OpenSSL Certificate (Version 3) with Subject Alternative Name

Question

I\'m using the OpenSSL command line tool to generate a self signed certificate. It seems to be working correctly except for two issues. I can\'t get it to create a .cer with a S

Answer 1

I referred to several pages, and the most significant helps are from 1. https://geekflare.com/san-ssl-certificate/, 2. https://certificatetools.com/ (see answer from user40662), and 3. answer from Raghu K Nair about the command usage.

Then my successful try:

san.cnf

[ req ]
default_bits       = 2048
default_md         = sha256
distinguished_name = req_distinguished_name
req_extensions     = v3_req
[ req_distinguished_name ]
countryName            = CN                     # C=
stateOrProvinceName    = Shanghai               # ST=
localityName           = Shanghai               # L=
#postalCode             = 200000                 # L/postalcode=
#streetAddress          = "My Address"           # L/street=
organizationName       = My Corporation         # O=
organizationalUnitName = My Department          # OU=
commonName             = myname.mysoftware.mycorporation.com # CN=
emailAddress           = myname@example.com     # CN/emailAddress=
[ v3_req ]
subjectAltName = @alt_names
[ alt_names ]
DNS.1   = myname.mysoftware.mycorporation.com
#DNS.2   = other2.com
#DNS.3   = other3.com

Command:

openssl req -x509 -nodes -days 365 -subj "/C=CN/ST=Shanghai/L=Shanghai/O=My Corporation/OU=My Department/CN=myname.mysoftware.mycorporation.com/emailAddress=myname@example.com" -keyout privateKey.pem -out certificate.crt -config san.cnf -extensions v3_req