totp-rs is a Rust library that permits the creation of 2FA authentification tokens per time-based one-time password (TOTP). Prior to version 1.1.0, token comparison was not constant time, and could theorically be used to guess value of an TOTP token, and thus reuse it in the same time window. The attacker would have to know the password beforehand nonetheless. Starting with patched version 1.1.0, the library uses constant-time comparison. There are currently no known workarounds.

Observable Timing Discrepancy in totp-rs