openssl-dhparam

Print out a usage message.

The input format and output format; the default is PEM. The object is compatible with the PKCS#3 DHparameter structure. See openssl-format-options(1) for details.

This specifies the input file to read parameters from or standard input if this option is not specified.

This specifies the output file to write parameters to. Standard output is used if this option is not present. The output filename can be the same as the input filename, which leads to replacing the file contents. Note that file I/O is not atomic. The output file is truncated and then written.

If this option is used, DSA rather than DH parameters are read or created; they are converted to DH format. Otherwise, safe primes (such that (p-1)/2 is also prime) will be used for DH parameter generation. DH parameter generation with the -dsaparam option is much faster. Beware that with such DSA-style DH parameters, a fresh DH key should be created for each use to avoid small-subgroup attacks that may be possible otherwise.

Performs numerous checks to see if the supplied parameters are valid and displays a warning if not.

The generator to use, either 2, 3 or 5. If present then the input file is ignored and parameters are generated instead. If not present but numbits is present, parameters are generated with the default generator 2.

This option inhibits the output of the encoded version of the parameters.

This option prints out the DH parameters in human readable form.

See "Engine Options" in openssl(1). This option is deprecated.

See "Random State Options" in openssl(1) for details.

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See "Provider Options" in openssl(1), provider(7), and property(7).

This option enables the output of progress messages, which is handy when running commands interactively that may take a long time to execute.

This option suppresses the output of progress messages, which may be undesirable in batch scripts or pipelines.