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NIST SP 800-63B Rev 4: SMS OTP is Now a Restricted Authenticator, But We Have the Fix

calendar_today August 15, 2025 person Raul Popa domain typingdna

Update, February 4th 2026: TypingDNA SMS+ just released publicly. Check it out! NIST’s updated Digital Identity Guidelines (SP 800-63B-4) formally classify SMS/PSTN one-time passcodes as a restricted authenticator.

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