# Tag Info

A common method for constant-time comparison goes $r←0$ for each bit/byte/word $x_i$ and $y_i$ to compare $r←r ∨ (x_i⊕y_i)$   where $∨$ stands for bitwise OR and $⊕$ stands for bitwise XOR all the $x_i$ match the corresponding $y_i$ if and only if $r$ is now $0$ The point is that the duration is independent of the data compared, thus measuring ...