hashlogged

Hashlogged is a concept in data integrity and security logging that describes a method for producing tamper-evident logs by embedding cryptographic hashes into the logging process. In a hashlogged system, each log entry includes a hash that links to previous entries, creating a chain or tree of hashes that can be verified later. The goal is to detect any alteration of past records while keeping the logging process practical for ordinary use.

Mechanism and verification: When a new entry is written, its content is hashed and combined with the hash of the preceding entry. The log may store the raw data alongside the hash chain, or use a Merkle tree to summarize a set of entries with a single root hash. Verification involves recomputing the hashes through the chain or tree and ensuring the links are intact and that the final root or timestamp matches a trusted anchor.

Relation to related concepts: Hashlogged builds on ideas such as hash chains, hashed logs, and append-only logs. It is primarily an integrity and verifiability mechanism rather than a method for protecting confidentiality. In some implementations, digital signatures or trusted time-stamps are added to authenticate the origin of log entries and to anchor the log to external authorities.

Advantages and challenges: Hashlogged can provide tamper-evidence, enable audits, and support remote verification. Trade-offs include storage and processing overhead for hashing, the need for reliable time sources or anchors, and the complexity of managing keys and verification tools.

Applications: Hashlogged is considered for security and system logs, compliance reporting, incident response, and distributed event sourcing where an immutable, auditable trail is required.