100x100 SQRL Logo   Secure Quick Reliable Login
A highly secure, comprehensive, easy-to-use replacement
for usernames, passwords, reminders, one-time-code
authenticators . . . and everything else.
Examining attacks against the SQRL system
This page examines the design of SQRL from the standpoint of its susceptibility and resistance to any form of attack by adversaries having any degree of access and knowledge of the system and user-specific secrets. We divide attacks into online information-based attacks, offline device attacks, and hybrid online/offline attacks.

Attack resistance assumptions
The SQRL system's public key based cryptographic design provides its operational network security with strong resistance to attacks upon the user's secret private key, and cryptographic signatures using that key. It is believed that the system's “25519” elliptic curve cryptography provides no less than the equivalent of a 2140 key strength. And while we believe that this renders the system extremely robust against attack, we'll note that the system's inherent use of per-site public key pairs means that even if it were possible to breach a user's security for one site, no information would be gained about the user's identity master key, nor about the keys used for identification and authentication on any other website.

The system's cryptographic design therefore appears to be extremely strong and highly resistant to fundamental breaches.

Network environment assumptions
< to be written >
• Examine SQRL login-page security requirements and implications.
• Examine smartphone authentication link security requirements and implications.

Password guessing
As discussed on previous pages, the only known area where explicit attack resistance must be added is in the protection against offline brute-force password guessing attacks. Online password guessing will be quickly foreclosed by a local password lockout and identity master key erasure. Since user passwords are used in two places, we'll examine each in turn:

Passwords for user-interface access
< to be written >

Passwords for external master key access
< to be written >

Lost Phone “Attack”
< to be written >
• Okay... not really an attack, but we need to address the consequences.

Evil App Attack
< to be written >
• It's clear how much damage could be done by any SQRL app that chose to betray its users.

Evil website attack
< to be written >

(Taylor Hornby of defuse.ca foresaw this attack. Thanks Taylor!)

Remote online attacks
< to be written >
• Note: DNS spoofing / MITM

Hybrid online/offline attacks
< to be written >

Botnet account creation attack
< to be written >
• Note: Proof-Of-Work

“Shoulder Surfing” effects
< to be written >
• What happens if someone snaps the SQRL code over one's shoulder?

Secure QR Login (SQRL) Documentation:

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Last Edit: Aug 02, 2015 at 14:17 (696.06 days ago)Viewed 7 times per day