Information Security
 1. Introduction
  ○ Security by obscurity
   § Steganography
    □ Hiding data inside another form of data, like using non-used bits in image to hide a message
     § Cool, but not practical.
     § Disadvantages
      ◊ Algorithm secrecy vs. key secrecy
  ○ Cryptography is everywhere and yet if done right, you can barely see it.
  ○ Goals: 
   § Confidentiality
    □ Secrets stay secret.
   § Integrity
    □ Data is not tampered with.
   § Non-Repudiation
    □ No party can deny sending messages.
   § Authentication
    □ Each party can ensure that the sender is what they expect.
  ○ Cryptography
   § Hashing
   § Encryption
   § Signing
   § Protocols
  ○ Random Number Generators
   § Extremely important, almost all encryption/hashing strength is affected by how random the random number generator is.
   § Don't use simple random number, use a cryptographic random number generator with a sophisticated source of entropy.
   § Pseudorandom number generator
   § Dual_EC_DRBG random generator backdoor
 2. Body
  ○ Hashing (one Way)
   § Properties
    □ Fixed length output no matter what size the input was
    □ Very easy to compute the hash of a given message, however very hard to compute from a hash the corresponding input.
    □ Mathematically infeasible to generate a message that has a given hash
    □ Any modification to a message produces a completely different hash that has no relationship to the original message's hash.
    □ It is mathematically infeasible to find two messages with the same hash. Hash Collision
   § Hashing Functions
    □ Provides data integrity, however lacks authentication
    □ Examples
     ® MD5 
      ◊ Considered Insecure
     ® Secure Hash Family SHA-X, Sha-1, Sha-2 [Sha256, Sha512], Sha-3
      ◊ Sha-1 is considered insecure.
      ◊ Sha-1, Sha-2 designed by NSA
      ◊ Sha-3 is not designed by NSA, Competition winner.
    □ Attacks
     ® Brute force
      ◊ CPU's are getting faster and cheaper every day.
      ◊ GPU's are getting faster and cheaper every day.
      ◊ Special Hash calculating hardware is becoming more available especially with the BitCoin push.
     ® Rainbow table attacks
      ◊ Pre-Calculated tables where you can reverse lookup a hash to a value
      ◊ Try www.crackstation.net
   § Hash Message Authentication Codes (HMAC)
    □ Adds authentication to integrity
    □ Can be used with all previous algorithms, HMACMD5, HMACShA1, HMAC256 … etc.
   § Salted Hash
    □ Adds random salt to mitigate rainbow table
    □ Salts are unique per record, and not a secret.
   § Password Based Key Derivation Function (PBKDF2)
    □ RSA Public Key Cryptographic Standard PKCS #5 Version 2.0
    □ Internet Engineering Task Force RFC 2898 Specification
     ® Adds a lot of iterations to slow it just enough to mitigate brute force (default 50,000 iterations)
     ® Adds random salt to mitigate rainbow table
    □ Disadvantage: It can be easily implemented with hardware which makes it vulnerable to bruteforce even with high number of iterations
   § Bcrypt
    □ Password Hashing function
    □ State of the art password hashing
   § Usages
    □ Integrity Check
Password Storage

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EP46 - AskDeveloper Podcast - Cryptography - Part 1 - Introduction and Hashing

Weekly Podcast discussing the Egyptian IT industry, and various other technology related topics 
راديو عربي على الانترنت من المبرمجين المصريين للمبرمجين, باللغة العربية و باللهجة المصرية