x509-authentication

Spring Security X.509 Certificate Based Authentication

Instead of Password based challenge, the server identifies client using their certificate.

Table of Contents

• Certificate Generation and Usage
• Contents in Key Store and Truststore
• TCP Dump and Analysis

Created by Alok Singh

Certificate Generation and Usage

1. Root Certificate

    openssl req -x509 -sha256 -days 3650 -newkey rsa:4096 -keyout rootCA_Alok.key -out rootCA_Alok.crt
    
    Pwd: changeit
    generates: 
    	rootCA_Alok.key
    	rootCA_Alok.crt
   

2. Server Side Certificate - this will be used by Spring Boot Server

   2.1) Generate Server Side Certificate

    openssl req -new -newkey rsa:4096 -keyout localhost.key -out localhost.csr
   
    Country Name (2 letter code) []:IN
    State or Province Name (full name) []:KA
    Locality Name (eg, city) []:BLR
    Organization Name (eg, company) []:Home
    Organizational Unit Name (eg, section) []:Abc
    Common Name (eg, fully qualified host name) []:localhost
    Email Address []:alok.ku.singh@gmail.com
   
    Please enter the following 'extra' attributes
    to be sent with your certificate request
    A challenge password []:
   
    generates:
    	localhost.key
    	localhost.csr
   

   2.2) Sign Cert with Alok Root:

    vim localhost.ext
    authorityKeyIdentifier=keyid,issuer
    basicConstraints=CA:FALSE
    subjectAltName = @alt_names
    [alt_names]
    DNS.1 = localhost
   
    openssl x509 -req -CA rootCA_Alok.crt -CAkey rootCA_Alok.key -in localhost.csr -out localhost.crt -days 365 -CAcreateserial -extfile localhost.ext
    generates:
    	rootCA_Alok.srl
    	localhost.crt
   

   2.3) Import to Keystore:

    1st) Add the loaclhost.key and loaclhost.crt in single PKCS 12 bundle:
    	
    	openssl pkcs12 -export -out localhost.p12 -name "localhost" -inkey localhost.key -in localhost.crt
    	Pwd: <password and remeber for furture use>
    	generates:
    		localhost.p12
   
    2nd) Import PKCS bundle to JKS
    	
    	keytool -importkeystore -srckeystore localhost.p12 -srcstoretype PKCS12 -destkeystore keystore.jks -deststoretype JKS
    	Pwd: <password and remeber for furture use>
    	generates:
    		keystore.jks
   

3. Import Root CA cert to browser as Authority certificate - so that browser trust cert which is signed using this Root Cert (no risk warning will be shown in the browser)

    An exemplary installation of our certificate authority for Mozilla Firefox would look like follows:
   
    Type about:preferences in the address bar
    Open Advanced -> Certificates -> View Certificates -> Authorities
    Click on Import
    Select rootCA_Alok.crt file and click OK
    Choose “Trust this CA to identify websites” and click OK
   

4. Create Trust Store and Import Root CA cert which is used to sign Client Certificate - so that server trusts certificate signed using the same Root CA certificate:

    keytool -import -trustcacerts -noprompt -alias ca -ext san=dns:localhost,ip:127.0.0.1 -file rootCA_Alok.crt -keystore truststore.jks
    Pwd: <password and remeber for furture use>
    generates: truststore.jks
   

5. Create Client Certificate for Alok and Sign using RootCA_Alok so that server trusts

   Server Says: I dont trust "Client Alok" (since Alok certificate is not addded in JKS) but I do trust "Root CA Alok" and he trusts you so do I.

   5.1) Generate Client Key and CSR

    openssl req -new -newkey rsa:4096 -nodes -keyout clientAlok.key -out clientAlok.csr
    Pwd: no password
    generates:
    	clientAlok.key
    	clientAlok.csr
   

   5.2) Sign cert for Alok with RootCA_Alok:

    openssl x509 -req -CA rootCA_Alok.crt -CAkey rootCA_Alok.key -in clientAlok.csr -out clientAlok.crt -days 365 -CAcreateserial
    generates: 
    	clientAlok.crt
   

   5.3) Import cert to PKCS Bundle:

    openssl pkcs12 -export -out clientAlok.p12 -name "clientAlok" -inkey clientAlok.key -in clientAlok.crt
    Pwd: No password
    generates:
    	clientAlok.p12
   

6. Import Alok Client Cert (clientAlok.p12) to browser - so that when communicating to localhost this certificate will be sent for Authentication:

    Type about:preferences in the address bar
    Open Advanced -> View Certificates -> Your Certificates
    Click on Import
    Select clientAlok.p12 file and click OK
    Input the password for your certificate and click OK
   

7. Hit the Secure URL

   7.1) Using Firefox

    https://localhost:8443/user
    
    It will promt to select one of the installed client certificate in the Browser
   

   7.2) Hit the API URL using CURL

    curl --cacert rootCA_Alok.crt --key clientAlok.key --cert clientAlok.crt https://localhost:8443/api/user
    
    Where:
    	cacert: Root CA Cert who signed server certificate (substitute of step 3)
    	key: Client Key (substitute of step 6)
    	cert: Client Certificate (substitute of step 6)
    	
    Note: for this step you may skip steps - 3, 5.3, and 6 (above)
   

Contents in Key Store and Truststore

1. Key Store

   • localhost.key
   • localhost.crt

2. Trust Store

   • rootCA_Alok.crt

TCP Dump and Analysis

Find the dump file under dump/ folder. You may use Wiresark to read the dump file.

1. TCP Dump Command

sudo tcpdump -i lo0 -n -s0 -w /Users/aloksingh/logs/x509App_04.cap port 8443

Assuming lo0 is loopback interface.

2. Dump Analysis

   

   Note: The above screenshot is without decrypting the Application data. If you want to see the decrypted application data you need to extract pre_master_secret_key (symmetric key) from the dump using ssldump tool and pass the same key log file to Wireshark. So that Wireshark can decrypt the application dta using the symmetric key and show in here.

   • [C <-> S] First 4 packets is for TCP handshake
   • [C <-> S] 5 and 6 Client Hello and ACK from server
   • [C <-- S] 7 Server Hello along with Server Certificate, Server Key Exchange, Certificate Request (Mandatory for Mutual Authentication)
   • [C --> S] 8 ACK
   • [C --> S] 9 Client Certificate (Mandatory for Mutual Authentication) along with Client Key Exchange (for RSA, a 48-byte pre_master_secret (also known as session key) is generated by the client and encrypted using server public key, which can be decrypted only by private key server has), Certificate Verify, Change Cipher Spec (from now onwards to use symmetric key for encryption/decryption)
   • [C <-- S] 10 ACK
   • [C <-- S] 11 Change Cipher Spec (from now onwards to use symmetric key encryption/decryption - shared recently)
   • [C --> S] 12 ACK
   • [C <-- S] 13 Encrypted Handshake Message (Finished) - indicates TLS negotiations completed
   • [C --> S] 14 ACK
   • [C --> S] 15 GET request from Client
   • [C <-- S] 16 ACK
   • [C <-- S] 17 GET response from Server
   • [C --> S] 18 ACK
   • [C --> S] 19 Encrypted Alert
   • [C <-- S] 20 ACK
   • [C --> S] 21 FIN
   • [C <-- S] 22 ACK