Useful Cryptography, An Introduction

Cryptography is often thought of as a scary topic, but it doesn't have to be. In this talk, you'll learn about different types of useful cryptography, how they work (without needing a PhD in mathematics), and how to immediately start applying these concepts in your projects.

Transcript

1. @rdegges @oktadev
   Useful Cryptography
   An Introduction
   

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2. @rdegges @oktadev
   Hey, I'm Randall
   Builder Python / JS /
   Go Hacker
   Author
   Open Source
   Chief Hacker @ Okta
   

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3. @rdegges @oktadev
   I am not a cryptographer!
   

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4. @rdegges @oktadev
   Why even?
   you website
   database
   website
   "how to store passwords"
   password hashing
   god
   

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5. @rdegges @oktadev
   I literally can't even.
   Developers should never
   do crypto.
   

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6. @rdegges @oktadev
   Hashing
   

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7. @rdegges @oktadev
   What is a Hash Function?
   hash(s)
   Input Hash (Digest)
   "ilovemymom" "6cd7c44ad701d00aa59b4225978e9c7ddf00c682"
   "ilovemymom" "6cd7c44ad701d00aa59b4225978e9c7ddf00c682"
   "wooooboyyyyyyyyy" "968360efa4e572ba34504af1d438b1fc60871943"
   deterministic
   unique
   irreversible
   

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8. @rdegges @oktadev
   Hahes are great for information that
   you need to verify but never persist.
   web server
   Email: r@rdegges.com
   Password: ilovemymom
   db
   Password:
   pwn3d!
   Password: ilovemymom
   I want to create an account.
   

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9. @rdegges @oktadev
   How User Login Works with Hashing
   web server
   Email: r@rdegges.com
   Password: ilovemymom
   db
   Email: r@rdegges.com
   I want to log into my account.
   Password:
   Compute hash("ilovemymom")
   Compare hash("ilovemymom") ==
   Equal? Login successful!
   Unequal? No login for you!
   

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10. @rdegges @oktadev
    There are two types of
    hashing algorithms.
    ??!?!
    Cryptographic hash
    functions
    Password hash
    functions
    Oh my!
    

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11. @rdegges @oktadev
    Cryptographic Hash Functions
    AKA: the fast ones
    ubuntu-18.04.2-desktop-amd64.iso
    (1.9 GB)
    $ sha1sum ubuntu-18.04.2-desktop-amd64.iso
    bcdb9099024c468047f3f31c7d23e68a35ea4de2
    (3.176 seconds)
    ubuntu
    ubuntu-18.04.2-desktop-amd64.iso
    Hash: bcdb9099024c468047f3f31c7d23e68a35ea4de2
    

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12. @rdegges @oktadev
    Cryptographic hash functions
    are useful for verifying the
    integrity of data.
    MD5 (1991) SHA-1 (1995)
    SHA-2 (2001)
    SHA-3 (2015) BLAKE 2 (2012)
    *Latacora (2018)
    *
    Ron Rivest
    RSA!
    

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13. @rdegges @oktadev
    Password Hash Functions
    AKA: the slow ones
    Password: "ilovemymom"
    db
    sha2("ilovemymom")
    sha2(pass)
    ??!?!
    Brute force!
    for pw in pw_generator():
    if sha2(pw) == stolen_hash:
    print 'Password found!'
    Dictionary lists
    Sequential
    Breached password databases
    

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14. @rdegges @oktadev
    

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15. @rdegges @oktadev
    Password hash functions are
    useful for storing sensitive
    password data and keys.
    PBKDF2 (2000)
    bcrypt (1999)
    scrypt (2009)
    argon2 (2015)
    argon2i
    argon2d
    argon2id
    hash(pass)
    hash( )
    

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16. @rdegges @oktadev
    

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17. @rdegges @oktadev
    Randomness
    API Keys
    Random Numbers
    Passphrases
    Database IDs
    

