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SSL : Theory and practice

The document outlines the establishment of the Open Source School in France, which aims to address the growing demand for skills in the open-source software sector supported by a government grant of €1.4 million. It offers a range of educational programs in open-source technologies for both initial training and continuing education, catering to the high number of unfilled positions in the field. The document also covers essential topics in cryptography and transport layer security (TLS), including the importance of public key infrastructure and secure communication methods.

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TLS / HTTPS Theory and practice
1 La 1ère école 100 % dédiée à l'open source Open Source School est fondée à l'initiative de Smile, leader de l'intégration et de l'infogérance open source, et de l'EPSI,établissement privé pionnier de l’enseignement supérieur en informatique. Dans le cadre du Programme d’Investissements d’Avenir (PIA), le gouvernement français a décidé de soutenir la création de cette école en lui attribuant une première aide de 1,4M€ et confirme sa volonté de soutenir la filière du Logiciel Libre actuellement en plein développement. Avec une croissance annuelle de plus de 10%, et 4 000 postes vacants chaque année dans le secteur du Logiciel Libre, OSS entend répondre à la pénurie de compétences du secteur en mobilisant l’ensemble de l’écosystème et en proposant la plus vaste offre en matière de formation aux technologies open source tant en formation initiale qu'en formation continue.
2 Les formations du plein emploi !  Formation Continue Open Source School "Executive Education" est un organisme de formation qui propose un catalogue de plus de 200 formations professionnelles et différents dispositifs de reconversion permettant le retour à l’emploi (POE) ou une meilleure employabilité pour de nombreux professionnels de l’informatique.  Pour vos demandes : formations@opensourceschool.fr  Formation Initiale 100% logiciels libres et 100% alternance, le cursus Open Source School s’appuie sur le référentiel des blocs de compétences de l’EPSI. Il est sanctionné par un titre de niveau I RNCP, Bac+5. Le programme est proposé dans 6 campus à Bordeaux, Lille, Lyon, Montpellier, Nantes, Paris.
3 Nos domaines de formations
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Introduction to cryptography www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 2/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Context Context www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 3/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Context Context The context : the Web is intrinsically an insecure medium relatively easy to listen to a communication: eavesdropping no certification of identity of both ends of the communication: spoofing no validation that the content has not been tampered: MitM injection Not so good for banking, eCommerce, medical applications... A combination of technologies is used to answer these questions, based on TLS and X509. www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 4/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Shared secret cryptography Shared secret cryptography www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 5/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Shared secret cryptography Shared secret cryptography Bob and Alice use the same secret to encrypt and decrypt the data Problem : the secret has to be communicated with both parties meeting in person to avoid compromise of secret higher risk of leaking as two parties know the secret even higher risk when communicating with more people Insecure and unpractical in a web context www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 6/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Public key cryptography www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 7/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography A Postal Analogy Alice wants to send a message to Bob Bob sends his lock to Alice The lock can be send via a normal postal service, as it cannot be easily used to create the matching key Alice send a message in a box locked with Bob’s key Not one else than Bob can open the box, as he is the only one with the key The box can be send over the normal postal service, as the mailman cannot open the box Public key cryptography The lock is the public key, as everyone can use it to lock the box. The lock’s key is the private key, as only the message receiver (Bob) can open the box www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 8/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Asymmetric keys Principle What is encrypted by the public key can only be decrypted by the private key What is encrypted by the private key can only be decrypted by the public key Public key are shared between the two ends of the communication. Bob knows Alice’s public key and Alice knows Bob public key. Everybody can have and use the public key without compromising the communication confidentiality www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 9/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Proving origin and integrity Confidentiality DOES NOT guaranty origin or integrity But public key cryptography can Using Alice’s private key to encrypt a (possibly encrypted) message proves that she wrote it Hash functions can help with integrity www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 10/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Message signing www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 11/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Message verification www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 12/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Remember Hash ensures integrity Encryption with the emitter’s private key ensures