OpenSSL Certificate (Version 3) with Subject Alter

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 Subject Alternative Name (critical) and I haven't been able to figure out how to create a cert that is Version 3 (not sure if this is critical yet but would prefer learning how to set the version).

Has anyone done this successfully? The default config (.cfg) file has seemingly clear documentation (seen below):

" This stuff is for subjectAltName and issuerAltname. Import the email address. subjectAltName=email:copy "

However this does not work. My hunch is that the subject Alternative Name is not showing up b/c it is not present in the V1 specs, which is why I'm also pursuing setting he version.

Here is the config file I'm using:

[ req ]
default_bits        = 2048 
default_keyfile     = privkey.pem 
distinguished_name  = req_distinguished_name
emailAddress        = [e-mail]
req_extensions          = v3_req
x509_extensions         = v3_ca

[req_distinguished_name]
C = [Press Enter to Continue]
C_default = US 
C_min = 2 
C_max = 2 

O = [Press Enter to Continue]
O_default = default 

0.OU=[Press Enter to Continue]
0.OU_default = default 
1.OU=[Press Enter to Continue]
1.OU_default = PKI 
2.OU=[Press Enter to Continue] 
2.OU_default = ABCD
commonName = Public FQDN of server 
commonName_max = 64

[ v3_req ]
basicConstraints = CA:FALSE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment

[ v3_ca ]
subjectKeyIdentifier   = hash
authorityKeyIdentifier = keyid:always,issuer:always
subjectAltName         = email:[e-mail]
issuerAltName          = issuer:copy

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           = [e-mail]     # 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=[e-mail]" -keyout privateKey.pem -out certificate.crt -config san.cnf -extensions v3_req

Answer 2

Here is the simple steps for you

While generating the CSR you should use -config and -extensions and while generating certificate you should use -extfile and -extensions

Here is the example

openssl req -new -nodes -keyout test.key  -out test.csr -days 3650 -subj "/C=US/ST=SCA/L=SCA/O=Oracle/OU=Java/CN=test cert" -config /etc/pki/tls/openssl.cnf -extensions v3_req
openssl x509 -req -days 3650 -in test.csr -CA cacert.pem -CAkey rootCA.key -CAcreateserial -out test.pem -extfile /etc/pki/tls/openssl.cnf  -extensions v3_req

hope this helps

Answer 3

I know this thread is a little old but just in case it works for anyone on windows, check that the file is UTF-8 encoded, in my case I was getting an error indicating there was an error with the .cnf file, so I opened it on Notepad++ set the file encoding to UTF-8, saved, and ran the openssl command again and it made the trick.