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18. @rdegges @oktadev
    There are two "kinds" of security.
    computational
    information-theoretic
    

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19. @rdegges @oktadev
    The best way to generate random
    numbers is /dev/urandom.
    OS kernel
    keyboard timings
    mouse movements
    storage timings
    random pool
    /dev/random
    /dev/urandom
    app
    OSX
    FreeBSD
    Linux
    NetBSD
    CSPRNG
    

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20. @rdegges @oktadev
    

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21. @rdegges @oktadev
    Encryption
    

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22. @rdegges @oktadev
    Encryption is useful for hiding data
    you need to eventually see again.
    app
    s3
    passwords.txt
    passwords.txt.enc
    shit :/
    ciphertext
    

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23. @rdegges @oktadev
    There are two types of encryption.
    symmetric
    asymmetric
    

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24. @rdegges @oktadev
    Symmetric Encryption
    data
    secret
    ciphertext secret
    data
    ciphertext
    Encryption Decryption
    Long, random string.
    

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25. @rdegges @oktadev
    Symmetric encryption is useful in
    circumstances where you can keep a
    trusted secret safe.
    web server
    AWS_ACCESS_KEY_ID
    AWS_SECRET_ACCESS_KEY
    SIGNING_KEY
    ENCRYPTION_KEY
    ...
    

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26. @rdegges @oktadev
    How should you do symmetric encryption?
    * Amazon KMS
    *Latacora (2018)
    AWS Encryption SDK
    KMS
    master key(s)
    data
    data key
    encryption
    algorithm ciphertext
    encryption
    algorithm
    encrypted data key
    encrypted
    message
    

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27. @rdegges @oktadev
    How should you do symmetric decryption?
    KMS
    master key(s)
    data
    data key
    decryption
    algorithm
    ciphertext
    encrypted data key
    encrypted
    message
    decryption
    algorithm
    

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28. @rdegges @oktadev
    It sounds complex, but...
    aws.encrypt(plaintext)
    aws.decrypt(encrypted message)
    

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29. @rdegges @oktadev
    Asymmetric encryption is useful in
    circumstances where you need to
    exchange data securely between
    untrusted parties.
    inbox
    email
    rdegges.com
    tls
    

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30. @rdegges @oktadev
    Asymmetric Encryption
    ciphertext
    data
    public
    key
    private
    key
    Bob Alice
    ciphertext
    data
    public
    key
    private
    key
    shareable
    

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31. @rdegges @oktadev
    How should you do asymmetric encryption?
    * NaCl/libsodium
    *Latacora (2018)
    Box API
    Bob Alice
    public
    key
    private
    key
    public
    key
    private
    key
    box(bs, ap)
    ciphertext
    data
    box.encrypt(data)
    

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32. @rdegges @oktadev
    How should you do asymmetric decryption?
    Bob Alice
    public
    key
    private
    key
    public
    key
    private
    key
    ciphertext
    data
    box(as, bp)
    box.decrypt(c)
    

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33. @rdegges @oktadev
    Don't roll your own crypto. Use crypto
    and be smart about it.
    

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34. @rdegges @oktadev
    

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35. @rdegges @oktadev
    Thank You
    rdegges.com
    developer.okta.com
    

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36. @rdegges @oktadev
    Sources
    ● "Cryptographic Right Answers":
    https://latacora.micro.blog/2018/04/03/cryptographic-right-answers.html
    ● "Password Hashing Competition": https://password-hashing.net/
    ● "Myths About /dev/urandom": https://www.2uo.de/myths-about-urandom/
    ● "When to use /dev/random vs /dev/urandom":
    https://unix.stackexchange.com/questions/324209/when-to-use-dev-random-vs-dev-urandom
    ● "djb" on /dev/urandom:
    https://www.mail-archive.com/cryptography@randombit.net/msg04763.html
    ● KMS FAQ: https://aws.amazon.com/kms/faqs/
    ● PyNaCl: https://pynacl.readthedocs.io/en/stable/public/
    

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