SSL/TLS for Mortals (Devoxx)

T L S
Awesome Sauce, or...
Maarten Mulders (@mthmulders)#tlsformortals

H
Exception in thread "main" javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed:
at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949)
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296)
at sun.security.ssl.ClientHandshaker.serverCertif cate(ClientHandshaker.java:1506)
at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216)
at sun.security.ssl.Handshaker.processLoop(Handshaker.java:979)
at sun.security.ssl.Handshaker.process_record(Handshaker.java:914)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387)
at sun.net. .protocol.https.HttpsClient.afterConnect(HttpsClient.java:559)
at sun.net. .protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
at sun.net. .protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1512)
at sun.net. .protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1440)
at sun.net. .protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
at it.mulders.maarten.Demo.main(Demo.java:13)
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderExc
at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:387)
at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)
at sun.security.validator.Validator.validate(Validator.java:260)
at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)
at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229)
at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
at sun.security.ssl.ClientHandshaker.serverCertif cate(ClientHandshaker.java:1488)
13 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to f nd valid certif cation path to requested target
at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:146)
at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:131)
at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:382)

7 L OSI M
data unit layers
Data
Data
Data
Segments
Packets
Application
Network Process to Application
Presentation
Data Representation
and Encryption
Session
Interhost Communication
Transport
EndtoEnd Connections
and Reliability
Network
Path Determination and
Host Layers

H SSL TLS
SSL 1.0 never released
SSL 2.0 1995 - 2011 (POODLE)
SSL 3.0 1996 - 2014 (POODLE)
TLS 1.0 1999 - 2011 (BEAST)
TLS 1.1 2006
TLS 1.2 2008
TLS 1.3 2018

D
What's the issue?!

H
1. public/private key encryption
2. signed certiﬁcates
3. certiﬁcate authorities

1 P P
K E

M
1. Select two prime numbers:
2. Calculate product:
3. Select random number < product:
4. Find d, so that
a.
b.
c.
d.
p = 11, q = 17
p ∗ q = 187
e = 3
(d ∗ e) − 1 mod (p − 1) ∗ (q − 1) = 0
(d ∗ 3) − 1 mod (10 ∗ 16) = 0
320 mod 160 = 0
(321 − 1) mod 160 = 0
(107 ∗ 3) = 321 ⇒ d = 107

N , P Q
1.
2. Find d, so that
Pretty hard without knowing and !
As soon as we know , calculating is trivial
(again).
p ∗ q = 299, e = 5
(d ∗ e) − 1 mod (p − 1) ∗ (q − 1) = 0
p q
p = 13, q = 23 d = 317

For big enough and , ﬁnding those factors will cost an
eternity!
So we can distribute and even !
p q
p ∗ q e

L "G"
p ∗ q = 187, e = 3, G ⇒ 7
= = 3437
e
7
3
343 mod 187 = 156

L "156"
Since we know and , we can calculatep q d = 107
= ≈ 4.6 ∗156
d
156
107
10
234
mod 187 = 7156
107
7 ⇒ G

N
Client Server
1 ClientHello →
2 ← ServerHello
3 ← Certiﬁcate
4 ← ServerKeyExchange
5 ← ServerHelloDone
6 ClientKeyExchange →
7 ChangeCipherSpec →
8 Finished →
9 ← ChangeCipherSpec
10 ← Finished

D
No-one is eavesdropping!

2 S
C

A certiﬁcate contains:
Serial Number
Subject
Validity
Usage
Public Key
Fingerprint Algorithm
Fingerprint

But wait... anyone could create a certiﬁcate!
So we also need
Signature Algorithm
Signature
Issuer
... and a way to sign certiﬁcates.

A signature is a mathematical relationship between a message
, a private key and a public key .
It consists of two functions:
1. signing function
2. verifying function
So, given and and knowing , we can tell if is indeed signed
by .
x sk pk
t = f (sk, x)
[accept, reject] = g(pk, t, x)
x t pk x
sk

3 C
A

An entity that issues digital certiﬁcates,
certifying the ownership of a public key
by the subject of the certiﬁcate.

I
John
?
Alice
So, who is John, anyway?
Many John's in todays browsers and operating systems!
“I can trust you, because I trust John, and
John trusts Alice, and Alice trusts you.

Top-notch security procedures, including "key ceremonies"

/** intentionally left blank */

W
Google blacklists 247 certificates in Chromium
Microsoft removes the DigiNotar root certificate from all
supported Windows-releases *
Mozilla revokes trust in the DigiNotar root certificate in all
supported versions
Apple issued Security Update 2011-005
Update Certificate Revocation Lists (although these are self-Maarten Mulders (@mthmulders)#tlsformortals

D
Trust (for what it's worth)

T , T T

Simple HTTP client with TLS support:
curl v k <address>
Troubleshoot trust issues and see certiﬁcates being used:
openssl s_client showcerts servername <address>
connect <address>:443
Troubleshoot supported protocols, ciphers, ...:
nmap script sslenumciphers p 443 <address>

JVM S
Djavax.net.ssl.trustStore=<file>
Denotes where a truststore can be found: a ﬁle that contains
trusted certs.
Djavax.net.ssl.trustStorePassword=changeit
is the password to that ﬁle.

JVM S
Djavax.net.ssl.keyStore=<file>
Denotes where a keystore can be found: a ﬁle that contains
public and/or private keys.
Djavax.net.ssl.keyStorePassword=changeit
is the password to that ﬁle.

JVM S
Djavax.net.debug=ssl[:flag]
Include debug logging for TLS handshake and connections.
Additional ﬂags:
record session sessioncache pluggability plaintext
handshake defaultctx keymanager data packet
keygen sslctx trustmanager verbose

P

P -
1. Don't use SSL!
Use TLS v1.2 or v1.3.
2. Be careful whom you trust!
3. When in doubt, open your toolbox:
openssl, curl, nmap and Portecle

Q
P D
I
Router by unknown author Maarten Mulders (@mthmulders)#tlsformortals

SSL/TLS for Mortals (Devoxx)

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