Using Cryptography Properly in

Applications

Andy WatsonIonic Security

#GWOCryptoParty

Great Wide Open2016

About:Name: Andy WatsonOccupation: Byte ManglerEmployer: Ionic Security

http://ionic.com/

Why am I here?I’ve seen too many people not using cryptography or using it incorrectly.

This information may help you not be one of them.

Agenda:● Random● Salt● Hash● Key Derivation● Symmetric Encryption● Famous Mistakes

Random

Random Number GeneratorsRNG: A computational or physical device designed to generate a sequence of numbers that lack any patternTrue random number generators depend on an entropy source like radioactive decay or radio frequency noise

For cryptographic functions, higher levels of entropy are required to work properlyhttps://www.random.org/randomness/

PseudoComputational RNG are known as Pseudo RNG

PRNG are “seeded” with a value to generate a series of numbers

Hashes

HASH!

Hashing Function (n.)A Function that represents data of arbitrary size as data of a fixed size.

$ echo "Great Wide Open 2016" | md5 e2be8adfadee4bfe635041c4c37dadac

$ echo "All Things Open 2015 " | md5402854038fbffe281a518b53cdbd5594

When to HashUse hashing functions when saving the original data would be a liability you have no business dealing with

For Example: Linux Passwords

$6$pWVzxN/iFRstrZ/.$TNBvzXhc8b9SBkl1q36YNvF2DwuS4/7LsICepYgaWCKzM1MS.OBK5TvxrUQ4.I5x5NtqidhBTGobQLOqxBAFe1

Don’t Store The ClearCredentials should be hashed when stored

During login, hash the password entered and check it against the hash you saved

When Hashes CollideThese two blocks have the same md5 hash of 79054025255fb1a26e4bc422aef54eb4

d131dd02c5e6eec4693d9a0698aff95c 2fcab58712467eab4004583eb8fb7f89 55ad340609f4b30283e488832571415a 085125e8f7cdc99fd91dbdf280373c5b d8823e3156348f5bae6dacd436c919c6 dd53e2b487da03fd02396306d248cda0 e99f33420f577ee8ce54b67080a80d1e c69821bcb6a8839396f9652b6ff72a70

d131dd02c5e6eec4693d9a0698aff95c 2fcab50712467eab4004583eb8fb7f8955ad340609f4b30283e4888325f1415a 085125e8f7cdc99fd91dbd7280373c5bd8823e3156348f5bae6dacd436c919c6 dd53e23487da03fd02396306d248cda0e99f33420f577ee8ce54b67080280d1e c69821bcb6a8839396f965ab6ff72a70

You. Must. Hash. Securely.Cryptographically Secure Hash Function (n.)A hash function which is infeasible to reverse back to the original message and not subject to collisions$ echo "Great Wide Open 2016" | shasum -a 51240094ad14fec6107ccabbc430e00cb9ef34f75a45420ca055eb294ccbcc8f2084da4ec10f852c4e6cc372d2f3f7ab34fbfc113661b2735243621509ef9b3d3dd

Taste the Rainbow TableA rainbow table is a precomputed table for reversing cryptographic hash functions, usually for cracking password hashes.

Password MD5 Hash123456e10adc3949ba59abbe56e057f20f883epassword5f4dcc3b5aa765d61d8327deb882cf99

It’s not just for your friesSALT

What is a Salt?Random data added to your input to create better output from one way functionsUseful for defending against dictionary and rainbow table attacks.$ echo "secret" | md5Dd02c7c2232759874e1c205587017bed$ openssl rand -hex 1672f72e199d1292317ee60cbe3c50b5ba$ echo "72f72e199d1292317ee60cbe3c50b5ba secret" | md57cb940bf5166c52834a9e831a6299091

Key Derivation

Key Derivation FunctionsKDF create new secret keys from a secret value and a known value - like a password

Key Derivation Functions can be used in a “key stretching” routing to enhance hashing functions to provide much more protection from rainbow tables and brute force attacks

Original KDF: crypt● Invented in 1978 to protect UNIX

passwords● Used only a 12 bit salt● Limited passwords to 8 characters

Modern KDFsPDKDF2● 64 bit random salt● 5000 iterations of SHA1 (hashing function)

SCRYPT● Consumes large amounts of memory

on purpose

PBKDF2 In A Nutshell™

Password

SALT + Password

Prepend SALT

Intermediate Hash

SHA1

REPEAT 5000 TIMES

Final Hash

Save the SaltStore the salt, the resulting hash and the number of iterations in your data store

You’ll have to calculate the derived key of the credential again to verify it is correct

https://crackstation.net/hashing-security.htm

Vulnerabilities• ASICs exists that can run PBKDF2

processes very quickly• bcrypt requires the use of more

memory so it makes it harder to implement in silicon

• scrypt is more modern and can be tuned to use even more memory

Symmetric Encryption

Symmetric EncryptionUsed when your application needs to protect data at rest (on disk etc) but will need to use those values later

The most common algorithm for symmetric encryption is AES (Advanced Encryption Standard)

It can operate in multiple modes like ECB, CBC, CTR and GCM - each suited to different uses

ECB ModeElectronic Code BookSimplest mode: Operates on blocks of plaintext

Comparing ECB to other modes

http://en.wikipedia.org/wiki/Block_cipher_mode_of_operation

Galois Counter Mode (GCM)Encrypts and Authenticates Messages

Reduces the opportunity for interference with messages to go undetected

Functions at a high rate of speed

Became NIST standard in 2007

Simple!

https://en.wikipedia.org/wiki/Galois/Counter_Mode

Uses of GCM• TLS 1.2• SSH• IPsec

Let’s talk about it.Mistakes Were Made

The Stupid. It Hurts.

Le Sigh.My password is stored in their database in plaintext.

It was not hashed or they could not have emailed it to me!

Obviously, the password I use with them is a special snowflake.

Which is bad because...A lot of people use the same password everywhere and use their email address as their login!

So...An attacker that gets this password list can try to log in to all kinds of things as you!

1. email2. banks3. credit reporting4. even NetFlix!

Adobe HackMillions of “encrypted” passwords stolenHashed with MD5Large numbers of them found in rainbow tables

Most Common Password: 123456http://stricture-group.com/files/adobe-top100.txt

Beware The Default SettingsDefault settings for Android Bouncy Castle starting in 2.1 were horribly unsafeDefaulted to ECB mode!

Empirical Study of Android Apps11,748 applications analyzed5,656 used ECB mode by default3,644 used a constant symmetric key2,000 used ECB mode ON PURPOSE!1,932 used a constant IV1,629 seeded PRNG with static value

Seeding the PRNGIn 2006 a bug in Debian and Ubuntu caused the PID to be used as the output of the PRNG - only 32,768 possible values!

(hint: that’s not enough!)

UnSalted HashesIn 2012, LinkedIn password hashes were stolen.

They were not salted.

60% of them were cracked.

Crisis Averted at SlackUser profile data stolen in February 2015

Passwords hashed with bcrypt and random salts

Unlocking Your PriusSystem uses rotating codes in a small rangeSome built in (pre-shared) keys for repair use

No protection from replaying codesBrute force attacks possible

Scared yet?

@andrewwatsonhttp://about.me/andrewwatson

Thank You