dnssec-keygen — DNSSEC key generation tool
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 ] {name}level
dnssec-keygen generates keys for DNSSEC (Secure DNS), as defined in RFC 2535 and RFC 4034. It can also generate keys for use with TSIG (Transaction Signatures), as defined in RFC 2845.
      The name of the key is specified on the command
      line.  For DNSSEC keys, this must match the name of the zone for
      which the key is being generated.
    
algorithm
            Selects the cryptographic algorithm.  For DNSSEC keys, the value
            of algorithm must be one of RSAMD5, RSASHA1,
            DSA, NSEC3RSASHA1, NSEC3DSA, RSASHA256 or RSASHA512.
            For TSIG/TKEY, the value must
            be DH (Diffie Hellman), HMAC-MD5, HMAC-SHA1, HMAC-SHA224,
            HMAC-SHA256, HMAC-SHA384, or HMAC-SHA512.  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.
keysizeSpecifies 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 keys must be between 1 and 512 bits.
nametype
            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.  Defaults to ZONE for DNSKEY
	    generation.
          
classIndicates 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.
flagSet the specified flag in the flag field of the KEY/DNSKEY record. The only recognized flag is KSK (Key Signing Key) DNSKEY.
generatorIf 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.
protocolSets 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.
randomdev
            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.
          
strengthSpecifies the strength value of the key. The strength is a number between 0 and 15, and currently has no defined purpose in DNSSEC.
type
            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.
          
levelSets 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.
    
nnnn is the key name.
        
aaa is the numeric representation
          of the
          algorithm.
        
iiiii is the key identifier (or
          footprint).
        
dnssec-keygen 
      creates two files, 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 algorithms 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.