GENRSA(1)                           OpenSSL                          GENRSA(1)



NAME
       genrsa - generate an RSA private key

LIBRARY
       libcrypto, -lcrypto

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 its unique id string) will cause genrsa 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
       openssl_gendsa(1)



1.0.1h                            2009-07-19                         GENRSA(1)

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