101

I am using following code to generate keys:

apt-get -qq -y install openssl;
mkdir -p /etc/apache2/ssl;
openssl genrsa -des3 -out server.key 1024;
openssl req -new -key server.key -out server.csr;
cp server.key server.key.org;
openssl rsa -in server.key.org -out server.key;
openssl x509 -req -days 12000 -in server.csr -signkey server.key -out server.crt;
mv server.crt  /etc/apache2/ssl/cert.pem;
mv server.key  /etc/apache2/ssl/cert.key;
rm -f server.key.orig;
rm -f server.csr

I have two questions:

  1. How can I skip the passphrase prompting? Would it be reasonably safe for me to do so? (as in it should not be downright foolish like anyone should be able to hack the certificate)

  2. How do I avoid the prompting for the country name, organization etc. I hope I can give them on command prompt (the man page shows only top level options for OpenSSL)

5 Answers 5

171

Edit: This is by far my most popular answer, and it's been a few years on now so I've added an ECDSA variant. If you can use ECDSA you should.


You can supply all of that information on the command line.

One step self-signed password-less certificate generation:

RSA Version

openssl req \
    -new \
    -newkey rsa:4096 \
    -days 365 \
    -nodes \
    -x509 \
    -subj "/C=US/ST=Denial/L=Springfield/O=Dis/CN=www.example.com" \
    -keyout www.example.com.key \
    -out www.example.com.cert

ECDSA version

openssl req \
    -new \
    -newkey ec \
    -pkeyopt ec_paramgen_curve:prime256v1 \
    -days 365 \
    -nodes \
    -x509 \
    -subj "/C=US/ST=Denial/L=Springfield/O=Dis/CN=www.example.com" \
    -keyout www.example.com.key \
    -out www.example.com.cert

All of the openssl subcommands have their own man page. See man req.


Specifically addressing your questions and to be more explicit about exactly which options are in effect:

  1. The -nodes flag signals to not encrypt the key, thus you do not need a password. You could also use the -passout arg flag. See PASS PHRASE ARGUMENTS in the openssl(1) man page for how to format the arg.

  2. Using the -subj flag you can specify the subject (example is above).

13
  • 3
    Reading stuff via "-subj" works great, however - for me - only when OPENSSL_CONF is NOT set. IOW: if OPENSSL_CONF is set, OpenSSL will try reading from there, and ignore "-subj" command line argument. Took me a while to figure out.
    – oberstet
    Mar 27, 2012 at 21:17
  • oberstet: Yes, that is true.
    – bahamat
    Mar 30, 2012 at 21:48
  • Is it possible to pass the subject key itself from stdin? I have tried "-key stdin", "-key fd:1" and "-key -" .. with no luck.
    – oberstet
    Apr 3, 2012 at 1:39
  • 1
    @JeremyBaker: No, you'll need a two step process for that. Omit the -x509 and -days to generate a CSR instead of a certificate then use your usual CA signing method.
    – bahamat
    Jun 9, 2015 at 18:07
  • 2
    @jww - and that time has come. Starting with Chrome v58, when attempting to load a secure page but the certificate doesn't contain a matching subjectAltName, it shows a privacy error page with the error message "NET::ERR_CERT_COMMON_NAME_INVALID". Clicking on the advanced button shows the message "... its security certificate is from [missing_subjectAltName]" May 4, 2017 at 10:52
12

Doesn't -passin option do the trick for you?

With file:pathname form you can be quite safe with permissions 600 for that file.

2
  • Saw the option in man page. Looks like I can have the passphrase that way without prompting. Thanks!
    – JP19
    Dec 28, 2010 at 6:01
  • And with -passin 'pass:YOUR_PASSWORD'? - doc: openssl.org/docs/man1.0.2/apps/…
    – andras.tim
    Nov 6, 2018 at 11:29
7

The accepted answer needs a couple of small corrections. EC Lines:

-newkey ec
-pkeyopt ec_paramgen_curve:prime256v1

should be:

 -newkey ec \
 -pkeyopt ec_paramgen_curve:prime256v1 \

On MacOS - OpenSSL 1.0.2f installed via brew I verified the the accepted answer as described below

  • To list available Elliptic curves:

    $ openssl ecparam -list_curves
    
  • To generate a key file:

    $ openssl ecparam -name secp256k1 -out secp256k1.pem
    
  • To generate the cert without password prompt:

    openssl req \
        -new \
        -newkey ec:secp256k1.pem \
        -days 365 \
        -nodes \
        -x509 \
        -subj "/C=US/ST=FL/L=Ocala/O=Home/CN=example.com" \
        -keyout server.key \
        -out server.crt
    
  • To view the cert:

    $ openssl x509 -noout -text -in server.crt
    
3
  • How is this different from the accepted answer?
    – Ramhound
    Jun 8, 2016 at 22:53
  • 1
    The only important difference is that I explicitly list the step of generating the pem file. The accepted answer is missing the two \ characters and it made me think that the command is incorrect. Jun 9, 2016 at 15:32
  • 1
    You might want to mention that fact. If the accepted answer is indeed incomplete, and is missing characters, important to highlight the differences and how your answer contains important significant information.
    – Ramhound
    Jun 9, 2016 at 17:20
4

Try the following command:

openssl genrsa -des3 -out user.key -passout pass:foo 1024

The skipping part is: -passout pass:foo.

1
2

@bahamat has a great answer. Unfortunately some versions of openssl throw an error when trying to create an ECDSA certificate with one command. The error goes something like:

routines:EVP_PKEY_CTX_ctrl:invalid operation:pmeth_lib.c:404

I was using openssl 1.0.1e-fips on CentOS 7.

Creating your certificate with the following 3 commands seems to work:

openssl ecparam -genkey -name prime256v1 -out key.pem
openssl req -new -key key.pem -out csr.pem -subj "/C=US/ST=Denial/L=Springfield/O=Dis/CN=www.example.com"
openssl req -x509 -days 365 -key key.pem -in csr.pem -out certificate.pem
1
  • Shouldn’t the last line end with server.crt? Dec 8, 2016 at 20:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy