.TH PGP 1 "PGP Version 2.6"
.\" NAME should be all caps, SECTION should be 1-8, maybe w/ subsection
.\" other parms are allowed: see man(7), man(1)
.SH NAME
pgp \- Pretty Good Privacy encryption system
.\" denote multiple entry points thus; makewhatis(8) will catch them
.SH SYNOPSIS
.B pgp \fR[\fIoptions\fR] \fIpgpfile
.PP
.B pgp \-e \fR[\fIoptions\fR] \fIfile user\fR .\|.\|.
.PP
.SH DESCRIPTION
.B PGP
(Pretty Good Privacy) is a public key encryption package to
protect E-mail and data files. It lets you communicate securely with
people you've never met, with no secure channels needed for prior
exchange of keys. It's well featured and fast, with sophisticated
key management, digital signatures, data compression, and good
ergonomic design. If you really want to learn how to use it
properly, it's best to read the full documentation that comes with
the system, which is very complete. This is a "quick start" guide
and reference manual; it is necessarily incomplete, and assumes you
are already familiar with most of the basic concepts, including the
concepts behind public key cryptography.
.SS "Terminology"
.B user id\fR: an ascii string used
to identify a user. User IDs tend to
look like "John Q. Public <[email protected]>"; please try sticking to
that format. When giving a user id to PGP, you may specify any unique
(case-insensitive) substring. E.g. john, or jqp@xyz.
.B pass phrase\fR: the secret string used to conventionally encipher your
private key. It's important that this be kept secret.
.B keyring\fR: a file containing a set of public or secret keys. Default
names for public and secret rings are "pubring.pgp" and "secring.pgp"
respectively.
.B ascii armor\fR: the ascii radix 64 format PGP uses for transmitting
messages over channels like E-Mail; similar in concept to uuencoding.
.SS "Command summary"
To see a quick command usage summary for PGP, just type:
.br
.B pgp -h
To encrypt a plaintext file with the recipient's public key:
.br
.B pgp -e \fItextfile her_userid \fR...
To sign a plaintext file with your secret key:
.br
.B pgp -s \fItextfile \fR[\fB-u \fIyour_userid\fR]
To sign a plaintext file with your secret key, and then encrypt it
with the recipient's public key:
.br
.B pgp -es \fItextfile her_userid \fR...
[\fB-u \fIyour_userid\fR]
To create a signature certificate that is detached from the document:
.br
.B pgp -sb \fItextfile \fR[\fB-u \fIyour_userid\fR]
To encrypt a plaintext file with just conventional cryptography, type:
.br
.B pgp -c \fItextfile
To decrypt an encrypted file, or to check the signature integrity of a
signed file:
.br
.B pgp \fIciphertextfile \fR[\fB-o \fIplaintextfile\fR]
To see a quick summary of PGP's key-management commands, just type:
.br
.B pgp -k
To generate your own unique public/secret key pair:
.br
.B pgp -kg
To add a public or secret key file's contents to your public or
secret key ring:
.br
.B pgp -ka \fIkeyfile \fR[\fIkeyring\fR]
To remove a key from your public key ring:
.br
.B pgp -kr \fIuserid \fR[\fIkeyring\fR]
To extract (copy) a key from your public or secret key ring:
.br
.B pgp -kx\fR[\fBa\fR] \fIuserid keyfile \fR[\fIkeyring\fR]
To view the contents of your public key ring:
.br
.B pgp -kv\fR[\fBv\fR] [\fIuserid\fR] [\fIkeyring\fR]
To view the "fingerprint" of a public key, to help verify it over
the telephone with its owner:
.br
.B pgp -kvc \fR[\fIuserid\fR] [\fIkeyring\fR]
To view the contents and check the certifying signatures of your
public key ring:
.br
.B pgp -kc \fR[\fIuserid\fR] [\fIkeyring\fR]
To edit the pass phrase for or add a userid to your secret key:
.br
.B pgp -ke \fIuserid \fR[\fIkeyring\fR]
To edit the trust parameters for a public key:
.br
.B pgp -ke \fIuserid \fR[\fIkeyring\fR]
To remove a key or just a userid from your public key ring:
.br
.B pgp -kr \fIuserid \fR[\fIkeyring\fR]
To sign and certify someone else's public key on your public key ring:
.br
.B pgp -ks \fIher_userid \fR[\fB-u \fIyour_userid\fR] [\fIkeyring\fR]
To remove selected signatures from a userid on a keyring:
.br
.B pgp -krs \fIuserid \fR[\fIkeyring\fR]
Command options that can be used in combination with other command
options (sometimes even spelling interesting words):
To produce a ciphertext file in ASCII radix-64 format, just add the
-a option when encrypting or signing a message or extracting a key:
.br
.B pgp -sea \fItextfile her_userid
.br
.B pgp -kxa \fIuserid keyfile \fR[\fIkeyring\fR]
To wipe out the plaintext file after producing the ciphertext file,
just add the
.B -w
(wipe) option when encrypting or signing a message:
.br
.B pgp -sew \fImessage.txt her_userid
To specify that a plaintext file contains ASCII text, not binary, and
should be converted to recipient's local text line conventions, add
the
.B -t
(text) option to other options:
.br
.B pgp -seat \fImessage.txt her_userid
To view the decrypted plaintext output on your screen (like the
Unix-style "more" command), without writing it to a file, use
the
.B -m
(more) option while decrypting:
.br
.B pgp -m \fIciphertextfile
To specify that the recipient's decrypted plaintext will be shown
.B only
on her screen and cannot be saved to disk, add the
.B -m
option:
.br
.B pgp -steam \fImessage.txt her_userid
To recover the original plaintext filename while decrypting, add
the
.B -p
option:
.br
.B pgp -p \fIciphertextfile
To use a Unix-style filter mode, reading from standard input and
writing to standard output, add the
.B -f
option:
.br
.B pgp -feast \fIher_userid \fB<\fIinputfile \fB>\fIoutputfile
.SS "The Config File"
PGP uses a configuration database that is stored in the file
"config.txt"; please see the manual for complete details.
