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CryptoParty

BSidesMSP 2014

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https://creativecommons.org/licenses/by-nc-sa/3.0/us/

https://creativecommons.org/licenses/by-nc-sa/3.0/us/legalcode

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Here Be Dragons

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CryptoProtocols

Use well supported libraries
Follow the documentation very carefully

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CryptoProtocols

Use well supported libraries
Follow the documentation very carefully
DO NOT WRITE YOUR OWN

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CryptoProtocols

Use well supported libraries
Follow the documentation very carefully
DO NOT WRITE YOUR OWN
… If you do write your own, then seek professional help

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CryptoProtocols

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CryptoProtocols

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Keys

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Key Types

Master Keys

Session Keys

Passwords/Passphrases

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Key Storage

Typed on a keyboard

Stored on disk

Stored in memory

Transmitted OOB

FOBs

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Key Management

Generate keys carefully and correctly
Are the keys stored online?
Who has access to the keys?
What are the consequences of losing the keys?
Are you sure?
Double check everything

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Random Number Generators

Truly Random

Pseudo Random

“...[generates] a sequence of numbers whose properties approximate the properties of sequences of random numbers.”

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What you want

Lots of entropy
Selectively Repeatable
Fast

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Implementations

random(3)

random(4) - /dev/random

random(4) - /dev/urandom

Yarrow

Dual_EC-DRBG

Hardware Sources

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Passwords/Passphrases

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Passwords/Passphrases

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Passwords/Passphrases

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Passwords/Passphrases

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What you want

Lots of entropy
Strong one way hashing
Always salted
Very slow

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Implementations

crypt(3)

scrypt

PBKDF2

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Shamir’s Secret Sharing

Split a secret into N parts

M parts are needed to recover the secret

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ssss

% ssss-split-passwd 4 2 'foobar'

Password to split (2 of 4): foobar

Split passwords:

1. splitPasswd = 3102f8123e3dac19

2. splitPasswd = 61fe89c40d18f6c0

3. splitPasswd = 92fa1b76dbe44176

4. splitPasswd = c3f6ad19aabf8c1d

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ssss

% ssss-join-passwd 61fe89c40d18f6c0 c3f6ad19aabf8c1d

Joined password : foobar

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Pretty Good Privacy

PGP/GPG

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Basics

Identities
Pair(s) of Public Keys
Signatures

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Identities

Fullname
Email Address
Comment
Picture

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Primary Keys

RSA/RSA
DSA/ElGamal

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Sub Keys

RSA or DSA or ElGamal
Specifically for Encrypting or Signing
Can be revoked without revoking the primary key

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PGP/GPG Key

% gpg -k 00D026C4

pub 2048D/00D026C4 2010-08-19 [expires: 2015-08-18]

uid [ unknown] GPGTools Team <team@gpgtools.org>

uid [ unknown] GPGMail Project Team (Official OpenPGP Key) <gpgmail-devel@lists.gpgmail.org>

uid [ unknown] GPGTools Project Team (Official OpenPGP Key) <gpgtools-org@lists.gpgtools.org>

uid [ unknown] [jpeg image of size 5871]

sub 2048g/DBCBE671 2010-08-19 [expires: 2015-08-18]

sub 4096R/0D9E43F5 2014-04-08 [expires: 2024-01-02]

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PGP/GPG Key

% gpg -k dokas@cs.umn.edu

pub 1024D/ECAB4C20 2000-05-03

uid [ultimate] Paul B. Dokas <dokas@mail.oitsec.umn.edu>

uid [ultimate] Paul B. Dokas <dokas@cs.umn.edu>

uid [ultimate] Paul B. Dokas <dokas@umn.edu>

uid [ultimate] Paul B. Dokas <dokas@oitsec.umn.edu>

sub 3072g/2A0DBC8B 2000-05-03

pub 1024R/E00F9AF9 1996-07-29 [revoked: 2000-05-03]

