create tsa (timestamping) certificate with openssl - add a extendedKeyUsage in a certificate

Question

I'd like to create a tsa certificate for my timestamping service.

First I create a root certificate

openssl genrsa -out tsaroot.key 4096 -config openssl.cnf
openssl req -new -x509 -days 1826 -key tsaroot.key -out tsaroot.crt -config openssl.cnf

Then I create the tsa certificate

openssl genrsa -des3 -out tsa.key 4096 -config openssl.cnf
openssl req -new -key tsa.key -out tsa.csr -config openssl.cnf
openssl x509 -req -days 730 -in tsa.csr -CA tsaroot.crt -CAkey tsaroot.key -set_serial 01 -out tsa.crt
openssl pkcs12 -export -out tsa.p12 -inkey tsa.key -in tsa.crt -chain -CAfile tsaroot.crt

In my openssl.cnf file, i add the following line :

extendedKeyUsage = critical,timeStamping

Howerver, the created certificate doesn't seem to include the extendeKeyUsage (when i try to read it with bouncy castle i got a "Certificate must have an ExtendedKeyUsage extension." exception

How can I generate a valid tsa certificate (with the correct extendedKeyUsage value included)?

Thanks

Answer 1

Try with the following:

1. Add a named section in the openssl.cnf file:

   [v3_tsa]
   extendedKeyUsage = critical,timeStamping
   

2. When generating the TSA certificate from the tsr, add the switch -extensions:

   openssl x509 -req ... -extensions v3_tsa