Hash-Validation-Security-and-Robustness-Enhancement

[Kwin-xeexee]

Description

Hash-Validation-Security-and-Robustness-Enhancement
This PR enhances the security and robustness of the hash validation system by introducing consistent validation rules, strengthening resistance against timing attacks, and enforcing a canonical hash representation across the service.

Changes Made

• Implemented constant-time hash comparison to mitigate timing attack vulnerabilities.
• Introduced a unified CanonicalHash type to enforce consistent hash formatting and validation.
• Standardized hash validation across all service boundaries.
• Added validation to ensure submitted hashes are compatible with Stellar memo requirements.
• Implemented duplicate hash detection through a hash registry.
• Improved hash validation logic to provide consistent behavior across supported algorithms.
• Added documentation describing hash security guarantees and validation behavior.

Why

The previous implementation had several security and consistency gaps, including:

• Timing attack exposure during hash comparisons.
• Inconsistent support for hashing algorithms across validation paths.
• No canonical representation of hashes throughout the application.
• Missing validation for document hash format and Stellar memo compatibility.
• Potential duplicate hash submissions.
• Limited documentation around the security properties of hash validation.

These improvements provide a more secure, predictable, and maintainable validation pipeline.

Testing

• Added tests for constant-time hash validation.
• Verified canonical hash normalization across supported formats.
• Tested duplicate hash detection.
• Validated Stellar memo compatibility.
• Verified supported hashing algorithms behave consistently.
• Confirmed all existing validation flows continue to function correctly.

Related Issue

Closes #44

[MaryammAli]

LGTM