path: root/doc/man/dnssec/dnssec-keygen.8

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.\" $Id: dnssec-keygen.8,v 1.11 2000/11/18 02:57:34 bwelling Exp $

.Dd Jun 30, 2000
.Dt DNSSEC-KEYGEN 8
.Os BIND9 9
.ds vT BIND9 Programmer's Manual
.Sh NAME
.Nm dnssec-keygen
.Nd key generation tool for DNSSEC
.Sh SYNOPSIS
.Nm dnssec-keygen
.Fl a Ar algorithm
.Fl b Ar keysize
.Op Fl c Ar class
.Op Fl e
.Op Fl g Ar generator
.Op Fl h
.Fl n Ar nametype
.Op Fl p Ar protocol-value
.Op Fl r Ar randomdev
.Op Fl s Ar strength-value
.Op Fl t Ar type
.Op Fl v Ar level
.Ar name
.Sh DESCRIPTION
.Nm dnssec-keygen
generates keys for DNSSEC, Secure DNS, as defined in RFC2535.
It also generates keys for use in Transaction Signatures, TSIG, which
is defined in RFC2845.
.Pp
A short summary of the options and arguments to
.Nm dnssec-keygen
is printed by the
.Fl h
(help) option.
.Pp
The
.Fl a ,
.Fl b ,
and
.Fl n
options and their arguments must be supplied when generating keys.
The domain name that the key has to be generated for is given by
.Ar name .
.Pp
The choice of encryption algorithm is selected by the
.Fl a
option to
.Nm dnssec-keygen .
.Ar algorithm
must be one of
.Dv RSAMD5 ,
.Dv DH ,
.Dv DSA
or
.Dv HMAC-MD5
to indicate that an RSA, Diffie-Hellman, Digital Signature
Algorithm or HMAC-MD5 key is required.
An argument of
.Dv RSA
can also be given, which is equivalent to
.Dv RSAMD5 .
The argument identifying the encryption algorithm is case-insensitive.
DNSSEC specifies DSA as a mandatory algorithm and RSA as a recommended one.
Implementations of TSIG must support HMAC-MD5.
.Pp
The number of bits in the key is determined by the
.Ar keysize
argument following the
.Fl b
option.
The choice of key size depends on the algorithm that is used.
RSA keys must be between 512 and 2048 bits.
Diffie-Hellman keys must be between 128 and 4096 bits.
For DSA, the key size must be between 512 and 1024 bits and a multiple
of 64.
The length of an HMAC-MD5 key can be between 1 and 512 bits.
.Pp
The
.Fl n
option specifies how the generated key will be used.
.Ar nametype
can be either
.Dv ZONE ,
.Dv HOST ,
.Dv ENTITY ,
or
.Dv USER
to indicate that the key will be used for signing a zone, host,
entity or user respectively.
In this context
.Dv HOST
and
.Dv ENTITY
are identical.
.Ar nametype
is case-insensitive.
.Pp
The
.Fl c
option specifies that the when creating a KEY record, the specified class
should be used instead of IN.
.Pp
The
.Fl e
option can only be used when generating RSA keys.
It tells
.Nm dnssec-keygen
to use a large exponent.
When creating Diffie-Hellman keys, the
.Fl g
option selects the Diffie-Hellman generator
.Ar generator
that is to be used.
The only supported values value of
.Ar generator
are 2 and 5.
If no Diffie-Hellman generator is supplied, a known prime
from RFC2539 will be used if possible; otherwise 2 will be used as the
generator.
.Pp
The
.Fl p
option sets the protocol value for the generated key to
.Ar protocol-value .
The default is 2 (email) for keys of type
.Dv USER
and 3 (DNSSEC) for all other key types.
Other possible values for this argument are listed in RFC2535 and its
successors.
.Pp
.Nm dnssec-keygen
uses random numbers to seed the process
of generating keys.
If the system does not have a
.Pa /dev/random
device that can be used for generating random numbers,
.Nm dnssec-keygen
will prompt for keyboard input and use the time intervals between
keystrokes to provide randomness.
The
.Fl r
option overrides this behaviour, making
.Nm dnssec-keygen
use
.Ar randomdev
as a source of random data.
