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 SSL, TLS

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.. contents::

   :local:

Generate a self-signed certificate

==================================

``openssl`` allows to generate self-signed certificate by a single command (``-newkey``

instructs to generate a private key and ``-x509`` instructs to issue a self-signed

certificate instead of a signing request)::

  openssl req -x509 -newkey rsa:4096 \

    -keyout my.key -passout pass:123456 -out my.crt \

    -days 365 \

    -subj /CN=localhost/O=home/C=US/emailAddress=me@mail.internal \

    -addext "subjectAltName = DNS:localhost,DNS:web.internal,email:me@mail.internal" \

    -addext keyUsage=digitalSignature -addext extendedKeyUsage=serverAuth

You can generate a private key and construct a self-signing certificate in separate steps::

  openssl genrsa -out my.key -passout pass:123456 2048

  openssl req -x509 \

    -key my.key -passin pass:123456 -out my.csr \

    -days 3650 \

    -subj /CN=localhost/O=home/C=US/emailAddress=me@mail.internal \

    -addext "subjectAltName = DNS:localhost,DNS:web.internal,email:me@mail.internal" \

    -addext keyUsage=digitalSignature -addext extendedKeyUsage=serverAuth

Review the resulting certificate::

  openssl x509 -text -noout -in my.crt

.. note::

   With ``openssl`` we can add an extra step:

   * generate private key (``openssl genrsa``)

   * generate CSR (``openssl req -new``)

   * sign CSR with private key (``openssl x509``)

   The problem here is that ``openssl x509`` doesn't support ``-addext`` like option so we

   need to craft a config file... Of cause with Bash syntax ``<(...)`` we can add required

   extensions::

     openssl genrsa -out my.key -passout pass:123456 2048

     openssl req -new \

       -key my.key -passin pass:123456 -out my.csr \

       -subj /CN=localhost/O=home/C=US/emailAddress=me@mail.internal

     openssl x509 -req \

       -in my.csr -signkey my.key -passin pass:123456 -out my.crt \

       -days 3650 -CAcreateserial \

       -extensions v3_ca \

       -extfile <( \

         echo "[v3_ca]"; \

         echo "extendedKeyUsage=serverAuth"; \

         echo "subjectAltName=DNS:localhost,DNS:web.internal,email:me@mail.internal")

Java ``keytool`` creates PKCS#12 store::

  keytool -genkeypair -keystore my.p12 -alias master \

    -storetype pkcs12 -keyalg RSA -keysize 2048 -validity 3650 \

    -storepass 123456 \

    -dname "CN=localhost,O=home,C=US" \

    -ext 'san=dns:localhost,dns:web.internal,email:me@mail.internal'

To export the self-signed certificate::

  keytool -exportcert -keystore my.p12 -file my.crt \

    -alias master -rfc -storepass 123456

Review the resulting certificate::

  keytool -printcert -file my.crt

https://stackoverflow.com/questions/10175812/how-to-create-a-self-signed-certificate-with-openssl/64733092#64733092

  How to create a self-signed certificate with OpenSSL.

Verify self-signed certificate

==============================

Use a private key and corresponding self-signed certificate to launch a server::

  openssl s_server -accept 8000 -www -key my.key -cert my.crt

Clients should use self-signed certificate for verification::

  echo | openssl s_client -servername localhost -connect localhost:8000 -CAfile my.crt

  curl -v --cacert my.crt https://localhost:8000

There is no certificate chain so the check is trivial for self-signed certificates...