How-to: Generate Internal CA

generate-internal-ca.md

Create your CA database to keep track of signed certificates

$ mkdir private certs cnf csr crl
$ touch index.txt
$ echo 1000 > serial

Create Your OpenSSL Config File

$ cat > cnf/ca.cnf <<EOF
# OpenSSL Root CA configuration file
# Copy to /root/ca/openssl_root.cnf

[ ca ]
default_ca = CA_default

[ CA_default ]
# Directory and file locations.
dir               = ./
certs             = $dir/certs
crl_dir           = $dir/crl
new_certs_dir     = $dir/certs
database          = $dir/index.txt
serial            = $dir/serial
RANDFILE          = $dir/private/.rand

# The root key and root certificate.
private_key       = $dir/private/ca.key.pem
certificate       = $dir/certs/ca.crt.pem

# For certificate revocation lists.
crlnumber         = $dir/crlnumber
crl               = $dir/crl/intermediate.crl.pem
crl_extensions    = crl_ext
default_crl_days  = 360

# SHA-1 is deprecated, so use SHA-2 or SHA-3 instead.
default_md        = sha384

name_opt          = ca_default
cert_opt          = ca_default
default_days      = 3650
preserve          = no
policy            = policy_strict

[ policy_strict ]
# The root CA should only sign intermediate certificates that match.
# See the POLICY FORMAT section of 'man ca'.
countryName             = match
stateOrProvinceName     = match
organizationName        = match
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional

[ policy_loose ]
# Allow the intermediate CA to sign a more diverse range of certificates.
# See the POLICY FORMAT section of the 'ca' man page.
countryName             = optional
stateOrProvinceName     = optional
localityName            = optional
organizationName        = optional
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional

[ req ]
# Options for the 'req' tool ('man req').
default_bits        = 2048
distinguished_name  = req_distinguished_name
string_mask         = utf8only

# SHA-1 is deprecated, so use SHA-2 or SHA-3 instead.
default_md          = sha256

# Extension to add when the -x509 option is used.
x509_extensions     = v3_ca

[ req_distinguished_name ]
countryName                     = Country Name (2 letter code)
stateOrProvinceName             = State or Province Name
localityName                    = Locality Name
0.organizationName              = Organization Name
organizationalUnitName          = Organizational Unit Name
commonName                      = Common Name
emailAddress                    = Email Address

# Optionally, specify some defaults.
countryName_default             = SG
stateOrProvinceName_default     = Singapore
localityName_default            = Singapore
0.organizationName_default      = Pivotal Inc.
organizationalUnitName_default  = Pivotal Root CA
emailAddress_default            = [email protected]

[ v3_ca ]
# Extensions for a typical CA ('man x509v3_config').
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical, CA:true
keyUsage = critical, digitalSignature, cRLSign, keyCertSign

[ v3_intermediate_ca ]
# Extensions for a typical intermediate CA ('man x509v3_config').
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical, CA:true, pathlen:0
keyUsage = critical, digitalSignature, cRLSign, keyCertSign
crlDistributionPoints = @crl_info
authorityInfoAccess = @ocsp_info

[ usr_cert ]
# Extensions for client certificates ('man x509v3_config').
basicConstraints = CA:FALSE
nsCertType = client, email
nsComment = "OpenSSL Generated Client Certificate"
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
keyUsage = critical, nonRepudiation, digitalSignature, keyEncipherment
extendedKeyUsage = clientAuth, emailProtection

[ server_cert ]
# Extensions for server certificates ('man x509v3_config').
basicConstraints = CA:FALSE
nsCertType = server
nsComment = "Pivotal Generated Server Certificate"
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer:always
keyUsage = critical, digitalSignature, keyEncipherment
extendedKeyUsage = serverAuth
#crlDistributionPoints = @crl_info
#authorityInfoAccess = @ocsp_info
subjectAltName = @alt_names

[alt_names]
DNS.0 = *.pivotal.io

[ crl_ext ]
# Extension for CRLs ('man x509v3_config').
authorityKeyIdentifier=keyid:always

[ ocsp ]
# Extension for OCSP signing certificates ('man ocsp').
basicConstraints = CA:FALSE
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
keyUsage = critical, digitalSignature
extendedKeyUsage = critical, OCSPSigning

#[crl_info]
#URI.0 = http://crl.grilledcheese.us/whomovedmycheese.crl

#[ocsp_info]
#caIssuers;URI.0 = http://ocsp.grilledcheese.us/cheddarcheeseroot.crt
#OCSP;URI.0 = http://ocsp.grilledcheese.us/
EOF

Create the Root CA's Private Key

$ openssl ecparam -genkey -name secp384r1 | openssl ec -aes256 -out private/ca.key.pem
read EC key
writing EC key
Enter PEM pass phrase: Password1
Verifying - Enter PEM pass phrase: Password1

Create the Root CA's Certificate

$ openssl req -config cnf/ca.cnf -new -x509 -sha384 -extensions v3_ca -key private/ca.key.pem -out certs/ca.crt.pem
    Enter pass phrase for private/ca.key.pem:
    You are about to be asked to enter information that will be incorporated
    into your certificate request.
    What you are about to enter is what is called a Distinguished Name or a DN.
    There are quite a few fields but you can leave some blank
    For some fields there will be a default value,
    If you enter '.', the field will be left blank.
    -----
    Country Name (2 letter code) [SG]:
    State or Province Name [Singapore]:
    Locality Name [Singapore]:
    Organization Name [Pivotal Inc.]:
    Organizational Unit Name [Pivotal Root CA]:
    Common Name []:*.pivotal.io
    Email Address [[email protected]]:

$ openssl x509 -noout -text -in certs/ca.crt.pem