origin Encryption with the recipient’s public key ensures confidentiality www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 13/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Drawbacks very computationally intensive too costly to use for real time communication Solution: hybrid crypto-systems a symmetric key is generated before each exchange this key is exchanged with public key cryptography once the symmetric key has been exchanged, both system use it to encrypt and decrypt data www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 14/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Trust and the internet Trust and the internet www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 15/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Trust and the internet Trust and the internet The previously described system made a big asumption Alice’s public key belongs to Alice But what if Mallory sent you her public key, telling you it was Alice’s ? How to trust the identity of somebody you don’t know, or meet in person ? How to trust a website ? How to be sure a DNS requested has not been spoofed, or even the domain name stolen ? maybe mybank.com is really fakebank.hacker.ru. . . www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 16/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Trust and the internet Trusted third party EVERY. SINGLE. secure identification system in the world is based at some level on a trusted third party It can be very strict and hierarchical (X509) It can be loose and unstructured (Web of trust, PGP. . . ) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 17/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Trust and the internet Conclusion Securing a communication channel through the internet means : Validating the origin through a third party (X.509) Exchange a secure session key (TLS) Communicate through symmetric encryption (TLS) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 18/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Transport Layer Security www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 19/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca History History www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 20/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca History History SSL : Secure Socket Layer created by Netscape in 1995 last version : 3.0, 1999 insecure as of 2014 (POODLE) TLS : Transport Layer Security based on SSL 3.0 standardized by the RFC 2246 last version : 1.2, 2008 Since 2016, SSL and early versions of TLS are considered deprecated. TLS 1.2 is the only protocol that should be used. TLS is often erroneously called SSL www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 21/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca STARTTLS STARTTLS www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 22/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca STARTTLS STARTTLS Regular TLS connections use a dedicated port (80 vs 443) the communication is encrypted from the beginning to the end. if you need unencrypted and encrypted communications, two ports are necessary TLS allows security to be negociated mid-communication only one port is needed and is capable to have both unencrypted and encrypted communications but this is optional HTTP does not use IMAP, LDAP, do both (“old” SSL mode vs STARTTLS) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 23/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Algorithms Algorithms www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 24/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Algorithms Algorithms Auto-negociated Main source of non-certificate problems, although they are rare Troubleshooting = disable problematic algorithms www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 25/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Algorithms Algorithms - state of the art in 2013 NSA Suite (best) encryption AES256-GCM, AES256-CTR signature ECDSA hash SHA256, SHA384 key exchange ECDH Previous generation encryption AES-CBC signature RSA, DSA hash SHA1 key exchange DH Alternatives encryption CAMELLIA, BLOWFISH hash WHIRLPOOL, RIPEMD160 Insecure encryption RC4 (ArcFour), 3DES, DES hash MD5, MD4 www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 26/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca X509 certificates www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 27/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust Chain of trust www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 28/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust Content of a certificate A trusted certification authority is used to asymmetrically sign a website public key into a digital certificate A Digital Certificate contains entity public key Metadata : subject (what this certificate is for) certificate issuer (CA) certificate validity dates etc. (usually constraints) A signature : crypt(hash(key+meta),issuer private key) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 29/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust X509 Certification chain A CA can be signed by an other CA this is the certificate chain of trust The chain is hierarchical The CA at the top (or bottom of the tree) is the ”root certification authority The trust is transmitted from the root certification authority to the highest level certificate : the website one www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 30/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust X509 Root Certificates Locally stored ! in opposition to non-root CA certificates and website certificate that are provided directly by the website Can be provided by the browser by the OS by the JVM Root CA must be well known and established (Verisign, GoDaddy, Thawte, etc. . . ) be secured: stealing the private key of a CA means end of business for a root CA (Diginotar) undergo audit