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How do DNSCrypt, DoH, and DoT compare in resisting on-path attackers and DNS spoofing attacks?
Executive summary
Encrypted stub-to-resolver DNS protocols—DNSCrypt, DNS-over-TLS (DoT), and DNS-over-HTTPS (DoH)—all prevent casual on-path eavesdropping and many forms of on-path spoofing by encrypting and authenticating the channel between client and recursive resolver [1] [2]. They differ mainly in standardization, deployment model, and how hard they are for an on-path attacker or censor to block: DoH and DoT are IETF-standardized and widely deployed, DoH can blend into regular HTTPS traffic on port 443 making active blocking harder, and DNSCrypt predates those standards and focuses on channel authentication but is less standardized and less widely supported [3] [1] [4].
1. How encryption and authentication stop on-path attackers
All three remove the plaintext DNS query from an eavesdropper or local network attacker by encrypting the stub-to-resolver link; that prevents passive observation of the queries and prevents simple packet injection spoofing of responses on that link [1] [2]. DNSCrypt explicitly authenticates the channel and signs queries between client and resolver so a man-in-the-middle cannot easily inject or tamper with responses without the cryptographic keys [2]. DoT and DoH both rely on TLS to secure and authenticate the transport, providing the same practical protection against in-path tampering on the stub-to-recursive hop [1] [3].
2. Differences that matter to an on-path attacker or censor
DoH’s use of HTTPS over TCP port 443 lets DNS traffic blend with ordinary web traffic, making it more difficult for an on-path censor or middlebox to identify and block without disrupting general HTTPS [3]. DoT uses a dedicated port [5], which makes it simpler for network operators or censors to detect and block DoT specifically [1] [3]. DNSCrypt typically uses custom ports and an independent protocol design; that can make it harder to identify in some deployments but also means it lacks the broad, standardized transport advantages of TLS [4] [2].
3. Standardization, deployment and operational implications
DoH and DoT are IETF-standardized and have broader, mainstream implementations (browsers, OS support, public resolvers), which increases interoperability and consistent security properties; DNSCrypt, while mature and focused on channel authentication, has not been standardized through an IETF RFC and is therefore less uniformly implemented and less popular in mainstream stacks [1] [3] [4]. The practical consequence: attackers face a consistently secured TLS channel for DoH/DoT across many clients and resolvers, whereas DNSCrypt protection depends on the specific client/resolver implementation chosen [1] [2].
4. Limitations: what these protocols do not solve
None of these stub-to-resolver encryption methods extend to the entire DNS resolution path: queries that the recursive resolver issues to authoritative servers (the recursive→authoritative leg) remain in cleartext unless additional protections like DNSSEC or DANE are used—so on-path attackers between the recursive and authoritative servers are outside the protection these protocols provide [1]. DNSSEC is designed to authenticate DNS records themselves and complements encrypted transports by enabling clients or resolvers to detect forged records; that distinction is important because channel encryption alone does not cryptographically validate the DNS records [1] [2].
5. Practical resistance to DNS spoofing and which to pick
For preventing on-path spoofing at the stub link, all three offer effective protection: DNSCrypt authenticates the channel, DoT and DoH inherit TLS authentication—so in practice they “offer the same practical security level” for the stub-to-resolver hop according to comparison guidance [4] [1] [2]. If your priority is hiding DNS from a censor or making blocking expensive, DoH’s ability to intermingle DNS with HTTPS on port 443 is an operational advantage [3]. If you prefer a distinct channel and simpler firewall policies, DoT’s dedicated port is straightforward to manage [1]. If you prefer a protocol focused on channel authentication and are willing to manage nonstandard tooling, DNSCrypt remains an option though it’s less standardized [2] [4].
6. Conflicting views and caveats to consider
Some vendors and communities argue DNSCrypt gives the best privacy in theory because it authenticates queries at the channel level and predates the IETF efforts, but multiple sources caution that lack of standardization causes uneven implementations compared with DoH/DoT [2] [1] [4]. Conversely, advocates of DoT recommend it for system-wide protection outside browser contexts while DoH proponents highlight browser integration and blocking resistance—both positions are supported in current documentation [1] [3]. Available sources do not mention definitive head-to-head performance benchmarks or exhaustive security audits across all popular resolvers; those details are not found in current reporting.
Bottom line: for resisting local on-path attackers and simple DNS spoofing at the client↔resolver hop, any of DNSCrypt, DoT or DoH provides cryptographic protection; choose based on your operational needs—DoH for blending and censorship resistance (port 443), DoT for a dedicated encrypted channel (port 853), DNSCrypt if you want its specific channel-authentication model and can manage nonstandard deployment [3] [1] [2] [4].