The first few milliseconds of HTTPS

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The first few milliseconds of HTTPS 1 Joshua Thijssen JayTaph

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➡ What’s happening in the first 200+ milliseconds in a initial HTTPS connection. 2

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➡ What’s happening in the first 200+ milliseconds in a initial HTTPS connection. ➡ Give tips and hints on hardening your setup. 2

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➡ What’s happening in the first 200+ milliseconds in a initial HTTPS connection. ➡ Give tips and hints on hardening your setup. ➡ Give you insights in new and upcoming technologies. 2

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➡ What’s happening in the first 200+ milliseconds in a initial HTTPS connection. ➡ Give tips and hints on hardening your setup. ➡ Give you insights in new and upcoming technologies. ➡ Show you things to you (probably) didn’t knew. 2

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HTTPS == HTTP on top of TLS 3

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Transport Layer Security (TLS) 4

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Secure Socket Layer (SSL) 5 A short and scary history

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then now 6

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then now SSL 1.0 Vaporware 1994 6

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then now feb 1995 SSL 2.0 Not-so-secure-socket-layer SSL 1.0 Vaporware 1994 6

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then now feb 1995 SSL 2.0 Not-so-secure-socket-layer jun 1996 SSL 3.0 Something stable! SSL 1.0 Vaporware 1994 6

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then now feb 1995 SSL 2.0 Not-so-secure-socket-layer jun 1996 SSL 3.0 Something stable! jan 1999 TLS 1.0 SSL 3.1 SSL 1.0 Vaporware 1994 6

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then now feb 1995 SSL 2.0 Not-so-secure-socket-layer jun 1996 SSL 3.0 Something stable! jan 1999 TLS 1.0 SSL 3.1 apr 2006 TLS 1.1 SSL 1.0 Vaporware 1994 6

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then now feb 1995 SSL 2.0 Not-so-secure-socket-layer jun 1996 SSL 3.0 Something stable! jan 1999 TLS 1.0 SSL 3.1 apr 2006 TLS 1.1 TLS 1.2 aug 2008 SSL 1.0 Vaporware 1994 6

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https://www.trustworthyinternet.org/ssl-pulse/ 25,7% 99,6% 99,3% 18,2% 20,7% SSL 2.0 SSL 3.0 TLS 1.0 TLS 1.1 TLS 1.2 7 November 2013

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https://www.trustworthyinternet.org/ssl-pulse/ 25,7% 99,6% 99,3% 18,2% 20,7% SSL 2.0 SSL 3.0 TLS 1.0 TLS 1.1 TLS 1.2 7 November 2013 4,5% 15,6% 93,9% 83,6% 86,8% SSL 2.0 SSL 3.0 TLS 1.0 TLS 1.1 TLS 1.2 June 2017

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RFC 5246 (TLS v1.2) 9

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➡ Authenticate and exchange information. ➡ Exchange a key (through a public key system). ➡ Create "tunnel" with symmetric encryption (both sides use the same exchanged key). 10

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11 https://github.com/vincentbernat/rfc5077/blob/master/ssl-handshake.svg

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Attention: (live) wiresharking up ahead 12

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TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 14

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TLS ECDHE_ECDSA WITH AES_128_GCM SHA256 15

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TLS ECDHE_ECDSA WITH AES_128_GCM SHA256 Cipher for exchanging key information 15

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TLS ECDHE_ECDSA WITH AES_128_GCM SHA256 Cipher for exchanging key information Cipher for authenticating key information 15

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TLS ECDHE_ECDSA WITH AES_128_GCM SHA256 Cipher for exchanging key information Cipher for authenticating key information Actual cipher (and length) used for communication 15

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TLS ECDHE_ECDSA WITH AES_128_GCM SHA256 Cipher for exchanging key information Cipher for authenticating key information Hash algo for message authenticating Actual cipher (and length) used for communication 15

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TLS_RSA_WITH_AES_256_CBC_SHA256 16

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TLS_NULL_WITH_NULL_NULL 17

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Client gives cipher options, Server ultimately decides on cipher! 18

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THIS IS WHY YOU SHOULD ALWAYS CONFIGURE YOUR CIPHERS ON YOUR WEB SERVER! 19 Unknown fact!

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20 https://cipherli.st Gives you strong cipher configuration webservers (apache,nginx etc) and other software.

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https://www.ssllabs.com/ssltest/ 21

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23 ➡ SNI (Server Name Indication) ➡ Extension 0x0000 ➡ Pretty much every decent browser / server / os ➡ Except: IE6, Win XP, Blackberry, Android 2.x, java 1.6.x

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What an SSL certificate is NOT: 25 ➡ SSL certificate (but a X.509 certificate) ➡ Automatically secure ➡ Automatically trustworthy ➡ In any way better self-signed certificates ➡ Cheap

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What an SSL certificate is: 26 ➡ The best way (but not perfect) to prove authenticity ➡ A way to bootstrap encrypted communication ➡ Misleading ➡ (Too) Expensive