from entity like WebTrust www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 31/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust X509 Root certificate storage In the browser Preferences -> Advanced -> Encryption -> View certificates The OpenSSL storage /etc/ssl/certs (in Debian) The JVM storage <jre path>lib/security/cacerts www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 32/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca X509 and TLS X509 and TLS www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 33/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca X509 and TLS HTTPS Handshake The client connects to a server and announces supported ciphers The server chooses the strongest cipher and sends its certificate The clients now has the servers public key, and proof (via the signature) that it is authentic (simplified : ) the client generates the session key, encrypts it with the server’s pubkey, and sends it to the server From now on, every communication is secured using a session key that has been accepted by the two parties www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 34/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice Practice www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 35/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice HTTPS Handshake Handshaking openssl s client -showcerts -host <myhost> -port 443 With locally stored certificate (Debian) openssl s client -showcerts -h <myhost> -p 443 -CApath /etc/ssl/certs/ The CN of the certificate must be equals to the domain name used to access the website www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 36/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice Decoding a certificate Copy and paste from the previous OpenSSL command, between BEGIN CERTIFICATE and END CERTIFICATE, included openssl x509 -in <file.pem> -text Certificate formats by default : PEM format DER (PEM is simply base64 encoded DER) can be used by OpenSSL and Java (keytool) indifferently PKCS#12, PKCS#7 (often used for client certificate) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 37/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice How to create a certificate What do we need ? a public and private keys pair an authority to sign our public key and generate our certificate www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 38/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice How to create a certificate - Public/private key pair Create a public/private key pair openssl genrsa -out <mykey> 2048 www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 39/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice How to create a certificate - CSR Create a certificate signing request (CSR) by providing all the data of the certificate openssl req -new -key <mykey> -out <myserver.csr> be careful : CN = domain name used to access the server www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 40/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice How to create a certificate - Signature Create the certificate by signing the data provided by the certificate request either send it to the CA either signed it with your own key self signed certificate openssl x509 -req -days <validity> -in <myserver.csr> -signkey <mykey> -out <myserver.crt> www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 41/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice Apache configuration In the 443 port-based VirtualHost SSLEngine on SSLCertificateFile <myserver.crt> SSLCertificateKeyFile <mykey.key> SSLCertificateChainFile <mychain.pem> Note : usually, put the <myserver.crt> and <mykey> files in the /etc/apache2/ssl/ directory, only accessible by root www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 42/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice HTTPS and VirtualHost by Name The name of the virtualhost is inside the HTTP Host header The HTTP headers are inside the encrypted communication The communication is encrypted using the public key that contains the hostname. . . Apache cannot select a certificate if several VirtualHost by name with different certificate are configured Solutions wildcard certificate : *.smile.fr use the X509 alternative name extensions : several CN can be used inside one certificate Server Name Indication (SNI) : a TLS extension that sends the VirtualHost name as part of the TLS handshake. Only works on recent clients and server : Debian Squeeze, Windows Vista+IE7 www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 43/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Java and TLS Java and TLS www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 44/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Java and TLS Keytool Much more basic than openssl tools Should not be used to generate production certificate no support for X509v3 extensions Certificates are stored inside keystore Listing a keystore content keytool -list -v -keystore <mykeystore> Export them to use them outside the Java world keytool -exportcert -keystore <mykeystore> -alias -file <mycert> Displaying certificate content keytool -printcert -file <cert> www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 45/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Java and TLS Keystore <jre root>/lib/security/cacerts standard Java Keystore password: changeit Importing certificate into cacerts keytool -importcert -alias <myCertAlias> -file <myCaFile> -keystore cacerts www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 46/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Java and TLS Debugging Use the SSLTest program (in formation/https/programs) to access intranet.smile.fr java -cp . SSLTest intranet.smile.fr 443 Use “ssl” for the javax.net.debug property java -Djavax.net.debug=ssl www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 47/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Certificate