genrsa(1)

     GENRSA(1)              0.9.6h (2000-04-12)              GENRSA(1)

     NAME
          genrsa - generate an RSA private key

     SYNOPSIS
          openssl genrsa [-out filename] [-passout arg] [-des] [-des3]
          [-idea] [-f4] [-3] [-rand file(s)] [numbits]

     DESCRIPTION
          The genrsa command generates an RSA private key.

     OPTIONS
          -out filename
              the output filename. If this argument is not specified
              then standard output is used.

          -passout arg
              the output file password source. For more information
              about the format of arg see the PASS PHRASE ARGUMENTS
              section in openssl(1).

          -des|-des3|-idea
              These options encrypt the private key with the DES,
              triple DES, or the IDEA ciphers respectively before
              outputting it. If none of these options is specified no
              encryption is used. If encryption is used a pass phrase
              is prompted for if it is not supplied via the -passout
              argument.

          -F4|-3
              the public exponent to use, either 65537 or 3. The
              default is 65537.

          -rand file(s)
              a file or files containing random data used to seed the
              random number generator, or an EGD socket (see
              RAND_egd(3)).  Multiple files can be specified separated
              by a OS-dependent character.  The separator is ; for
              MS-Windows, , for OpenVMS, and : for all others.

          numbits
              the size of the private key to generate in bits. This
              must be the last option specified. The default is 512.

     NOTES
          RSA private key generation essentially involves the
          generation of two prime numbers. When generating a private
          key various symbols will be output to indicate the progress
          of the generation. A . represents each number which has
          passed an initial sieve test, + means a number has passed a
          single round of the Miller-Rabin primality test. A newline
          means that the number has passed all the prime tests (the
          actual number depends on the key size).

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     GENRSA(1)              0.9.6h (2000-04-12)              GENRSA(1)

          Because key generation is a random process the time taken to
          generate a key may vary somewhat.

     BUGS
          A quirk of the prime generation algorithm is that it cannot
          generate small primes. Therefore the number of bits should
          not be less that 64. For typical private keys this will not
          matter because for security reasons they will be much larger
          (typically 1024 bits).

     SEE ALSO
          gendsa(1)

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