Cloning a CSR or Cert. for a new CSR with a new key?

Douglas Morris dougbmorris at
Fri Jan 31 00:25:38 UTC 2020

Thanks, Dw.
Interesting. I think I misunderstood this explanation about the -signkey <file> option: "This option causes the input file to be self signed using the supplied private key."
Your input has me thinking that a certificate signing request is in fact self-signed like a self-signed certificate is self-signed. I think I mistakenly supposed any self-signing meant acting like a "mini CA". I shall give those two x509 options, '-x509toreq' and '-signkey', a try.

Douglas Morris

    On Thursday, January 30, 2020, 3:51:45 PM EST, Dirk-Willem van Gulik <dirkx at> wrote:  

On 30 Jan 2020, at 21:38, Douglas Morris via openssl-users <openssl-users at> wrote:
I am trying to implement automated domain certificate renewal. A certificate signing request is sent to an ACME server and on success a certificate is returned. I'd like to be able to call OpenSSL to make a new key and then make a new certificate signing request just like the old one except for the replacement key pair file.
I suppose the complete information beyond the new key data is available both in the old crs and the old certificate. I'm looking at the manpages of OpenSSL subcommands 'req' and 'x509'. The openssl x509 option '-x509toreq' gave me a momentary rush of hope, but then I read about the '-signkey' option, which seems to be exclusively about self-signing.

Is 'cloning' the csr or cert. information semantically logical? Is it possible with OpenSSL?

If I can't reliably extract the relevant data from the old csr or old certification, I suppose I must do it as usual with a dedicated config file and the '-batch' option:     openssl req -key <key> -new -config <config.ini> -outform PEM -out <outfile> -batch

openssl x509 -x509toreq should do the trick
  # generate test cert openssl req -x509 -new -subj /CN=foo -nodes -keyout x.key > x.crt openssl x509 -in x.crt -noout -text
 # turn test cert in a request openssl x509 -x509toreq -signkey x.key < x.crt
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