Authorities with Ope www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 48/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Configuring the CA Configuring the CA www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 49/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Configuring the CA Configuring the CA Create a section at the end of /etc/ssl/openssl.cnf [ my ca ] d i r = /home/ formation /my ca database = $ d i r / index . t x t n e w c e r t s d i r = $ d i r / newcerts c e r t i f i c a t e = $ d i r / c a c e r t . pem s e r i a l = $ d i r / s e r i a l p r i v a t e k e y = $ d i r / p r i v a t e / cakey . pem RANDFILE = $ d i r / p r i v a t e /. rand d e f a u l t d a y s = 365 d e f a u l t c r l d a y s= 30 default md = md5 p o l i c y = p o l i c y a n y t h i n g e m a i l i n d n = no name opt = c a d e f a u l t c e r t o p t = c a d e f a u l t c o p y e x t e n s i o n s = none www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 50/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Creating the CA key Creating the CA key www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 51/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Creating the CA key Creating the CA key Create the requires folders : mkdir /home/formation/my ca mkdir /home/formation/my ca/private mkdir /home/formation/my ca/newcerts touch /home/formation/my ca/index.txt echo 01 > /home/formation/my ca/serial openssl req -new -x509 -days 3650 -extensions v3 ca -keyout /home/formation/my ca/private/cakey.pem -out /home/formation/my ca/cacert.pem the -extensions switch specify which section in /etc/ssl/openssl.cnf must be applied A root CA is self-signed www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 52/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Creating a server certificate Creating a server certificate www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 53/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Creating a server certificate Creating a server certificate Signing the CSR with the CA openssl ca -in myserver.csr -name my ca -out myserver.cert Importing the CA in the browser In Firefox: Preferences -> Advanced -> View certificates -> Authorities -> Import. . . In Internet Explorer Windows : Manage Root Certificate www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 54/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Client authentication Client authentication www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 55/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Client authentication Creating a client certificate Almost the same thing as a server certificate When generating the key Add a password to the key (-des3) to avoid unauthorized use When generating the CSR Add the -extensions usr cert switch to the command line Then sign it with the CA key To be used in a browser, must be exported to p12 format openssl pkcs12 -export -in client.crt -inkey client.key -out client.p12 Specify an export password to avoid people extracting your certificate from your browser Now import it in “Your Certificates” www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 56/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Client authentication Client authentication with Apache SSLOptions +StdEnvVars SSLVerifyClient require SSLCACertificateFile /etc/apache2/myCA.cert Authentication and identification are done by Apache via the certificate SSO with client certificate each application can read data provided by the certificate the user does not need to enter password www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 57/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Revocation www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 58/59
Introduction to cryptography Transport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Certificate Revocation List specify with certificate should be revocated use openssl ca to manage them Online Certificate Status Protocol tell the browser where it can find the revocation status of a certificate www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 59/59

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SOFTWARE DEVELOPMENT PROCESS - INTRODUCTION
byParithi Thamizh
 

SSL : Theory and practice

  • 1.
    TLS / HTTPS Theoryand practice
  • 2.
    1 La 1ère école100 % dédiée à l'open source Open Source School est fondée à l'initiative de Smile, leader de l'intégration et de l'infogérance open source, et de l'EPSI,établissement privé pionnier de l’enseignement supérieur en informatique. Dans le cadre du Programme d’Investissements d’Avenir (PIA), le gouvernement français a décidé de soutenir la création de cette école en lui attribuant une première aide de 1,4M€ et confirme sa volonté de soutenir la filière du Logiciel Libre actuellement en plein développement. Avec une croissance annuelle de plus de 10%, et 4 000 postes vacants chaque année dans le secteur du Logiciel Libre, OSS entend répondre à la pénurie de compétences du secteur en mobilisant l’ensemble de l’écosystème et en proposant la plus vaste offre en matière de formation aux technologies open source tant en formation initiale qu'en formation continue.
  • 3.
    2 Les formations duplein emploi !  Formation Continue Open Source School "Executive Education" est un organisme de formation qui propose un catalogue de plus de 200 formations professionnelles et différents dispositifs de reconversion permettant le retour à l’emploi (POE) ou une meilleure employabilité pour de nombreux professionnels de l’informatique.  Pour vos demandes : formations@opensourceschool.fr  Formation Initiale 100% logiciels libres et 100% alternance, le cursus Open Source School s’appuie sur le référentiel des blocs de compétences de l’EPSI. Il est sanctionné par un titre de niveau I RNCP, Bac+5. Le programme est proposé dans 6 campus à Bordeaux, Lille, Lyon, Montpellier, Nantes, Paris.
  • 4.
