Social Engineering

Hashes

• Preimage attacks - given h(M), find M
• 2nd preimage attack - given M, find M’ where h(M) = h(M’)
• Collision resistant - find two messages M and M’ where h(M) = h(M’)
  

Uses of Hashes

• Fingerprinting
• Passwords
• Proof of Work
• Commitment
• MAC

Avalanche Property

A small change causes about 50% of the bits