Demos of create self-signed CA cert, create client cert with self-signed CAcert and verify client cert using openssl APIs.

$ openssl req -nodes -newkey rsa:1024 -sha1 -keyout rootkey.pem -out rootreq.pem

$ openssl x509 -req -in rootreq.pem -sha1 -signkey rootkey.pem -out rootcert.pem

$ sudo mkdir /usr/share/ca-certificates/extra
$ sudo cp rootcert.pem /usr/share/ca-certificates/extra/rootcert.crt
$ sudo dpkg-reconfigure ca-certificates
$ sudo update-ca-certificates

$ openssl req -nodes -newkey rsa:1024 -sha1 -keyout userkey.pem -out userreq.pem

$ openssl x509 -req -in userreq.pem -sha1 -CA /etc/ssl/certs/rootcert.pem -CAkey rootkey.pem -CAcreateserial -out usercert.pem

$ openssl verify -CAfile rootcert.pem usercert.pem

Before we can generate a CRL, we must create a crlnumber file, but we look the openssl.cnf at first.

• modify openssl.cnf (ubuntu: /etc/ssl/openss.cnf, centos: /etc/pki/tls/openssl.cnf), find the section CA_default and modify it as follow:

[ CA_default ]

dir = /etc/ssl/demoCA # Where everything is kept
certs = $dir/certs # Where the issued certs are kept
crl_dir = $dir/crl # Where the issued crl are kept
database = $dir/index.txt # database index file.
# unique_subject = no # Set to 'no' to allow creation of
# several ctificates with same subject.
new_certs_dir = $dir/newcerts # default place for new certs.

certificate = $dir/rootcert.pem # The CA certificate
serial = $dir/serial # The current serial number
crlnumber = $dir/crlnumber # the current crl number
# must be commented out to leave a V1 CRL
crl = $dir/crl.pem # The current CRL
private_key = $dir/private/rootkey.pem # The private key

• copy the rootkey.pem and rootcert.pem to the related dir

• create index.txt file:
  $ > /etc/ssl/demoCA/index.txt

• create crlnumber file:
  $ echo 1024 > /etc/ssl/demoCA/crlnumber

$ openssl ca -gencrl -out /etc/ssl/demoCA/crl/crl.pem

$ openssl crl -in /etc/ssl/demoCA/crl/crl.pem -text

Certificate Revocation List (CRL):
Version 2 (0x1) Signature Algorithm: sha256WithRSAEncryption
Issuer: /C=UK/CN=OpenSSL Group/C=UK/CN=Openssl
Last Update: Mar 30 03:56:23 2015 GMT
Next Update: Apr 29 03:56:23 2015 GMT
CRL extensions:
X509v3 CRL Number:
4133
No Revoked Certificates.
Signature Algorithm: sha256WithRSAEncryption
...

$ openssl ca -revoke usercert.pem

$ openssl ca -gencrl -out /etc/ssl/demoCA/crl/crl.pem

$ openssl crl -in /etc/ssl/demoCA/crl/crl.pem -text

Certificate Revocation List (CRL):
Version 2 (0x1)
Signature Algorithm: sha256WithRSAEncryption
Issuer: /C=UK/CN=OpenSSL Group/C=UK/CN=Openssl
Last Update: Mar 30 03:59:11 2015 GMT
Next Update: Apr 29 03:59:11 2015 GMT
CRL extensions:
X509v3 CRL Number:
4134
Revoked Certificates:
Serial Number: 0400
Revocation Date: Mar 30 03:57:52 2015 GMT
Signature Algorithm: sha256WithRSAEncryption
...

See mkcacert.c

See mkclientcert.c

See verify.c

See revoke.c

See mkcrl.c