uid [ revoked] Paul B. Dokas <dokas@cs.umn.edu>

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PGP/GPG Key

% gpg -k paul@dokas.name

pub 4096R/7A2B4EFB 2011-03-22

uid [ultimate] Paul Dokas <dokas@dokas.name>

uid [ultimate] Paul Dokas <paul@dokas.name>

sub 4096R/EE20B803 2011-03-22

sub 2048R/F1B85DA1 2014-07-26

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Signatures

Sign a hash of the key
Transfers trust between keys

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PGP/GPG Signatures

% gpg --list-sig paul@dokas.name

pub 4096R/7A2B4EFB 2011-03-22

uid [ultimate] Paul Dokas <dokas@dokas.name>

sig 3 7A2B4EFB 2011-03-22 Paul Dokas <dokas@dokas.name>

sig ECAB4C20 2011-03-22 Paul B. Dokas <dokas@mail.oitsec.umn.edu>

sig C5854FEF 2011-03-30 Christopher R. Hertel (www.ubiqx.org - 2004 key) <crh@ubiqx.mn.org>

uid [ultimate] Paul Dokas <paul@dokas.name>

sig 3 7A2B4EFB 2011-03-22 Paul Dokas <dokas@dokas.name>

sig ECAB4C20 2011-03-22 Paul B. Dokas <dokas@mail.oitsec.umn.edu>

sig C5854FEF 2011-03-30 Christopher R. Hertel (www.ubiqx.org - 2004 key) <crh@ubiqx.mn.org>

sub 4096R/EE20B803 2011-03-22

sig 7A2B4EFB 2011-03-22 Paul Dokas <dokas@dokas.name>

sub 2048R/F1B85DA1 2014-07-26

sig 7A2B4EFB 2014-07-26 Paul Dokas <dokas@dokas.name>

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Quick Start

http://cryptnet.net/fdp/crypto/keysigning_party/en/keysigning_party.html

Chapter 4. Preparing For the Party

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Generating a Key

% gpg --gen-key

Please select what kind of key you want:

(1) RSA and RSA (default)

(2) DSA and Elgamal

(3) DSA (sign only)

(4) RSA (sign only)

Your selection? 1

RSA keys may be between 1024 and 8192 bits long.

What keysize do you want? (2048)

Requested keysize is 2048 bits

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Generating a Key

Please specify how long the key should be valid.

0 = key does not expire

<n> = key expires in n days

<n>w = key expires in n weeks

<n>m = key expires in n months

<n>y = key expires in n years

Key is valid for? (0) 2m

Key expires at Sun Sep 21 20:34:51 2014 CDT

Is this correct? (y/N) y

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Generating a Key

GnuPG needs to construct a user ID to identify your key.

Real name: Paul B. Dokas

Email address: testing@dokas.name

Comment: THIS IS ONLY FOR TESTING!

You selected this USER-ID:

"Paul B. Dokas (THIS IS ONLY FOR TESTING!) <testing@dokas.name>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o

You need a Passphrase to protect your secret key.

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Generating a Key

We need to generate a lot of random bytes. It is a good idea to perform

some other action (type on the keyboard, move the mouse, utilize the

disks) during the prime generation; this gives the random number

generator a better chance to gain enough entropy.

We need to generate a lot of random bytes. It is a good idea to perform

some other action (type on the keyboard, move the mouse, utilize the

disks) during the prime generation; this gives the random number

generator a better chance to gain enough entropy.

gpg: key 400DB485 marked as ultimately trusted

public and secret key created and signed.

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Generating a Key

gpg: checking the trustdb

gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model

gpg: depth: 0 valid: 2 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 2u

gpg: next trustdb check due at 2014-09-22

pub 2048R/400DB485 2014-07-24 [expires: 2014-09-22]

Key fingerprint = 6943 3DDA F70C E847 DF8D 49C2 4C21 9D82 400D B485

uid Paul B. Dokas (THIS IS ONLY FOR TESTING!) <testing@dokas.name>

sub 2048R/DD417008 2014-07-24 [expires: 2014-09-22]

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PGP/GPG Keys

DO NOT LOSE YOUR PRIVATE KEY!

