Preparing SSL certificates for production

Steps to generate SSL certificates for client-to-node encryption or node-to-node encryption using a self-signed Certificate Authority (CA) in a production environment.

To use SSL encryption for client-to-node encryption or node-to-node encryption, SSL certificates must be generated using openssl and keytool. To validate the certificates, a self-signed Certificate Authority (CA) can be generated for production use with Apache Cassandra. The certificates generated using these instructions can be used for both internode and client-to-node encryption. For internode encryption, all nodes must have the truststore that provides the chain of trust for the CA. The certificates in the truststore can either be signed by the self-signed certificate authority used here or by a trusted and recognized public certificate authority.

Procedure

Create a root CA certificate and key

Create the root CA certificate and key using openssl req. This command uses a certificate configuration file gen_rootCa_cert.conf.

openssl req 
    -config gen_rootCa_cert.conf 
    -new -x509 -nodes 
    -subj /CN=rootCa/OU=TestCluster/O=YourCompany/C=US/ 
    -keyout rootCa.key 
    -out rootCa.crt
    -days 365

# gen_rootCa_cert.conf
[ req ]
distinguished_name        = req_distinguished_name
prompt		      = no
output_password	    = myPass
default_bits		= 2048

[ req_distinguished_name ]
C			    = US
O			    = YourCompany
OU			   = TestCluster
CN			    = rootCa


Option	Description
-config	Configuration file to use
-new	Generate new certificate
-x509	Outputs a self-signed certificate
-nodes	If a private key is created, it is not encrypted
-subj	Sets subject name when processing
-keyout	Specify the private key filename to write
-out	Specify the certificate filename to write
-days	Specify the number of days for which to certify the certificate

The resulting files are the rootCA certificate and the rootCa private key.

An example of the rootCa.crt file:

An example of the rootCa.key file:

Verify the rootCa certificate

Verify the rootCa certificate.

 openssl x509
    -in rootCa.crt
    -text 
    -noout


Option	Description
-in	Specify the certificate filename to verify
-text	Print out the certificate in text form including the public key, signature algorithms, issuer and subject names, serial number any extensions present and any trust settings
-noout	Prevents output of the encoded version of the request

This command prints output to the console that is similar to this example:

Certificate:
    Data:
        Version: 1 (0x0)
        Serial Number: 10851234054762703412 (0x969753e168c0aa34)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=US, O=YourCompany, OU=TestCluster, CN=rootCa
        Validity
            Not Before: Sep 10 03:59:38 2016 GMT
            Not After : Sep 10 03:59:38 2017 GMT
        Subject: C=US, O=YourCompany, OU=TestCluster, CN=rootCa
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:d9:85:78:4e:7c:79:a7:cd:0c:f3:98:af:ac:85:
                    18:d1:f1:9f:0b:62:29:12:2c:d4:25:c5:f2:92:50:
                    d6:c9:a0:cc:cd:af:e8:3f:54:7a:2c:5d:67:96:c3:
                    b3:48:2b:2b:5e:1a:e1:4a:04:f7:7f:59:09:62:8e:
                    2d:c8:05:8b:7d:fd:e1:7c:17:1c:27:f4:99:28:ee:
                    76:b1:dd:d2:9b:40:40:a5:52:32:a2:0b:46:22:79:
                    9c:96:91:e3:2a:9f:64:11:5b:07:67:e5:89:0e:6b:
                    f7:3d:8f:db:4c:d3:8e:56:db:5d:9a:09:4f:cd:ca:
                    17:84:3e:91:ef:95:2c:b9:84:81:2b:0b:a3:08:e6:
                    ab:e2:4f:3f:85:33:96:9f:1d:0b:25:4b:a4:07:83:
                    b2:77:ff:4f:bf:d1:69:e2:2e:67:e5:b3:8d:ee:69:
                    32:57:ab:63:b0:af:f4:0e:ad:7b:f4:a4:14:ad:5b:
                    65:8c:cc:b1:30:85:39:8e:91:06:4d:4a:75:c5:72:
                    0e:f8:62:72:8d:5b:f0:7b:f9:85:02:d9:e2:fd:e7:
                    77:a4:6d:7e:65:cd:74:be:d8:ae:a9:cb:03:d2:e7:
                    99:2f:59:14:89:35:c3:de:4f:96:0e:a1:74:13:ae:
                    19:3e:b6:5b:79:65:23:2a:4c:6d:90:4e:75:60:4c:
                    a7:43
                Exponent: 65537 (0x10001)
    Signature Algorithm: sha256WithRSAEncryption
         9a:88:7a:c6:4a:1a:ef:5c:ae:57:12:4e:3b:6e:30:0d:f4:8d:
         22:98:00:88:fd:6e:8f:bb:6f:83:36:b4:c8:fb:36:db:5a:3c:
         a7:67:bf:df:8c:1d:45:a5:9d:cc:b9:dc:dc:8b:bc:70:ba:68:
         9a:6b:aa:f5:bf:36:fd:64:0d:c5:da:85:20:9c:b2:27:00:d3:
         65:46:7a:56:2b:12:49:79:2d:0e:c5:b7:98:33:f2:d7:40:2c:
         f8:72:47:b9:0f:5a:75:3b:22:fe:c3:9e:ae:1f:39:16:39:93:
         05:86:d3:0e:35:fa:06:c2:2b:c3:2c:20:14:19:db:ea:eb:9d:
         db:f1:8a:97:34:ed:96:c8:b9:2c:52:d6:28:75:6b:cb:1a:a7:
         83:e8:da:e0:26:59:6d:0e:bf:19:3d:36:85:d3:f6:77:fd:7b:
         80:68:02:8b:58:48:83:92:89:bf:f3:28:56:13:74:74:b6:fa:
         72:e7:aa:7f:12:ce:38:b1:a4:aa:45:de:bf:63:62:38:dc:e9:
         8d:02:13:47:0a:05:d4:d5:28:e3:90:d1:1e:2d:b9:3c:02:7c:
         fa:c9:54:ce:f8:a2:e0:00:db:7b:73:fe:49:f1:08:e8:01:13:
         76:76:9d:0a:70:3e:58:e7:df:1c:8d:f9:3a:ac:71:78:f3:bd:
         56:a5:ae:f3

