--- title: How to Implement Two-Factor Authentication in ASP.NET Core description: A practical guide to implementing TOTP-based Two-Factor Authentication in ASP.NET Core. Covers how TOTP works, generating cryptographically secure secret keys... canonical: https://daily.dev/posts/how-to-implement-two-factor-authentication-in-asp-net-core-eyblhgeui twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: How to Implement Two-Factor Authentication in ASP.NET Core | daily.dev og:description: A practical guide to implementing TOTP-based Two-Factor Authentication in ASP.NET Core. Covers how TOTP works, generating cryptographically secure secret keys... og:url: https://daily.dev/posts/how-to-implement-two-factor-authentication-in-asp-net-core-eyblhgeui og:image: https://api.daily.dev/og/posts/eYblHGEUI.png og:image:alt: How to Implement Two-Factor Authentication in ASP.NET Core og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # How to Implement Two-Factor Authentication in ASP.NET Core **[Milan Jovanović](https://daily.dev/sources/milanjovanovic)** · 13 min read · 13 upvotes · 0 comments ## Summary A practical guide to implementing TOTP-based Two-Factor Authentication in ASP.NET Core. Covers how TOTP works, generating cryptographically secure secret keys with Otp.NET, creating QR codes using QRCoder, the correct two-step setup flow (pending → confirmed), issuing limited-scope tokens during login, validating codes with replay attack prevention via time-step tracking, rate limiting the validation endpoint, encrypting TOTP secrets at rest using AES with a key vault, and generating hashed one-time recovery codes. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: --- Tags: [#authentication](https://daily.dev/tags/authentication), [#c#](https://daily.dev/tags/c#), [#aspnetcore](https://daily.dev/tags/aspnetcore) [View this post on daily.dev](https://daily.dev/posts/how-to-implement-two-factor-authentication-in-asp-net-core-eyblhgeui) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"How to Implement Two-Factor Authentication in ASP.NET Core","url":"https://daily.dev/posts/how-to-implement-two-factor-authentication-in-asp-net-core-eyblhgeui","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/how-to-implement-two-factor-authentication-in-asp-net-core-eyblhgeui"},"datePublished":"2026-02-27T23:33:37.185Z","dateModified":"2026-02-27T23:33:59.246Z","description":"A practical guide to implementing TOTP-based Two-Factor Authentication in ASP.NET Core. 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