from file descriptor I<n>. If you use
@ -464,10 +463,10 @@ B<--rfc1991>
Try to be more RFC1991 (PGP 2.x) compliant.
B<--force-v3-sigs>
OpenPGP states that a implementation should generate
v4 signatures but PGP 5.x does only recognize such
signatures on key material. This options forces
v3 signatures for signatures on data.
OpenPGP states that an implementation should generate
v4 signatures but PGP 5.x recognizes v4 signatures only
on key material. This options forces v3 signatures for
signatures on data.
B<--lock-once>
Lock the file the first time a lock is requested
@ -510,7 +509,7 @@ B<-h>, B<--help>
=head1 RETURN VALUE
The Program returns 0 if everything was fine, 1 if at least
a signature was bad and other errorcode for fatal errors.
a signature was bad, and other error codes for fatal errors.
=head1 EXAMPLES
@ -552,15 +551,15 @@ Use a B<good> password for your user account and a B<good> passphrase
to protect your secret key. This passphrase is the weakest part of the
whole system. Programs to do dictionary attacks on your secret keyring
are very easy to write and so you should protect your B<~/.gnupg/>
directory very good.
directory very well.
Keep in mind that, if this program is used over a network (telnet), it
is B<very> easy to spy out your passphrase!
=head1 BUGS
On many systems this program should be installed as setuid(root); this
is necessary to lock some pages of memory. If you get no warning message
about insecure memory your OS kernel supports locking without being root;
setuid is dropped as soon as this memory is allocated.
On many systems this program should be installed as setuid(root). This
is necessary to lock memory pages. If you get no warning message about
insecure memory your OS kernel supports locking without being root.
The program drops root privileges as soon as locked memory is allocated.