Generate public/private key pair and keystore for each node

Repeat this command for each node. The files can be generated on a single node and distributed out to the nodes after the entire process is completed.

keytool -genkeypair 
    -keyalg RSA 
    -alias 10.200.175.15 
    -keystore 10.200.175.15.jks 
    -storepass myKeyPass 
    -keypass myKeyPass 
    -validity 365 
    -keysize 2048 
    -dname "CN=10.200.175.15, OU=TestCluster, O=YourCompany, C=US"


Option	Description
-genkeypair	Command to generate a public/private key pair
-keyalg	Specify the key algorithm
-alias	Assign an unique alias by which keystore entry is accessed
-keystore	Specify the keystore filename
-storepass	Specify the keystore password
-keypass	Specify the private key password
-validity	Specify the number of days for the keystore certificate validity
-keysize	Specify the size of the generated key
-dname	Specify the X.500 Distinguished Name to be associated with the value of alias

In this example, the node IP address is 10.200.175.15 and the keystore filename incorporates that IP address with a suffix of jks (Java KeyStore). While the keystore can be named with any convention, the examples here use the IP address in order to map the files to the nodes. The dname sets the CN value to the node's IP address or FQDN as well. The storepass and keypass must be the same value.

Check certificates

The certificates can be checked once generated:

keytool -list 
    -keystore 10.200.175.15.jks 
    -storepass myKeyPass

An example keystore file:

Keystore type: JKS
Keystore provider: SUN

Your keystore contains 1 entry

10.200.175.15, Sep 10, 2016, PrivateKeyEntry, 
Certificate fingerprint (SHA1): D6:1B:6C:FE:E3:3B:4B:3D:E0:F0:38:EA:54:AD:F0:E7:1E:D4:CB:4D

Export certificate signing request (CSR) for each node

Once the node certificate and key are generated, a certificate signing request (CSR) is exported. The CSR will be signed with the rootCa certificate to verify that the node's certificate is trusted.

keytool -certreq
    -keystore 10.200.175.15.jks 
    -alias 10.200.175.15 
    -file 10.200.175.15.csr 
    -keypass myKeyPass 
    -storepass myKeyPass 
    -dname "CN=10.200.175.15, OU=TestCluster, O=YourCompany, C=US"


Option	Description
-certreq	Command to export a CSR
-file	Specify the CSR filename
-alias	Assign an unique alias by which keystore entry is accessed
-keystore	Specify the keystore filename
-storepass	Specify the keystore password
-keypass	Specify the private key password
-dname	Specify the X.500 Distinguished Name to be associated with the value of alias

