> This means that the same string can have a near-infinite number of entropy values? Yes. Entropy is a subjective measure (like confidence) rather than objecti

> This means that the same string can have a near-infinite number of entropy values? Yes. Entropy is a subjective measure (like confidence) rather than objective one (like length). Entropy measures an agent's uncertainty about the value of a variable. The entropy of the word "password" would be different for an English speaker and a non-English speaker. Your question of which password is more secure depends entirely on someone's method of guessing passwords. If someone just tries all single-digit passwords, then all 2-digit passwords, etc, then your passwords would be roughly equally secure. But if they use some other method that guesses more likely passwords first - checking against a database of pre-existing passwords, or first checking passwords with lower Kolmogorov complexity - then your '20a' password would be much less secure. By ordering passwords according to "likelihood", the second approach is essentially also ordering them with respect to entropy.