OPENSSL-DHPARAM(1SSL)

📦
version 4.0.3 · 13 versions
, in ubuntu stonking

💖 OPENSSL-DHPARAM 💖

okay bestie, welcome to the openssl-dhparam page — that's the one in the OpenSSL manual, section 1SSL, and she's here to help you with DH parameter manipulation and generation. no cap. let's get into it 🦋

✨ NAME ✨

openssl-dhparam — DH parameter manipulation and generation. that's it, that's the whole vibe. 💅

🌸 SYNOPSIS 🌸

openssl dhparam [-help] [-inform DER|PEM] [-outform DER|PEM] [-in
filename] [-out filename] [-dsaparam] [-check] [-noout] [-text]
[-verbose] [-quiet] [-2] [-3] [-5] [-rand files] [-writerand file]
[-provider name] [-provider-path path] [-provparam [name:]key=value]
[-propquery propq] [numbits]

literally the whole thing up there, keep it in your notes 📝

🎀 DESCRIPTION 🎀

so this command is the one you use to manipulate DH parameter files. that's her job, she's employed. 💼

and listen — if you wanna see how to generate a key using a named safe prime group without generating intermediate parameters, go look at "EXAMPLES" in openssl-genpkey(1). no need to do all that extra work when you don't have to, fr fr. 🫶

✨ OPTIONS ✨

the way that there are SO many flags... let's go one by one, we're not skipping a single one 🧚

  • -help — prints out a usage message. the classic. the icon. when in doubt, ask for help. 💜
  • -inform DER|PEM, -outform DER|PEM — these set the input format and the output format, and the default is PEM. the object plays nice with the PKCS#3 DHparameter structure. if you want details, go see openssl-format-options(1). 📎
  • -in filename — tells her which input file to read parameters from. if you don't give this option, she reads from standard input. 🌈
  • -out filename — tells her which output file to write parameters to. if this option isn't there, standard output gets used. heads up bestie: the output filename can be the same as the input filename, and that means the file contents get replaced. and note that file I/O is not atomic — the output file is truncated and then written. so like, don't come for me if something goes sideways. 😭
  • -dsaparam — if you use this, then DSA rather than DH parameters are read or created, and they get converted to DH format. otherwise, safe primes (the kind where (p-1)/2 is also prime) will be used for DH parameter generation.

DH parameter generation with the -dsaparam option is much faster. but beware — with those DSA-style DH parameters, you should create a fresh DH key for each use to avoid small-subgroup attacks that might be possible otherwise. yes ma'am, security first. 🔥

  • -check — performs numerous checks to see if the parameters you supplied are valid, and displays a warning if they're not. she's checking you, gently. 👑
  • -2, -3, -5 — the generator to use, either 2, 3 or 5. if one of these is present then the input file is ignored and parameters are generated instead. if none of them are present but numbits is present, then parameters are generated with the default generator 2. 🍓
  • numbits — this says a parameter set should be generated of size numbits. it must be the last option. if it's present then the input file is ignored and parameters are generated instead. if it's not present but a generator (-2, -3 or -5) is present, parameters are generated with a default length of 2048 bits. the minimum length is 512 bits, and the maximum length is 10000 bits. know your limits babe 💅
  • -noout — inhibits the output of the encoded version of the parameters. so she just... doesn't. 🙈
  • -text — prints out the DH parameters in human readable form. for when you wanna actually read the thing. 📖
  • -rand files, -writerand file — see "Random State Options" in openssl(1) for the details, bestie. ✨
  • -provider name
  • -provider-path path
  • -provparam [name:]key=value
  • -propquery propq — all of these live under the provider umbrella. see "Provider Options" in openssl(1), plus provider(7) and property(7). 🧚
  • -verbose — enables the output of progress messages, which is super handy when you're running commands interactively that might take a long time to execute. she'll keep you company while you wait. 🫶
  • -quiet — suppresses the output of progress messages, which might be undesirable in batch scripts or pipelines. sometimes silence is the moment. 🤫

🌸 NOTES 🌸

this command replaces the dh and gendh commands of previous releases. out with the old, in with the new. slay. 💖

🦋 SEE ALSO 🦋

go read your siblings, iykyk 📚

💜 HISTORY 💜

  • the -C option was removed in OpenSSL 3.0.
  • the -engine option was removed in OpenSSL 4.0.

gone but not forgotten 🕊️

Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

and that's the whole page, bestie!! 🎀 this was OpenSSL 4.0.3, dated 2026-09-29, and it's OPENSSL-DHPARAM(1SSL) — go forth and generate those parameters, you're the main character now. periodt. 💅✨🦋

📦 where this page comes from