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Certificate: Data: Version: 3 (0x2) Serial Number: 0c:00:93:10:d2:06:db:e3:37:55:35:80:11:8d:dc:87 Signature Algorithm: sha256WithRSAEncryption Issuer: C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert SHA2 Extended Validation Server CA Validity Not Before: Apr 8 00:00:00 2014 GMT Not After : Apr 12 12:00:00 2016 GMT Subject: ... C=US, ST=California, L=San Francisco, O=GitHub, Inc., CN=github.com Subject Public Key Info: Public Key Algorithm: rsaEncryption Public-Key: (2048 bit) Modulus: 00:b1:d4:dc:3c:af:fd:f3:4e:ed:c1:67:ad:e6:cb: 22:e8:b7:e2:ab:28:f2:f7:dc:62:70:08:d1:0c:af: ....... 67:8d Exponent: 65537 (0x10001) X509v3 extensions: X509v3 Subject Alternative Name: DNS:github.com, DNS:www.github.com X509v3 Key Usage: critical Digital Signature, Key Encipherment X509v3 Extended Key Usage: TLS Web Server Authentication, TLS Web Client Authentication X509v3 Basic Constraints: critical CA:FALSE Signature Algorithm: sha256WithRSAEncryption 6f:e7:6d:cb:82:f3:ef:90:87:09:d7:0f:15:22:2c:8c:fe:d3: ab:1c:8a:96:db:5d:12:5d:d1:78:c0:31:b0:ff:45:c8:89:f7: 08:98:52:17:1f:4c:4b:20:64:6a:6d:db:50:d7:10:be:7e:ab: ...... ee:b7:33:69 27

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28 yourdomain.com

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28 yourdomain.com Intermediate CA

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28 yourdomain.com Intermediate CA

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28 yourdomain.com Root CA Intermediate CA

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28 yourdomain.com Root CA Intermediate CA

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28 yourdomain.com Root CA Intermediate CA

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29 IMPLIED TRU$T

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➡ (Root) Certificate Authorities ➡ They are built into your browser / OS and you will automatically trust them. 30

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31 wget http://mxr.mozilla.org/mozilla-central/source/security/nss/lib/ckfw/builtins/certdata.txt\?raw\=1 -O - -q | grep Issuer | sort | uniq | wc -l

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31 wget http://mxr.mozilla.org/mozilla-central/source/security/nss/lib/ckfw/builtins/certdata.txt\?raw\=1 -O - -q | grep Issuer | sort | uniq | wc -l 181 And rising...

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32 ➡ X.509 certificates are used to authenticate the server.

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32 ➡ X.509 certificates are used to authenticate the server. ➡ Servers can ask clients to authenticate themselves as well.

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32 ➡ X.509 certificates are used to authenticate the server. ➡ Servers can ask clients to authenticate themselves as well. ➡ APIs

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Sending over our initial secret data 33

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➡ Client generates random key (pre-shared key). ➡ Client encrypts key with public key from server SSL certificate. ➡ Client sends encrypted key to server. ➡ Server decrypts key with private key. 34 RSA

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➡ Server generates key pair ➡ Server sends public key to client, with signature to prove authenticity (pub key from SSL certificate) ➡ Client generates key pair ➡ Client sends public key to server ➡ Both server and client calculate "secret". 35 (Elliptic curve) Difﬁe-Hellman (ephemeral)

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37 Generating secrets:

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37 pre master secret Generating secrets:

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37 pre master secret server rand client rand Generating secrets: + +

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37 pre master secret server rand client rand master secret Generating secrets: + +

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37 pre master secret server rand client rand master secret master secret server rand client rand Generating secrets: + + + +

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37 pre master secret server rand client rand master secret master secret server rand client rand key buffer Generating secrets: + + + +

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37 pre master secret server rand client rand master secret client MAC client KEY client IV server MAC server KEY server IV master secret server rand client rand key buffer Generating secrets: + + + +

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https://github.com/jaytaph/TLS-decoder 38 http://www.adayinthelifeof.nl/2013/12/30/decoding-tls-with-php/ Try it yourself, php style:

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42 Wireshark CAN decrypt your HTTPS trafﬁc Unknown fact! SSLKEYLOGFILE https://isc.sans.edu/forums/diary/Psst+Your+Browser+Knows+All+Your+Secrets+/16415

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43 launchctl setenv SSLKEYLOGFILE /tmp/keylog.secret on a mac:

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-ETOOMUCHINFO 44

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➡ TLS has overhead in computation and transfers. But definitely worth it. ➡ Google likes it. ➡ Some cipher suites are better, but slower. ➡ Speed / Security compromise ➡ (try: “openssl speed”) 45

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https://tools.ietf.org/html/rfc7457 46 Summarizing Known Attacks on Transport Layer Security (TLS) and Datagram TLS (DTLS)

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TLS 1.3 47

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48 ➡ Still in draft ➡ 1-RTT (initial 0-RTT) for handshakes ➡ Dropped insecure features

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49 https://www.ssllabs.com/projects/best-practices/index.html

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http://farm1.static.ﬂickr.com/73/163450213_18478d3aa6_d.jpg 50

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51 Find me on twitter: @jaytaph Find me for development and training: www.noxlogic.nl Find me on email: jthijssen@noxlogic.nl Find me for blogs: www.adayinthelifeof.nl