TEMPEST and Side Channel Attacks (5 of 5)

Differential Power Analysis

Differential Power Analysis takes multiple traces of two sets of data, and then computes the difference of the average of these traces.

If the difference is close to zero, then the two sets are not correlated, and if the power-value (typically ≥ 0.05) is higher, correlation can be assumed to be possible. By leveraging faster hardware and common sense, the difficult-to-solve 128-bit AES key can be broken into 16 bytes, where each byte can be solved individually.

Testing each byte requires only 28, or 256 attempts, which means it would only take 16 x 256 or 4,096 attempts to be able to decipher the entire encryption key. This is another attack that was once the preserve of state-backed intelligence operations.