Blank lines and lines beginning with "#" are comments.
Options take string, numeric, or boolean values. The
boolean values are "on" and "off".
These options can also be specified on the command line,
using a syntax such as
.B +armor=on\fR.
Keywords can be abbreviated to unique prefixes. Keywords are not
case-sensitive. "=on" is assumed for boolean options if nothing
is specified. Some highlights:
.B MYNAME - Default User ID for
.B Making Signatures
Default setting: MYNAME = ""
The configuration parameter MYNAME specifies the default user ID to
use to select the secret key for making signatures. If MYNAME is not
defined, the most recent secret key you installed on your secret key
ring is used. The user may also override this setting by
specifying a user ID on the PGP command line with the
.B -u
option.
.B TEXTMODE - Assuming Plaintext is a
.B Text File
Default setting: TEXTMODE = off
The configuration parameter TEXTMODE is equivalent to the
.B -t
command line option. If enabled, it causes PGP to assume the plaintext
is a text file, not a binary file, and converts it to "canonical text"
before encrypting it. Canonical text has a carriage return and a
linefeed at the end of each line of text.
This mode is automatically turned off if PGP detects that the plaintext
file contains 8-bit binary data. Thus, it is safe to leave enabled at
all times.
.B ARMOR - Enable ASCII Armor Output
Default setting: ARMOR = off
The configuration parameter ARMOR is equivalent to the
.B -a
command line option. If enabled, it causes PGP to emit ciphertext or
keys in ASCII Radix-64 format suitable for transporting through E-mail
channels. Output files are named with the ".asc" extension.
If you tend to use PGP mostly for E-mail, it may be a good idea to
enable this parameter.
.B ARMORLINES - Size of ASCII Armor Multipart Files
Default setting: ARMORLINES = 720
For large ASCII armor files, PGP splits them into files named
".asc1", ".asc2", ".asc3", etc. so as not to
choke mailers, which typically starts to happen around 50,000
bytes. This specifies the number of (64-byte) lines to place in
each file. If set to 0, PGP will not split ASCII armor files.
.B CLEARSIG - Enable Clear-Signed Output
Default setting: CLEARSIG = on
Normally, a signed and ASCII-armored PGP message is gibberish,
even though the text is not encrypted. This prevents munging
by mailers, but requires PGP to simply read the message.
If CLEARSIG is enabled, then when signing and ASCII-armoring a text
file, PGP uses a different format that includes the plaintext in
human-readable form. Lines beginning with "-" are quoted with "\-\ ".
To cope with some of the stupider mailers in the world, lines beginning
with "From" are also quoted, and trailing whitespace on lines is
stripped. PGP will remove the quoting if you use it to decrypt the
message, but the trailing whitespace is not recovered. This is still
useful enough to be enabled by default.
.B ENCRYPTTOSELF - Add MYNAME to Recipients List
Default setting: ENCRYPTTOSELF = off
If this is emabled, MYNAME will be implcitly added to the list of
recipients for any message you encrypt with a public key. Since in
this case, MYNAME is looked up in the public keyring, it is important
that it unambiguously specify the right key.
.B LANGUAGE - Language To Use
Default setting: LANGUAGE = en
If you want to use a different language, and translations are in the
language.txt file, setting this option will cause PGP's messages to
appear in a different language. If a translation for a message is
not available, it appears in english.
If you look at the supplied language.txt file, the format should
be obvious.
