HASSH SSH Fingerprinting for Client Authentication
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Solution Overview
Problem
Current SSH protocols lack a scalable framework to verify the authenticity of SSH components, making it difficult to distinguish between legitimate and malicious clients, as there is no reliable method to confirm the underlying algorithms used by SSH clients and servers.
Innovation Solution
Implementing a HASSH (Hash-Based SSH) mechanism that generates unique fingerprints for SSH clients and servers by performing a cryptographic hash on the set of supported algorithms, allowing for secure communication by verifying these fingerprints during the SSH negotiation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If SSH clients claim to be benign by specifying version information in text fields, then the SSH connection can be established easily, but the authenticity of the SSH client cannot be verified
Solution Approach 1:
The system performs preliminary actions by pre-computing and storing HASSH fingerprints for known legitimate SSH clients during a profiling phase. These fingerprints are derived from the clients' algorithm preferences and are stored in a database before actual SSH connections occur, enabling rapid verification without impacting connection establishment speed
Solution Approach 2:
The invention creates a cryptographic copy (HASSH fingerprint) of the SSH client's algorithm preference set. Instead of verifying the entire client identity, the system generates a compact hash representation that can be quickly compared against stored profiles, maintaining verification reliability while preserving ease of operation
2Reliability
If cryptographic hashing is performed on SSH algorithm sets to generate fingerprints, then SSH client authenticity can be verified, but additional computational overhead is introduced
Solution Approach 1:
The computationally intensive cryptographic hashing is performed in advance during the profiling phase, not during actual SSH connections. The HASSH fingerprints are pre-computed and stored, so during connection verification, the system only needs to perform a simple hash comparison rather than generating new fingerprints, significantly reducing real-time computational overhead
Solution Approach 2:
The invention extracts only the essential algorithm preference information from the full SSH client configuration and generates fingerprints based on this subset. This extraction approach reduces the amount of data that needs to be hashed and compared, thereby reducing computational overhead while maintaining verification reliability
3Adaptability or versatility
If HASSH fingerprints are used to identify SSH clients, then granular access control is achieved, but the complexity of the SSH protocol increases
Solution Approach 1:
The HASSH fingerprint mechanism serves multiple functions within the SSH protocol: it provides client identification, authenticity verification, and access control authorization all through a single fingerprint comparison process. This multi-functionality achieves granular access control without proportionally increasing protocol complexity, as the same fingerprint mechanism handles multiple security requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances security by ensuring that only authorized SSH clients and servers with known fingerprints can establish secure connections, preventing malicious activities such as data exfiltration and brute-force attacks, while also providing a granular level of access control and non-repudiation.
Implementation Method 1
performing a cryptographic hash on the set of supported algorithms, such as key exchange, encryption, message authentication, and compression algorithms
Data Source
AI summary
Techniques and structures to facilitate identification, authentication, authorization and accounting of a computing device is disclosed. A set of supported algorithms for transmission during a secure shell (SSH) clear packet exchange is received and a cryptographic hash is performed on the set of algorithms to generate a unique fingerprint.