  • 5.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Introduction to cryptography www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 2/59
  • 6.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Context Context www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 3/59
  • 7.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Context Context The context : the Web is intrinsically an insecure medium relatively easy to listen to a communication: eavesdropping no certification of identity of both ends of the communication: spoofing no validation that the content has not been tampered: MitM injection Not so good for banking, eCommerce, medical applications... A combination of technologies is used to answer these questions, based on TLS and X509. www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 4/59
  • 8.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Shared secret cryptography Shared secret cryptography www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 5/59
  • 9.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Shared secret cryptography Shared secret cryptography Bob and Alice use the same secret to encrypt and decrypt the data Problem : the secret has to be communicated with both parties meeting in person to avoid compromise of secret higher risk of leaking as two parties know the secret even higher risk when communicating with more people Insecure and unpractical in a web context www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 6/59
  • 10.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Public key cryptography www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 7/59
  • 11.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography A Postal Analogy Alice wants to send a message to Bob Bob sends his lock to Alice The lock can be send via a normal postal service, as it cannot be easily used to create the matching key Alice send a message in a box locked with Bob’s key Not one else than Bob can open the box, as he is the only one with the key The box can be send over the normal postal service, as the mailman cannot open the box Public key cryptography The lock is the public key, as everyone can use it to lock the box. The lock’s key is the private key, as only the message receiver (Bob) can open the box www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 8/59
  • 12.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Asymmetric keys Principle What is encrypted by the public key can only be decrypted by the private key What is encrypted by the private key can only be decrypted by the public key Public key are shared between the two ends of the communication. Bob knows Alice’s public key and Alice knows Bob public key. Everybody can have and use the public key without compromising the communication confidentiality www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 9/59
  • 13.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Proving origin and integrity Confidentiality DOES NOT guaranty origin or integrity But public key cryptography can Using Alice’s private key to encrypt a (possibly encrypted) message proves that she wrote it Hash functions can help with integrity www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 10/59
  • 14.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Message signing www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 11/59
  • 15.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Message verification www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 12/59
  • 16.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Remember Hash ensures integrity Encryption with the emitter’s private key ensures origin Encryption with the recipient’s public key ensures confidentiality www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 13/59
  • 17.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Public key cryptography Drawbacks very computationally intensive too costly to use for real time communication Solution: hybrid crypto-systems a symmetric key is generated before each exchange this key is exchanged with public key cryptography once the symmetric key has been exchanged, both system use it to encrypt and decrypt data www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 14/59
  • 18.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Trust and the internet Trust and the internet www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 15/59
  • 19.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Trust and the internet Trust and the internet The previously described system made a big asumption Alice’s public key belongs to Alice But what if Mallory sent you her public key, telling you it was Alice’s ? How to trust the identity of somebody you don’t know, or meet in person ? How to trust a website ? How to be sure a DNS requested has not been spoofed, or even the domain name stolen ? maybe mybank.com is really fakebank.hacker.ru. . . www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 16/59
  • 20.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Trust and the internet Trusted third party EVERY. SINGLE. secure identification system in the world is based at some level on a trusted third party It can be very strict and hierarchical (X509) It can be loose and unstructured (Web of trust, PGP. . . ) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 17/59
  • 21.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Trust and the internet Conclusion Securing a communication channel through the internet means : Validating the origin through a third party (X.509) Exchange a secure session key (TLS) Communicate through symmetric encryption (TLS) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 18/59
  • 22.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Transport Layer Security www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 19/59
  • 23.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca History History www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 20/59
  • 24.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca History History SSL : Secure Socket Layer created by Netscape in 1995 last version : 3.0, 1999 insecure as of 2014 (POODLE) TLS : Transport Layer Security based on SSL 3.0 standardized by the RFC 2246 last version : 1.2, 2008 Since 2016, SSL and early versions of TLS are considered deprecated. TLS 1.2 is the only protocol that should be used. TLS is often erroneously called SSL www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 21/59
  • 25.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca STARTTLS STARTTLS www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 22/59