.B CHARSET - Character Set
Default setting: CHARSET = noconv
PGP tries to translate all text-mode messages into the ISO Latin-1
alphabet, or the KOI-8 alphabet for cyrillic alphabets. This
setting indicates the native character set, so PGP can do the
translation. Options are noconv, latin1 or koi8, indicating that
no translation should be done; cp850, indicating that IBM PC code
page 850 mappings should be used; ascii, indicating that a minimal
ASCII subset should be used; and alt_codes, indicating that the
IBM PC alt codes should be used for the cyrillic alphabet.
.B KEEPBINARY - Preserve Intermediate .pgp File
Default setting: KEEPBINARY = off
If KEEPBINARY is enabled, then PGP will produce a .pgp file in addition
to a .asc file when ASCII armor is enabled.
.B TMP - Temporary file directory
Default setting: TMP = ""
PGP produces temporary files while decrypting a message.
This is the directory they are stored in. If not specified in the config
file, the environment variable TMP is used, or the current directory.
It helps security somewhat if this is not a publicly-readable directory.
A local file system is also a good idea.
.B COMPRESS - Compress Plaintext Before Encrypting
Default setting: COMPRESS = on
PGP usually compresses the plaintext before encrypting it, so it will
have less to encrypt and the file you send will be smaller. It also
makes cryptanalysis harder. This is usually only turned off for
debugging purposes.
.B PAGER - Select Shell Command to Display Pager Output
Default setting: PAGER = ""
If set, PGP uses this program to view files when the
.B -m
option is specified. By default, PGP uses a simple builtin pager.
.B SHOWPASS - Echo Pass Phrase During Entry
Default setting: SHOWPASS = off
If someone is unable to type a long pass phrase reliably without seeing it,
this can be turned on, at the cost of security.
.B INTERACTIVE - Prompt Before Adding Each Key
Default setting: INTERACTIVE = off
By default, when given a file containing new keys, PGP asks if you would
like to add them to your public key ring. Since adding keys does not
imply that you trust them, adding more just wakes up space. If this
option is set, PGP asks about each key in a key file.
.B VERBOSE - Level of Detail Printed
Default setting: VERBOSE = 1
When set to 0, PGP only prints messages that are necessary or indicate an
error. When set to 2, PGP prints a significant amount of debugging
information describing what it's doing. Values above 2 have no effect.
.B PUBRING - Public Key Ring Location
Default setting: PUBRING = $PGPPATH/pubring.pgp
This is the path name to the public key ring to use.
.B SECRING - Secret Key Ring Location
Default setting: SECRING = $PGPPATH/secring.pgp
This is the path name to the secret key ring to use.
.B BAKRING - Backup Secret Key Ring
Default setting: BAKRING = ""
If this is set, when checking your key ring (\fBpgp -kc\fR), PGP will
compare the normal secret key ring against the given backup
copy, usually kept on write-protected removable media. This
is to protect against wholesale modifications to your key rings
in a spoofing attack.
.B RANDSEED - Random Number Seed File
Default setting: RANDSEED = $PGPPATH/randseed.bin
This is the path to a random seed file which is part of PGP's
random number generation algorithm, used to generate session keys.
While PGP goes to great lengths to use every available source of
randomness in generating session keys, this file is part of the
process and protecting it from disclosure is desirable.
.B COMMENT - ASCII Armor Comment
Default setting: COMMENT = ""
If set to a non-empty string, the value of this variable is
printed in the header of ASCII armor files, preceded by "Comment: ".
.B PKCS_COMPAT - PKCS compatibility
Default setting: PKCS_COMPAT = 1
This flag is ignored by PGP 2.5; it is always taken as 1. If
set to 1, PGP pads message digests and session keys inside
RSA-encrypted integers according to RSA Data Security, Inc.'s
Public-Key Cryptography Standards. If set to 0, earlier versions
of PGP generated an old incompatible formats. Either was accepted.
The RSAREF public-key encryption routines used by PGP 2.5 are unable to
decode the old formats.
There are still many areas of incompatibility with the PKCS;
in future, higher values of this flag may enable more compatibility
features.
.SS "Key certification"
PGP employs a system where users specify trusted users who may sign
other people's public keys. It is important that you understand how
this mechanism works; a full description is in the manual.
.B Important\fR: The manual also describes how to generate and send a
"key compromise" certificate that tells readers that your private key
has been compromised. If your key has been compromised, please read
the manual section on key compromise certificates and how to create
them; the faster you send out a key compromise certificate, the smaller
the window of opportunity for "bad guys" to send forged messages.
.SS "Important Hints"
PGP automatically tries compressing your input file; there is little point
in precompressing input for transmission.
PGP "ascii armor" is only needed on the outer transmitted message; as
an example, if you are, say, sending a public key to someone else and
you are for some reason signing it, simply armor the outer message;
it's better to sign the binary form of the key.
