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GENRSA(1)                                          OpenSSL                                         GENRSA(1)



NAME
       genrsa - generate an RSA private key

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

       -engine id
           specifying an engine (by it's unique id string) will cause req to attempt to obtain a functional
           reference to the specified engine, thus initialising it if needed. The engine will then be set as
           the default for all available algorithms.

       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).

       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)



0.9.8                                            2003-01-30                                        GENRSA(1)