In this section, we will turn to some purely mathematical reasoning to judge password strength. We will use tools from scikit-learn to learn and understand password strength by comparing them to past passwords using vector similarities.
Cosine similarity is a quantitative measure [-1,1] of how similar two vectors are in a Vector Space. The closer they are to each other, the smaller the angle between them. The smaller the angle between them, the larger the cosine of that angle is; for example:
- If two vectors are opposites of each other, their angle is 180, and cos(0) = -1.
- If two vectors are the same, their angle is 0, and cos(0) = 1.
- If two vectors are perpendicular, their angle is 90, ...
