dnssec-keygen {-a algorithm} {-b keysize} {-n nametype} [-c class] [-e] [-f flag] [-g generator] [-h] [-k] [-p protocol] [-r randomdev] [-s strength] [-t type] [-v level] {name}
dnssec-keygen generates keys for DNSSEC (Secure DNS), as defined in RFC 2535 and RFC <TBA\>. 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 (RSA) or RSASHA1, DSA, DH (Diffie Hellman), or HMAC-MD5. These values are case insensitive.
Note 1: that for DNSSEC, RSASHA1 is a mandatory to implement algorithm, and DSA is recommended. For TSIG, HMAC-MD5 is mandatory.
Note 2: HMAC-MD5 and DH automatically set the -k flag.
Specifies the number of bits in the key. The choice of key size depends on the algorithm used. RSAMD5 / RSASHA1 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 (KEY/DNSKEY)), HOST or ENTITY (for a key associated with a host (KEY)), USER (for a key associated with a user(KEY)) or OTHER (DNSKEY). These values are case insensitive.
Indicates that the DNS record containing the key should have the specified class. If not specified, class IN is used.
If generating an RSAMD5/RSASHA1 key, use a large exponent.
Set the specified flag in the flag field of the KEY/DNSKEY record. The only recognized flag is KSK (Key Signing Key) DNSKEY.
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 dnssec-keygen.
Generate KEY records rather than DNSKEY records.
Sets the protocol value for the generated key. The protocol is a number between 0 and 255. The default is 3 (DNSSEC). 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 to dnssec-makekeyset.
nnnn is the key name.
aaa is the numeric representation of the algorithm.
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 key.
The .key file contains a DNS KEY record that can be inserted into a zone file (directly or with a $INCLUDE statement).
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 issued:
dnssec-keygen -a DSA -b 768 -n ZONE example.com
The command would print a string of the form:
Kexample.com.+003+26160
In this example, dnssec-keygen creates the files Kexample.com.+003+26160.key and Kexample.com.+003+26160.private