Exact model

Guess a random 128-bit AES key

Probability:
2.94 × 10⁻³⁷%
Odds:
1 to (3.4 × 10³⁸)
dBan
−385.3 dBan

A single blind guess has a vanishingly small chance of landing on the exact 128-bit key protecting encrypted data.

Calculation

p = 1 / 2¹²⁸ = 1 / 340,282,366,920,938,463,463,374,607,431,768,211,456

Assumptions

The AES key is generated uniformly, and the probability covers one independent key guess. Practical data protection also depends on software and key handling.

Sources

  1. NIST FIPS 197: Advanced Encryption Standard updated 9 May 2023