NIST Recommends Some Common-Sense Password Rules

NIST’s second draft of its “SP 800-63-4“—its digital identify guidelines—finally contains some really good rules about passwords:

The following requirements apply to passwords:

1. lVerifiers and CSPs SHALL require passwords to be a minimum of eight characters in length and SHOULD require passwords to be a minimum of 15 characters in length.
2. Verifiers and CSPs SHOULD permit a maximum password length of at least 64 characters.
3. Verifiers and CSPs SHOULD accept all printing ASCII [RFC20] characters and the space character in passwords.
4. Verifiers and CSPs SHOULD accept Unicode [ISO/ISC 10646] characters in passwords. Each Unicode code point SHALL be counted as a signgle character when evaluating password length.
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