Passwords test values

pair 1 of 2 Two passwords that differ after byte 72

What it breaks

Step 1 of the 72-byte test: register a new account with this password of 73 bytes. Newer libraries such as Go x/crypto, Spring Security and bcrypt 5 for Python refuse it, and an application that does not catch that shows an error page already here.

What a correct application does

Registered, or refused with a message that names the length limit.

pair 2 of 2 Two passwords that differ after byte 72

What it breaks

Step 2: log in to the account from step 1 with this password, which differs only in its 73rd byte. A bcrypt hash that reads only the first 72 bytes, as in PHP, BCrypt.Net, jBCrypt, bcryptjs and pgcrypto, cannot tell the two apart.

What a correct application does

Login refused, because this is not the password the account was registered with.

pair 1 of 2 Two Polish passwords that differ after byte 72

What it breaks

Step 1 of the same test in Polish: 37 characters, under any limit counted in characters, and 73 bytes in UTF-8, because each l with stroke takes two bytes.

What a correct application does

Registered.

pair 2 of 2 Two Polish passwords that differ after byte 72

What it breaks

Step 2: log in with this password, which differs only in its last character. A limit of 64 or 72 characters does not stop a hash that reads 72 bytes from cutting it.

What a correct application does

Login refused.

pair 1 of 2 Password with and without a trailing space

What it breaks

Step 1 of the trimming test: register with a password that ends with a space. A layer that trims input stores the password without it.

What a correct application does

Registered, with the space kept as part of the password.

pair 2 of 2 Password with and without a trailing space

What it breaks

Step 2: log in with the password from step 1 without its last space, then once more with the space. Registration and login that trim differently let only one of the two in.

What a correct application does

Only the password with the space opens the account, or both do because both sides trim.

pair 1 of 2 Composed and decomposed forms of one password

What it breaks

Step 1 of the normalisation test: register with Polish letters written as single characters, the form a keyboard types.

What a correct application does

Registered.

pair 2 of 2 Composed and decomposed forms of one password

What it breaks

Step 2: log in with the same word written as base letters followed by combining accents. It looks identical, and hashing libraries take the bytes as given, so only an application that normalises the password lets it in.

What a correct application does

Login succeeds, because the password is normalised to NFC before it is hashed.

What it breaks

Passes a minimum length of 8, 12 or 15 characters and holds nothing a user could remember. A layer that trims input turns it into an empty password.

What a correct application does

Refused with the reason stated, or accepted and kept exactly, never trimmed to an empty password.

What it breaks

Four characters that String.length in JavaScript, .NET and Java counts as eight, because each takes two UTF-16 units, while Python, PostgreSQL and NIST SP 800-63B count four. A page and a server written in different languages disagree about the minimum length.

What a correct application does

Counted as four characters on the page and on the server, and accepted or refused the same way by both.

What it breaks

NIST SP 800-63B asks verifiers to accept at least 64 characters and the space, and a form with a maxlength of 20 or 32, or a rule against spaces, refuses the passphrase users are told to choose.

What a correct application does

Accepted in full, and the same passphrase opens the account afterwards.

What it breaks

Has an upper-case letter, a digit and a symbol, so it passes the usual composition rules, and appears more than 500,000 times in the Pwned Passwords list of breached passwords.

What a correct application does

Refused as a common or breached password, with the reason stated.

What it breaks

A keyboard pattern with a capital letter, digits and a symbol: it passes composition rules and appears more than 150,000 times in the Pwned Passwords list.

What a correct application does

Refused as a common or breached password, with the reason stated.

What it breaks

Registration accepts 100 characters while the login field has a lower maxlength, often 64, so the browser silently drops the rest and the user can never log in.

What a correct application does

The same password works on the registration, login and password change forms, or all three refuse it with the same limit stated.

What it breaks

NIST SP 800-63B asks verifiers to accept Unicode. A rule that allows only ASCII refuses it, or registration accepts it and an older layer in a single-byte encoding stores something else.

What a correct application does

Accepted, and the same password opens the account afterwards.

What it breaks

Request validation in ASP.NET on .NET Framework refuses a form value with a less-than sign followed by a letter, so a valid password ends at an error page.

What a correct application does

Accepted like any other printing ASCII character.

What it breaks

In a form-encoded body a plus means a space and %41 means A. A client that builds the body by hand without encoding sends Pa ssA-42, so the page and that client store different passwords.

What a correct application does

Stored and checked exactly as typed, through every client.