2. WHY BOTHER?
Using SSL/TLS correctly is o en hard to achieve
...and understand!
Crucial for secure connection between systems
Globally deployed (intra-)cloud applications
9. Math time!
p = 11, q = 17 // two prime numbers
modulus = 187 // p * q
e = 3 // random number between 1 and modulus
// find d, so that (d * e) - 1 % (p - 1) * (q - 1) is zero
320 % 160 = 0
(321 - 1) % (10 * 16) = 0
(107 * 3) = 321 → d = 107
Note that d varies with e:
e = 7
// find d, so that (d * e) - 1 % (p - 1) * (q - 1) is zero
1280 % 160 = 0
(1281 - 1) % (10 * 16) = 0
(183 * 7) = 1281 → d = 183
10. Now, what if and are unknown?p q
p = 13 // prime number
q = 23 // prime number
modulus = 299 // p * q
e = 5 // random number between 1 and modulus
// find d, so that (d * e) - 1 % (p - 1) * (q - 1) is zero
1584 % 264 == 0
(1585 - 1) % (12 * 22) = 0
(317 * 5) = 1585 → d = 317
Turns out this is pretty hard!
11. For big enough and , finding those factors will cost an
eternity!
p q
So we can distribute ( p * q ) and even e!
12. d = 107
LET'S ENCRYPT THE LETTER 'G'
G → 7
7e → 73 → 343
343 % 187 → 156
LET'S DECRYPT THE MESSAGE '156'
156107 → 4.6 * 10234
156107 % 187 → 7
7 → G
18. But wait... anyone could create a certificate!
So we also need
Signature
Algorithm
Signature
Issuer
... and a way to sign stuff
19.
20. A is a mathematical relationship between a
message , a private key and a public key .
signature
x sk pk
It consists of two functions:
1. signing function
2. verifying function
t = f (sk, x)
[accept, reject] = g(pk, t, x)
So, given x and t and knowing pk,
we can tell if x is indeed signed by sk.
22. An entity that issues digital certificates, certifying the
ownership of a public key by the subject of the certificate.
23. "I can trust you, because I trust John, and John trusts Alice,
and Alice trusts you"
I
John
?
Alice
Who knows who "John" is?
Many "John"'s in todays browsers and operating systems!
25. FAIRYTALE TIME!
Once upon a time, a Dutch certificate
authority named DigiNotar was living
happily and carefree in the town of
Beverwijk.
But on a bad day, evil hurt it...
Real hard.
26. An attacker compromised a webserver of
DigiNotar due to a vulnerability that is
present within the DotNetNuke so ware.
DotNetNuke version 4.8.2.0 is installed on
host winsrv119. This version is affected by a
file upload vulnerability.
27. Due to the weak security of Windows
passwords it must be assumed that the
attacker was able to compromise the
passwords [...] of the accounts found on the
system. On the system, [...] the domain
administrator account [...] is present.
28. The attacker was able to traverse the
infrastructure and obtain access to at least
two CA's that were used to generate
certificates.
30. Google blacklists 247 certificates in Chromium
Microso 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 (except these are
self-signed)
33. Denotes where a can be found: a file that contains
.
is the password to that file.
JVM SETTINGS (1)
-Djavax.net.ssl.trustStore=<file>
truststore
trusted certs
-Djavax.net.ssl.trustStorePassword=...
34. Denotes where a can be found: a file that contains
.
is the password to that file.
JVM SETTINGS (2)
-Djavax.net.ssl.keyStore=<file>
keystore
private keys
-Djavax.net.ssl.keyStorePassword=...
35. Include debug logging for TLS handshake and connections.
JVM SETTINGS (3)
-Djavax.net.debug=all