  • 26.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca STARTTLS STARTTLS Regular TLS connections use a dedicated port (80 vs 443) the communication is encrypted from the beginning to the end. if you need unencrypted and encrypted communications, two ports are necessary TLS allows security to be negociated mid-communication only one port is needed and is capable to have both unencrypted and encrypted communications but this is optional HTTP does not use IMAP, LDAP, do both (“old” SSL mode vs STARTTLS) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 23/59
  • 27.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Algorithms Algorithms www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 24/59
  • 28.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Algorithms Algorithms Auto-negociated Main source of non-certificate problems, although they are rare Troubleshooting = disable problematic algorithms www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 25/59
  • 29.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Algorithms Algorithms - state of the art in 2013 NSA Suite (best) encryption AES256-GCM, AES256-CTR signature ECDSA hash SHA256, SHA384 key exchange ECDH Previous generation encryption AES-CBC signature RSA, DSA hash SHA1 key exchange DH Alternatives encryption CAMELLIA, BLOWFISH hash WHIRLPOOL, RIPEMD160 Insecure encryption RC4 (ArcFour), 3DES, DES hash MD5, MD4 www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 26/59
  • 30.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca X509 certificates www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 27/59
  • 31.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust Chain of trust www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 28/59
  • 32.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust Content of a certificate A trusted certification authority is used to asymmetrically sign a website public key into a digital certificate A Digital Certificate contains entity public key Metadata : subject (what this certificate is for) certificate issuer (CA) certificate validity dates etc. (usually constraints) A signature : crypt(hash(key+meta),issuer private key) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 29/59
  • 33.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust X509 Certification chain A CA can be signed by an other CA this is the certificate chain of trust The chain is hierarchical The CA at the top (or bottom of the tree) is the ”root certification authority The trust is transmitted from the root certification authority to the highest level certificate : the website one www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 30/59
  • 34.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust X509 Root Certificates Locally stored ! in opposition to non-root CA certificates and website certificate that are provided directly by the website Can be provided by the browser by the OS by the JVM Root CA must be well known and established (Verisign, GoDaddy, Thawte, etc. . . ) be secured: stealing the private key of a CA means end of business for a root CA (Diginotar) undergo audit from entity like WebTrust www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 31/59
  • 35.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Chain of trust X509 Root certificate storage In the browser Preferences -> Advanced -> Encryption -> View certificates The OpenSSL storage /etc/ssl/certs (in Debian) The JVM storage <jre path>lib/security/cacerts www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 32/59
  • 36.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca X509 and TLS X509 and TLS www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 33/59
  • 37.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca X509 and TLS HTTPS Handshake The client connects to a server and announces supported ciphers The server chooses the strongest cipher and sends its certificate The clients now has the servers public key, and proof (via the signature) that it is authentic (simplified : ) the client generates the session key, encrypts it with the server’s pubkey, and sends it to the server From now on, every communication is secured using a session key that has been accepted by the two parties www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 34/59
  • 38.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice Practice www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 35/59
  • 39.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice HTTPS Handshake Handshaking openssl s client -showcerts -host <myhost> -port 443 With locally stored certificate (Debian) openssl s client -showcerts -h <myhost> -p 443 -CApath /etc/ssl/certs/ The CN of the certificate must be equals to the domain name used to access the website www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 36/59
  • 40.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice Decoding a certificate Copy and paste from the previous OpenSSL command, between BEGIN CERTIFICATE and END CERTIFICATE, included openssl x509 -in <file.pem> -text Certificate formats by default : PEM format DER (PEM is simply base64 encoded DER) can be used by OpenSSL and Java (keytool) indifferently PKCS#12, PKCS#7 (often used for client certificate) www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 37/59
  • 41.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice How to create a certificate What do we need ? a public and private keys pair an authority to sign our public key and generate our certificate www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 38/59
  • 42.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice How to create a certificate - Public/private key pair Create a public/private key pair openssl genrsa -out <mykey> 2048 www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 39/59
  • 43.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice How to create a certificate - CSR Create a certificate signing request (CSR) by providing all the data of the certificate openssl req -new -key <mykey> -out <myserver.csr> be careful : CN = domain name used to access the server www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 40/59
  • 44.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice How to create a certificate - Signature Create the certificate by signing the data provided by the certificate request either send it to the CA either signed it with your own key self signed certificate openssl x509 -req -days <validity> -in <myserver.csr> -signkey <mykey> -out <myserver.crt> www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 41/59
