Strong passwords

With a strength meter

No database: AIMRAN doesn't store your files, text or results

What is Strong passwords?

This tool creates passwords that are hard to guess. You can choose a random password with letters, numbers and symbols, or a passphrase made of Spanish words, which is easier to remember.

It also includes a checker: type a password and you'll see whether it's weak or strong and how long an attacker would take to crack it by trying combinations.

How to use it

  1. Choose the type: “Random” or “Passphrase”.
  2. Set the length (4 to 128 characters) or the number of words (3 to 12).
  3. Tick uppercase, lowercase, numbers and symbols, or choose the separator and passphrase options.
  4. Copy the password or generate several at once.
  5. To review one of yours, type it into “Check a password”.

Advantages

Technical details

Characters are chosen with crypto.getRandomValues and rejection sampling to avoid modulo bias; at least one character from each selected group is guaranteed and the result is shuffled with Fisher–Yates. The entropy of a random password is length × log2(alphabet size); for example, 20 characters using all four groups exceed 125 bits. The exclude-ambiguous option removes I, l, 1, O, 0 and similar symbols. Passphrases use a list of about 900 common Spanish words without accents or ñ (about 9.8 bits per word), with optional separator, capitalized first letter and number. The checker estimates entropy from the character types present and penalizes repetitions and sequences such as 1234 or qwer; the cracking time assumes 10 billion guesses per second against a fast hash. Levels: very weak < 40 bits, weak < 60, fair < 80, strong < 110 and very strong from 110.

Frequently asked questions

How many characters should a strong password have?

At least 12 to 16 characters mixing uppercase, lowercase, numbers and symbols. For important accounts, 20 or more, stored in a password manager.

What is a passphrase?

A password made of several random words, such as “faro-cereza-volcan-tigre”. With 5 or 6 words it's very secure and easier to remember than a string of symbols.

How long would it take to crack my password?

Type it into “Check a password” and you'll see an estimate assuming an attack of 10 billion guesses per second. It's a rough guide.

What's the point of excluding ambiguous characters?

It removes characters that are easily confused when reading, such as I, l, 1, O and 0, useful if you'll read the password out or copy it by hand.

Should I use the same password on several websites?

No. If one site suffers a data breach, all your accounts would be exposed. Use a different password for each service.

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