DO NOT GIVE ANYONE ACCESS TO YOUR PRIVATE KEY!

DO NOT LOSE YOUR REVOCATION CERT!

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PGP/GPG Generation and Storage

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Generating a Revocation Cert

% gpg --output revoke.asc --gen-revoke 400DB485

sec 2048R/400DB485 2014-07-24 Paul B. Dokas (THIS IS ONLY FOR TESTING!) <testing@dokas.name>

Create a revocation certificate for this key? (y/N) y

Please select the reason for the revocation:

0 = No reason specified

1 = Key has been compromised

2 = Key is superseded

3 = Key is no longer used

Q = Cancel

(Probably you want to select 1 here)

Your decision? 0

Enter an optional description; end it with an empty line:

>

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Generating a Revocation Cert

Reason for revocation: No reason specified

(No description given)

Is this okay? (y/N) y

You need a passphrase to unlock the secret key for

user: "Paul B. Dokas (THIS IS ONLY FOR TESTING!) <testing@dokas.name>"

2048-bit RSA key, ID 400DB485, created 2014-07-24

ASCII armored output forced.

Revocation certificate created.

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Generating a Revocation Cert

Please move it to a medium which you can hide away; if Mallory gets

access to this certificate he can use it to make your key unusable.

It is smart to print this certificate and store it away, just in case

your media become unreadable. But have some caution: The print system of

your machine might store the data and make it available to others!

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Generating a Revocation Cert

-----BEGIN PGP PUBLIC KEY BLOCK-----

Version: GnuPG/MacGPG2 v2.0.22 (Darwin)

Comment: GPGTools - https://gpgtools.org

Comment: A revocation certificate should follow

iQEfBCABCgAJBQJT0GULAh0AAAoJEEwhnYJADbSFFpMIAJ6gWGtxyI9KteDiX8T3

h8lzVc/pEBG5Jotwu56oC00bOqDtkno0Arhe+cZMTwXqhIsYk6CMYEXrLlUpsByV

cbzKtkHkcvr9kpWF4v+pF3ze17Fdez/bFGj9JPGyP8B1/MlDkZq9cpMIQA6BSeeF

DgyBdD9tyJgwZp8hsWIgi0AKcLGOZgjX4Mo8a2aSQgiyK5AgTRzZ/5483irysrY0

NFIZcggDCBa1HdNORb6hAujnVGiRrK9pPISVzDqw1McroFlfHnEsPieP94ZHwm9d

BnVPfe4wOaL+7WTfkdRUO4PgTGiBCIkHH2Su32cMVLcjigfAkTrSYZEtErSCyoiK

KMo=

=Jfwe

-----END PGP PUBLIC KEY BLOCK-----

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Adding Sub Keys

% gpg --edit-key 400DB485

Secret key is available.

pub 2048R/400DB485 created: 2014-07-24 expires: 2014-09-22 usage: SC

trust: ultimate validity: ultimate

sub 2048R/DD417008 created: 2014-07-24 expires: 2014-09-22 usage: E

[ultimate] (1). Paul B. Dokas (THIS IS ONLY FOR TESTING!) <testing@dokas.name>

gpg> addkey

Key is protected.

You need a passphrase to unlock the secret key for

user: "Paul B. Dokas (THIS IS ONLY FOR TESTING!) <testing@dokas.name>"

2048-bit RSA key, ID 400DB485, created 2014-07-24

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Adding Sub Keys

Please select what kind of key you want:

(3) DSA (sign only)

(4) RSA (sign only)

(5) Elgamal (encrypt only)

(6) RSA (encrypt only)

Your selection? 3

DSA keys may be between 1024 and 3072 bits long.

What keysize do you want? (2048)

Requested keysize is 2048 bits

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Adding Sub Keys

Please specify how long the key should be valid.