An example CSR file:

-----BEGIN NEW CERTIFICATE REQUEST-----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-----END NEW CERTIFICATE REQUEST-----

Sign node certificate with rootCa for each node

The CSR is input, signed with the rootCa certificate and a signed node certificate is created.

openssl x509 
    -req 
    -CA rootCa.crt 
    -CAkey rootCa.key 
    -in 10.200.175.15.csr 
    -out 10.200.175.15.crt_signed 
    -days 365 
    -CAcreateserial 
    -passin pass:myPass


Option	Description
-req	Specify that the input file is a CSR
-CA	Identify the rootCa certificate
-CAkey	Identify the rootCa key
-in	Specify the input filename from which to read a certificate
-out	Specify the output filename for the signed certificate
-CAcreateserial	Specify that a CA serial number file is created if it does not exist
-days	Specify the number of days for which to certify the certificate
-passin	Specify the key password source

An example of the signed certificate:

Verify the signed certificate for each node

Check the signed certificate by designating the rootCa certificate and the signed certificate to verify:
```
openssl verify -CAfile rootCa.crt 10.200.175.15.crt_signed
```
If the verification succeeds, a console message is returned:
```
10.200.175.15.crt_signed: OK
```

Import rootCa certificate to each node keystore

Use keytool -importcert to import the rootCa certificate into each node keystore:

keytool -importcert 
    -keystore 10.200.175.15.jks 
    -alias rootCa  
    -file rootCa.crt 
    -noprompt  
    -keypass myKeyPass 
    -storepass myKeyPass

The -noprompt option allows the command to use the specified values rather than prompting for input.

The keystore file now has two entries, one for the rootCa certificate and one for the node certificate:

Keystore type: JKS
Keystore provider: SUN

Your keystore contains 2 entries

rootca, Sep 10, 2016, trustedCertEntry, 
Certificate fingerprint (SHA1): CD:F2:A5:6F:EC:DA:B9:9E:C1:8D:89:09:AE:FF:DB:BD:56:F6:7D:79
10.200.175.15, Sep 10, 2016, PrivateKeyEntry, 
Certificate fingerprint (SHA1): D6:1B:6C:FE:E3:3B:4B:3D:E0:F0:38:EA:54:AD:F0:E7:1E:D4:CB:4D

Import node's signed certificate into node keystore for each node

```
keytool -importcert
    -keystore 10.200.175.15.jks 
    -alias 10.200.175.15  
    -file 10.200.175.15.crt_signed 
    -noprompt 
    -keypass myKeyPass 
    -storepass myKeyPass 
```
The resulting file will appear similar to the result from the previous step, but the node certificate originally created is replaced with the signed node certificate.

Create a server truststore

A server truststore file can be used to establish a chain of trust between the nodes of the cluster.

keytool -importcert 
    -keystore generic-server-truststore.jks 
    -alias rootCa  
    -file rootCa.crt 
    -noprompt
    -keypass myPass 
    -storepass truststorePass

The resulting truststore file can be inspected using the

keytool
                            -list

command:

keytool -list 
    -keystore generic-server-truststore.jks 
    -storepass truststorePass

and an example of the truststore file will include a rootCa certificate entry:

Keystore type: JKS
Keystore provider: SUN

Your keystore contains 1 entry

rootca, Sep 10, 2016, trustedCertEntry, 
Certificate fingerprint (SHA1): CD:F2:A5:6F:EC:DA:B9:9E:C1:8D:89:09:AE:FF:DB:BD:56:F6:7D:79

Copy the truststore file to each node

The truststore file must be copied to each node. If a node is used to generate the file, copy the file to a location of choice and name the file with a standard format, such as server-truststore.jks. This example shows the copy command for a Linux server with a tarball installation of Cassandra and stores the file in the configuration directory of Cassandra:
```
cp ~/generic-server-truststore.jks /usr/local/lib/cassandra/conf/server-truststore.jks
```

Copy the each node keystore file to each node

Each node file must have a copy of its keystore file. If a node is used to generate the file, copy the file to a location of choice. This example shows the secure remote copy commands for a Linux server with a tarball installation of Cassandra, where the certificates were generated on a single node. The file is stored in the configuration directory of Cassandra in this example:
```
scp -r 10.200.175.150.jks /usr/local/lib/cassandra/conf/10.200.175.150.jks
```