How DES Was Cracked
Revisit the EFF DES Cracker (1998) and understand why 56-bit keys are fundamentally insufficient.
The 56-Bit Key Space
DES has 2^56 possible keys, which equals approximately 72 quadrillion (72,057,594,037,927,936) keys. While this sounds enormous, it is a finite space that can be systematically searched with enough computing power.
Key exhaustion (brute force) requires, on average, testing half the key space before finding the correct key. For DES, this means about 2^55 trial decryptions, each taking a few operations on modern hardware.
DES Challenge I (1997)
In 1997, RSA Data Security offered a $10,000 prize for breaking a DES-encrypted message. Rocke Verser coordinated a distributed computing effort across tens of thousands of internet-connected computers.
After 96 days of searching, the key was found. The plaintext was "Strong cryptography makes the world a safer place." The effort demonstrated that DES could be broken, though it required months and massive coordination.