0 = key does not expire

<n> = key expires in n days

<n>w = key expires in n weeks

<n>m = key expires in n months

<n>y = key expires in n years

Key is valid for? (0) 1w

Key expires at Wed Jul 30 20:54:41 2014 CDT

Is this correct? (y/N) y

Really create? (y/N) y

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Adding Sub Keys

We need to generate a lot of random bytes. It is a good idea to perform

some other action (type on the keyboard, move the mouse, utilize the

disks) during the prime generation; this gives the random number

generator a better chance to gain enough entropy.

gpg: WARNING: some OpenPGP programs can't handle a DSA key with this digest size

pub 2048R/400DB485 created: 2014-07-24 expires: 2014-09-22 usage: SC

trust: ultimate validity: ultimate

sub 2048R/DD417008 created: 2014-07-24 expires: 2014-09-22 usage: E

sub 2048D/6DFEDE5E created: 2014-07-24 expires: 2014-07-31 usage: S

[ultimate] (1). Paul B. Dokas (THIS IS ONLY FOR TESTING!) <testing@dokas.name>

gpg> save

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Sending Keys to Key Servers

% gpg --send-keys 400DB485

gpg: sending key 400DB485 to hkp server keys.gnupg.net

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Retrieving Keys from Key Servers

% gpg --recv-key 7A2B4EFB

gpg: requesting key 7A2B4EFB from hkp server keys.gnupg.net

gpg: key 7A2B4EFB: "Paul Dokas <dokas@dokas.name>" not changed

gpg: Total number processed: 1

gpg: unchanged: 1

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Updating Keys from Key Servers

% gpg --refresh-key

gpg: refreshing 40 keys from hkp://keys.gnupg.net

gpg: requesting key 00D026C4 from hkp server keys.gnupg.net

<snip, snip>

gpg: key 00D026C4: "GPGTools Team <team@gpgtools.org>" 353 new signatures

gpg: key 00D026C4: "GPGTools Team <team@gpgtools.org>" 1 new subkey

gpg: key 7A2B4EFB: "Paul Dokas <dokas@dokas.name>" not changed

gpgkeys: key 69433DDAF70CE847DF8D49C24C219D82400DB485 not found on keyserver

<snip, snip>

gpg: Total number processed: 39

gpg: unchanged: 38

gpg: new subkeys: 1

gpg: new signatures: 353

gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model

gpg: depth: 0 valid: 2 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 2u

gpg: next trustdb check due at 2014-09-22

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Key Fingerprints

% gpg --fingerprint 7A2B4EFB

pub 4096R/7A2B4EFB 2011-03-22

Key fingerprint = CD7F 7901 B462 4C36 4329 20D4 6F4D 5E6A 7A2B 4EFB

uid [ultimate] Paul Dokas <dokas@dokas.name>

uid [ultimate] Paul Dokas <paul@dokas.name>

sub 4096R/EE20B803 2011-03-22

sub 2048R/F1B85DA1 2014-07-26

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Signing Keys

gpg> sign

Really sign all user IDs? (y/N) y

pub 4096R/7A2B4EFB created: 2011-03-22 expires: never usage: SC

trust: unknown validity: unknown

Primary key fingerprint: CD7F 7901 B462 4C36 4329 20D4 6F4D 5E6A 7A2B 4EFB

Paul Dokas <dokas@dokas.name>

Paul Dokas <paul@dokas.name>

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Signing Keys

Are you sure that you want to sign this key with your

key "Paul Dokas <paul.dokas@code42.com>" (660496A0)

Really sign? (y/N) y

You need a passphrase to unlock the secret key for

user: "Paul Dokas <paul.dokas@code42.com>"

4096-bit RSA key, ID 660496A0, created 2013-09-13

gpg> save

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Revoking Key Signatures

gpg> revsig

You have signed these user IDs on key 7A2B4EFB:

Paul Dokas <dokas@dokas.name>