How to generate openssl certificate with expiry less than one day?

user_707519 0
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I am trying to create CA signed End Entity certificate using openssl commands as shown below, in Linux:

# openssl genrsa -des3 -out clientkey.pem 2048
# openssl req -new -key clientkey.pem -out clientcert.csr
# cp clientkey.pem clientkey.pem.org
# openssl rsa -in clientkey.pem.org -out clientkey.pem
# openssl x509 -req -days 1 -in clientcert.csr -out clientcert.pem -CA cacert.pem -CAkey cakey.pem -CAcreateserial

Is it possible to specify the expiry time in hours, instead of days? I need to generate certificates with, say 1 hour expiry time, for some testing.

Openssl command seems to support some options to specify startdate and enddate, but I am not able to figure out how to use that. ( I am assuming enddate might support specifying date, and time).

#openssl x509 -req -startdate 120814050000Z -enddate 120814060000Z -in clientcert.csr -out clientcert.pem -CA cacert.pem -CAkey cakey.pem -CAcreateserial

unknown option 120814050000Z
usage: x509 args
.
.
-startdate      - notBefore field
-enddate        - notAfter field
.
.
-days arg       - How long till expiry of a signed certificate - def 30 days
openssl linux
5 Answers

Step-1. Install faketime

sudo apt-get install faketime

Step-2. Generate expired certificate a day before currentdate.

faketime 'last friday 5 pm' /bin/bash -c 'openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 6 -nodes'

Step-3 Verify the certificate validity date

openssl x509 -noout -text -in cert.pem

Certificate Validity dates - Screenshot

user_18407740

You can set the -days option to 0:

openssl x509 -req -days 0 -in clientcert.csr -signkey cert.key -out ssl.crt

That will create a certificate with a notBefore and notAfter equal to the current time (i.e. you certificate will expire immediately).

user_8295710
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