.Pp
The key's strength value can be set with the
.Fl s
option.
The generated key will sign DNS resource records
with a strength value of
.Ar strength-value .
It should be a number between 0 and 15.
The default strength is zero.
The key strength field currently has no defined purpose in DNSSEC.
.Pp
The
.Fl t
option indicates if the key is to be used for authentication or
confidentiality.
.Ar type
can be one of
.Dv AUTHCONF ,
.Dv NOAUTHCONF ,
.Dv NOAUTH
or
.Dv NOCONF .
The default is
.Dv AUTHCONF .
If type is
.Dv AUTHCONF
the key can be used for authentication and confidentialty.
Setting
.Ar type
to
.Dv NOAUTHCONF
indicates that the key cannot be used for authentication or confidentialty.
A value of
.Dv NOAUTH
means the key can be used for confidentiality but not for
authentication.
Similarly,
.Dv NOCONF
defines that the key cannot be used for confidentiality though it can
be used for authentication.
.Pp
The
.Fl v
option can be used to make
.Nm dnssec-keygen
more verbose.
As the debugging/tracing level
.Ar level
increases,
.Nm dnssec-keygen
generates increasingly detailed reports about what it is doing.
The default level is zero.
.Sh GENERATED KEYS
When
.Nm dnssec-keygen
completes it prints a string of the form
.Ar Knnnn.+aaa+iiiii
on the standard output.
This is an identification string for the key it has generated.
These strings can be supplied as arguments to
.Xr dnssec-makekeyset 8 .
.Pp
The
.Ar nnnn.
part is the dot-terminated domain name given by
.Ar name .
The DNSSEC algorithm identifier is indicated by
.Ar aaa -
001 for RSA, 002 for Diffie-Hellman, 003 for DSA or 157 for HMAC-MD5.
.Ar iiiii
is a five-digit number identifying the key.
.Pp
.Nm dnssec-keygen
creates two files.
The file names are adapted from the key identification string above.
They have names of the form:
.Ar Knnnn.+aaa+iiiii.key
and
.Ar Knnnn.+aaa+iiiii.private .
These contain the public and private parts of the key respectively.
The files generated by
.Nm dnssec-keygen
obey this naming convention to
make it easy for the signing tool
.Xr dnssec-signzone 8
to identify which file(s) have to be read to find the necessary
key(s) for generating or validating signatures.
.Pp
The
.Ar .key
file contains a KEY resource record that can be inserted into a zone file
with a
.Dv $INCLUDE
statement.
The private part of the key is in the
.Ar .private
file.
It contains details of the encryption algorithm that was used and any
relevant parameters: prime number, exponent, modulus, subprime, etc.
For obvious security reasons, this file does not have general read
permission.
The private part of the key is used by
.Xr dnssec-signzone 8
to generate signatures and the public part is used to verify the
signatures.
Both
.Ar .key
and
.Ar .private
key files are generated for symmetric encryption algorithm such as
HMAC-MD5, even though the public and private key are equivalent.
.Sh EXAMPLE
To generate a 768-bit DSA key for the domain
.Dv example.com ,
the following command would be issued:
.Pp
.Dl # dnssec-keygen -a DSA -b 768 -n ZONE example.com
.Dl Kexample.com.+003+26160
.Pp
.Nm dnssec-keygen
has printed the key identification string
.Dv Kexample.com.+003+26160 ,
indicating a DSA key with identifier 26160.
It will also have created the files
.Pa Kexample.com.+003+26160.key
and
.Pa Kexample.com.+003+26160.private
containing respectively the public and private keys for the generated
DSA key.
.Sh FILES
.Pa /dev/random
.Sh SEE ALSO
.Xr RFC2535,
.Xr RFC2845,
.Xr RFC2539,
.Xr dnssec-makekeyset 8 ,
.Xr dnssec-signkey 8 ,
.Xr dnssec-signzone 8 .
.Sh BUGS
The naming convention for the public and private key files is a little
clumsy.
It won't work for domain names that are longer than 236 characters
because of the
.Ar .+aaa+iiiii.private
suffix results in filenames that are too long for most
.Ux
systems.