TOTP Visualizer
iTechVista TOTP Engine
Live Authenticator
HMAC-SHA1
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Time Drift Simulator (Education)
0s offset
Simulate a clock desync. Authenticator codes fail if your device time is incorrect.
Algorithm "X-Ray"
Real-time visualization of RFC 6238.
1. Time Counter (T)
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Unix Time (±drift) / 30 seconds.
2. HMAC-SHA1 Hash (Hex)
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20-byte hash from Secret Key + Time.
3. Dynamic Truncation
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Logic: Take the last byte's last nibble (0-15) as the Offset.
Extract 4 bytes starting at that offset (Orange).
Treat as 32-bit integer, mask sign bit, modulo 1,000,000.
Verify on Real Device
Scan this with Google Authenticator, Authy, or Aegis. The code should match exactly (if Drift is 0s).
Mini-Game: Crack the Code
Can you predict the next code without the key? Demonstrating High Entropy.