ECB Mode of Operation

Threats on ECB Operational Mode

• If the message contain two identical blocks, the corresponding cipher blocks are also identical.
  • Eavesdropper gets some information.
• Consider data base rows being sent from one end to another
  • Columns: Name, Position, Salary
  • Each is 64 byte wide (block size: 64 bytes)
• Now the eavesdropper can find out
  • Number of people at a particular position
  • Number of people at the same salary.

Threats on ECB

• An employee can even alter the message to change his own salary.
• Serious flaws:
  • Some one looking at the cipher text can gain information from the repeated blocks.
  • Some can even alter or rearrange the cipher text to his advantage.
• ECB is rarely used to encrypt messages.