tests/sslcerts/README

transaction: clarify the logic around pre-finalize/post-finalize

I am taking a bit more verbose route, but I find it easier to follow for people
who (re)discover the code.

(This is a gratuitous cleanup I did while looking at something else.)

Differential Revision: https://phab.mercurial-scm.org/D8176

Generate a private key (priv.pem):

  $ openssl genrsa -out priv.pem 2048

Generate 2 self-signed certificates from this key (pub.pem, pub-other.pem):

  $ openssl req -new -x509 -key priv.pem -nodes -sha256 -days 9000 \
    -out pub.pem -batch -subj '/CN=localhost/emailAddress=hg@localhost/'
  $ openssl req -new -x509 -key priv.pem -nodes -sha256 -days 9000 \
    -out pub-other.pem -batch -subj '/CN=localhost/emailAddress=hg@localhost/'

Now generate an expired certificate by turning back the system time:

  $ faketime 2016-01-01T00:00:00Z \
    openssl req -new -x509 -key priv.pem -nodes -sha256 -days 1 \
    -out pub-expired.pem -batch -subj '/CN=localhost/emailAddress=hg@localhost/'

Generate a certificate not yet active by advancing the system time:

  $ faketime 2030-01-1T00:00:00Z \
    openssl req -new -x509 -key priv.pem -nodes -sha256 -days 1 \
    -out pub-not-yet.pem -batch -subj '/CN=localhost/emailAddress=hg@localhost/'

Generate a passphrase protected client certificate private key:

  $ openssl genrsa -aes256 -passout pass:1234 -out client-key.pem 2048

Create a copy of the private key without a passphrase:

  $ openssl rsa -in client-key.pem -passin pass:1234 -out client-key-decrypted.pem

Create a CSR and sign the key using the server keypair:

  $ printf '.\n.\n.\n.\n.\n.\nhg-client@localhost\n.\n.\n' | \
    openssl req -new -key client-key.pem -passin pass:1234 -out client-csr.pem
  $ openssl x509 -req -days 9000 -in client-csr.pem -CA pub.pem -CAkey priv.pem \
    -set_serial 01 -out client-cert.pem

When replacing the certificates, references to certificate fingerprints will
need to be updated in test files.

Fingerprints for certs can be obtained by running:

  $ openssl x509 -in pub.pem -noout -sha1 -fingerprint
  $ openssl x509 -in pub.pem -noout -sha256 -fingerprint