.SS "Foreign Languages"
PGP is easily customized for foreign language help and error
messages; it has been translated into a number of non-english languages.
See the manual for details on the file "language.txt".
.SH ENVIRONMENT
PGP uses several special files for its purposes, such as your standard
key ring files "pubring.pgp" and "secring.pgp", the random number seed
file "randseed.bin", the PGP configuration file "config.txt", and the
foreign language string translation file "language.txt". These
special files can be kept in any directory, by setting the environment
variable "PGPPATH" to the desired pathname. If PGPPATH remains
undefined, these special files are assumed to be in the current
directory.
Normally, PGP prompts the user to type a pass phrase whenever PGP
needs a pass phrase to unlock a secret key. But it is possible to
store the pass phrase in an environment variable from your operating
system's command shell. The environment variable PGPPASS can be
used to hold the pass phrase that PGP attempts to use first. If
the pass phrase stored in PGPPASS is incorrect, PGP recovers by
prompting the user for the correct pass phrase. This dangerous
feature makes your life more convenient if you have to regularly deal
with a large number of incoming messages addressed to your secret key,
by eliminating the need for you to repeatedly type in your pass phrase
every time you run PGP.
.B This is a very dangerous feature\fR; on UNIX it
is trivial to read someone else's environment using the ps(1) command.
If you are contemplating using this feature, be sure to read the
sections "How to Protect Secret Keys from Disclosure" and "Exposure on
Multi-user Systems" in the full PGP manual.
If the environment variable PGPPASSFD is defined, it must have a numeric
value, which PGP uses as a file descriptor number to read a pass phrase
from. This is done before anything else, so it can be combined with
an input file on standard input. This is mainly for use by shell scripts,
since under Unix it is difficult to read the contents of other people's
pipes.
.SH "RETURN VALUE"
PGP returns a 0 to the shell on success, and a nonzero error code on
failure. See the source code for details on nonzero status return
values.
.SH FILES
.br
.nf
.\" set tabstop to longest possible filename
.ta \w'/usr/local/lib/pgp/language.txt'u
*.pgp ciphertext, signature, or key file
*.asc ascii armor file
/usr/local/lib/config.txt system-wide configuration file
$PGPPATH/config.txt per-user configuration file
$PGPPATH/pubring.pgp public key ring
$PGPPATH/secring.pgp secret key ring
$PGPPATH/randseed.bin random number seed file
/usr/local/lib/pgp/language.txt
$PGPPATH/language.txt foreign language translation file
/usr/local/lib/pgp/pgp.hlp
$PGPPATH/pgp/pgp.hlp online help text file
/usr/local/lib/pgp/pgpkey.hlp
$PGPPATH/pgp/pgpkey.hlp online key-management help text file
.SH NOTE
The manual is really good, and it's really important in the long run
that you read it. PGP may be an unpickable lock, but you have to
put in in the door properly to keep out intruders. So read the manual
and find out how!
.SH CAVEATS
It is impossible to overemphasize the importance of protecting your
secret key. Anyone gaining access to it can forge messages from you or
read mail addressed to you. Be very cautious in using PGP on any
multi-user unix system.
PGP is believed by its authors to be the most secure cryptographic
software available to the public when used as directed, but then again
everyone always claims their pet encryption system is secure. Read the
section in the manual on "Trusting Snake Oil" and the section on
"Vulnerabilities" for caveats.
.SH DIAGNOSTICS
Mostly self explanatory.
.SH BUGS
PGP was initially written for the PC, and behaves very PCish. In
particular, its automagic file selection, file extensions, and the
like all make it somewhat alien in the UNIX environment.
This man page needs to be updated to reflect all the latest features.
.SH AUTHORS
Originally written by Philip R. Zimmermann. Later augmented by a cast
of thousands.
.SH "LEGAL RESTRICTIONS"
For detailed information on PGP licensing, distribution, copyrights,
patents, trademarks, liability limitations, and export controls, see
the "Legal Issues" section in the "PGP User's Guide, Volume II:
Special Topics". In particular, PGP is export restricted by the Offices
of Defense Trade Controls and Munitions Control, U.S. Department of
State, and shall not be exported or reexported from the United States,
directly or indirectly, without obtaining a U.S. Department of State
License.
PGP uses a public key algorithm claimed by U.S. patent #4,405,829. The
exclusive rights to this patent are held by a California company called
Public Key Partners. This is explained in the PGP User's Guide, Volume II.
PGP itself is freeware, but it inherits certain encumbrances from its
use of RSAREF to perform public-key encryption.
Another fully licensed commercial PGP is available from ViaCrypt, 2104 West
Peoria Avenue, Phoenix, Arizona 85029, (602) 944-0773.
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