dnssec-keygen generates keys for DNSSEC
(Secure DNS), as defined in RFC 2535. It can also generate
keys for use with TSIG (Transaction Signatures), as
defined in RFC 2845.
Selects the cryptographic algorithm. The value of
algorithm must be one of RSAMD5 or RSA,
DSA, DH (Diffie Hellman), or HMAC-MD5. These values
are case insensitive.
Note that for DNSSEC, DSA is a mandatory to implement algorithm,
and RSA is recommended. For TSIG, HMAC-MD5 is mandatory.
Specifies the number of bits in the key. The choice of key
size depends on the algorithm used. RSA keys must be between
512 and 2048 bits. Diffie Hellman keys must be between
128 and 4096 bits. DSA keys must be between 512 and 1024
bits and an exact multiple of 64. HMAC-MD5 keys must be
between 1 and 512 bits.
Specifies the owner type of the key. The value of
nametype must either be ZONE (for a DNSSEC
zone key), HOST or ENTITY (for a key associated with a host),
or USER (for a key associated with a user). These values are
Indicates that the DNS record containing the key should have
the specified class. If not specified, class IN is used.
If generating an RSA key, use a large exponent.
If generating a Diffie Hellman key, use this generator.
Allowed values are 2 and 5. If no generator
is specified, a known prime from RFC 2539 will be used
if possible; otherwise the default is 2.
Prints a short summary of the options and arguments to
Sets the protocol value for the generated key. The protocol
is a number between 0 and 255. The default is 2 (email) for
keys of type USER and 3 (DNSSEC) for all other key types.
Other possible values for this argument are listed in
RFC 2535 and its successors.
Specifies the source of randomness. If the operating
system does not provide a /dev/random
or equivalent device, the default source of randomness
is keyboard input. randomdev specifies
the name of a character device or file containing random
data to be used instead of the default. The special value
keyboard indicates that keyboard
input should be used.
Specifies the strength value of the key. The strength is
a number between 0 and 15, and currently has no defined
purpose in DNSSEC.
Indicates the use of the key. type must be
one of AUTHCONF, NOAUTHCONF, NOAUTH, or NOCONF. The default
is AUTHCONF. AUTH refers to the ability to authenticate
data, and CONF the ability to encrypt data.
Sets the debugging level.
When dnssec-keygen completes successfully,
it prints a string of the form Knnnn.+aaa+iiiii
to the standard output. This is an identification string for
the key it has generated. These strings can be used as arguments
nnnn is the key name.
aaa is the numeric representation of the
iiiii is the key identifier (or footprint).
dnssec-keygen creates two file, with names based
on the printed string. Knnnn.+aaa+iiiii.key
contains the public key, and
Knnnn.+aaa+iiiii.private contains the private
The .key file contains a DNS KEY record that
can be inserted into a zone file (directly or with a $INCLUDE
The .private file contains algorithm specific
fields. For obvious security reasons, this file does not have
general read permission.
Both .key and .private
files are generated for symmetric encryption algorithm such as
HMAC-MD5, even though the public and private key are equivalent.
To generate a 768-bit DSA key for the domain
example.com, the following command would be
dnssec-keygen -a DSA -b 768 -n ZONE example.com
The command would print a string of the form:
In this example, dnssec-keygen creates
the files Kexample.com.+003+26160.key and