  • 45.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice Apache configuration In the 443 port-based VirtualHost SSLEngine on SSLCertificateFile <myserver.crt> SSLCertificateKeyFile <mykey.key> SSLCertificateChainFile <mychain.pem> Note : usually, put the <myserver.crt> and <mykey> files in the /etc/apache2/ssl/ directory, only accessible by root www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 42/59
  • 46.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Practice HTTPS and VirtualHost by Name The name of the virtualhost is inside the HTTP Host header The HTTP headers are inside the encrypted communication The communication is encrypted using the public key that contains the hostname. . . Apache cannot select a certificate if several VirtualHost by name with different certificate are configured Solutions wildcard certificate : *.smile.fr use the X509 alternative name extensions : several CN can be used inside one certificate Server Name Indication (SNI) : a TLS extension that sends the VirtualHost name as part of the TLS handshake. Only works on recent clients and server : Debian Squeeze, Windows Vista+IE7 www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 43/59
  • 47.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Java and TLS Java and TLS www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 44/59
  • 48.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Java and TLS Keytool Much more basic than openssl tools Should not be used to generate production certificate no support for X509v3 extensions Certificates are stored inside keystore Listing a keystore content keytool -list -v -keystore <mykeystore> Export them to use them outside the Java world keytool -exportcert -keystore <mykeystore> -alias -file <mycert> Displaying certificate content keytool -printcert -file <cert> www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 45/59
  • 49.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Java and TLS Keystore <jre root>/lib/security/cacerts standard Java Keystore password: changeit Importing certificate into cacerts keytool -importcert -alias <myCertAlias> -file <myCaFile> -keystore cacerts www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 46/59
  • 50.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Java and TLS Debugging Use the SSLTest program (in formation/https/programs) to access intranet.smile.fr java -cp . SSLTest intranet.smile.fr 443 Use “ssl” for the javax.net.debug property java -Djavax.net.debug=ssl www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 47/59
  • 51.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Certificate Authorities with Ope www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 48/59
  • 52.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Configuring the CA Configuring the CA www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 49/59
  • 53.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Configuring the CA Configuring the CA Create a section at the end of /etc/ssl/openssl.cnf [ my ca ] d i r = /home/ formation /my ca database = $ d i r / index . t x t n e w c e r t s d i r = $ d i r / newcerts c e r t i f i c a t e = $ d i r / c a c e r t . pem s e r i a l = $ d i r / s e r i a l p r i v a t e k e y = $ d i r / p r i v a t e / cakey . pem RANDFILE = $ d i r / p r i v a t e /. rand d e f a u l t d a y s = 365 d e f a u l t c r l d a y s= 30 default md = md5 p o l i c y = p o l i c y a n y t h i n g e m a i l i n d n = no name opt = c a d e f a u l t c e r t o p t = c a d e f a u l t c o p y e x t e n s i o n s = none www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 50/59
  • 54.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Creating the CA key Creating the CA key www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 51/59
  • 55.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Creating the CA key Creating the CA key Create the requires folders : mkdir /home/formation/my ca mkdir /home/formation/my ca/private mkdir /home/formation/my ca/newcerts touch /home/formation/my ca/index.txt echo 01 > /home/formation/my ca/serial openssl req -new -x509 -days 3650 -extensions v3 ca -keyout /home/formation/my ca/private/cakey.pem -out /home/formation/my ca/cacert.pem the -extensions switch specify which section in /etc/ssl/openssl.cnf must be applied A root CA is self-signed www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 52/59
  • 56.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Creating a server certificate Creating a server certificate www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 53/59
  • 57.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Creating a server certificate Creating a server certificate Signing the CSR with the CA openssl ca -in myserver.csr -name my ca -out myserver.cert Importing the CA in the browser In Firefox: Preferences -> Advanced -> View certificates -> Authorities -> Import. . . In Internet Explorer Windows : Manage Root Certificate www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 54/59
  • 58.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Client authentication Client authentication www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 55/59
  • 59.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Client authentication Creating a client certificate Almost the same thing as a server certificate When generating the key Add a password to the key (-des3) to avoid unauthorized use When generating the CSR Add the -extensions usr cert switch to the command line Then sign it with the CA key To be used in a browser, must be exported to p12 format openssl pkcs12 -export -in client.crt -inkey client.key -out client.p12 Specify an export password to avoid people extracting your certificate from your browser Now import it in “Your Certificates” www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 56/59
  • 60.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Client authentication Client authentication with Apache SSLOptions +StdEnvVars SSLVerifyClient require SSLCACertificateFile /etc/apache2/myCA.cert Authentication and identification are done by Apache via the certificate SSO with client certificate each application can read data provided by the certificate the user does not need to enter password www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 57/59
  • 61.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Revocation www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 58/59
  • 62.
    Introduction to cryptographyTransport Layer Security X509 certificates Certificate Authorities with OpenSSL Revoca Certificate Revocation List specify with certificate should be revocated use openssl ca to manage them Online Certificate Status Protocol tell the browser where it can find the revocation status of a certificate www.opensourceschool.fr – Licence Creative Commons (CC BY-SA 3.0 FR) – 59/59