[Extras/JFF] Implement OTP/TOTP Algorithm ground-up w/o external library

[TanmoySG]

[ JFF ] - Just For Fun Activity

Implement OTP/TOTP Algorithm ground-up without using any external libraries.

• Read/Research
• Implement
• Keep Notes
• Document

[TanmoySG]

[Refer]

• https://www.onelogin.com/learn/otp-totp-hotp
• https://www.geeksforgeeks.org/one-time-password-otp-algorithm-in-cryptography/

[TanmoySG]

[Refer]

• https://datatracker.ietf.org/doc/html/rfc6238
• https://datatracker.ietf.org/doc/html/rfc4226
• https://en.wikipedia.org/wiki/One-time_password