HTTP Digest Authentication Against Algorithm Downgrade Attacks
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Solution Overview
Problem
Existing HTTP Digest Access Authentication is vulnerable to attacks where malicious proxies intercept and remove stronger digest algorithm headers, forcing clients to use weaker algorithms, leading to security insecurities in the negotiation process.
Innovation Solution
The proposed solution involves a client device and server device that perform digest access authentication by sending and receiving multiple challenges with different digest algorithms, calculating a response indicative of all algorithms, and verifying the correctness of the response to ensure secure negotiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the server sends multiple digest algorithm challenges, then the security of authentication is improved, but the complexity of the authentication process increases
Solution Approach 1:
The server performs preliminary action by pre-calculating and storing hash values for multiple digest algorithms (MD5, SHA-256, etc.) before the authentication process begins. When a challenge-response authentication is initiated, the server can immediately verify the client's response using any of the supported algorithms without performing additional computational overhead, thus maintaining high security while managing complexity efficiently.
Solution Approach 2:
The authentication system is designed with multi-functionality to support multiple digest algorithms (MD5, SHA-256, and others) within a single authentication framework. The server and client can negotiate and use any of the supported algorithms, making the system universal and adaptable to different security requirements without requiring separate authentication mechanisms for each algorithm.
2Adaptability or versatility
If the client calculates response using one algorithm while server verifies with multiple algorithms, then authentication flexibility is improved, but verification complexity increases
Solution Approach 1:
The server performs preliminary action by pre-computing and storing the expected hash values for multiple digest algorithms during the challenge phase. When verifying the client's response, the server simply compares the received hash against the pre-computed values for each algorithm, reducing verification complexity while maintaining the ability to support multiple algorithms flexibly.
Solution Approach 2:
The authentication mechanism incorporates feedback by allowing the client to indicate which algorithm was used in the response, and the server uses this feedback to select the appropriate verification method. This feedback loop enables efficient verification by avoiding unnecessary comparisons across all algorithms while maintaining adaptability.
3Ease of operation
If malicious proxy removes strong algorithm headers, then client uses weaker algorithm, but security is compromised
Solution Approach 1:
The client performs preliminary anti-action by incorporating a integrity check mechanism that verifies the authenticity of the challenge headers received from the server. The client can detect if strong algorithm headers have been removed or modified by a malicious proxy through cryptographic verification, and refuse to proceed with authentication if integrity is compromised, thus preventing downgrade attacks.
Solution Approach 2:
The patent introduces an intermediary verification mechanism that acts as a mediator between the client and server to ensure the integrity of the algorithm negotiation process. This intermediary layer (in the form of cryptographic verification) detects and prevents malicious interference, allowing the system to maintain security even in the presence of potential proxy attacks.
Data Source
AI summary
A method comprising a client device performing digest access authentication with a server device. The digest access authentication comprises sending a first request towards the server device for accessing a resource. The digest access authentication comprises receiving a first response from the server device. The first response comprises at least two challenges and indications of as many different digest algorithms, one digest algorithm is associated with each challenge. The digest access authentication comprises calculating a response to one of the challenges using the digest algorithm associated with said one of the challenges. The response to said one of the challenges is indicative of all of the different digest algorithms. The digest access authentication comprises sending a second request towards the server device for accessing the resource. The second request comprises the response to said one of the challenges. The digest access authentication comprises receiving a second response from the server device. The second response indicates successful digest access authentication with the server device.