diff --git a/README.md b/README.md index e8da9a5..d405ae5 100644 --- a/README.md +++ b/README.md @@ -20,7 +20,7 @@ trace "IR team gained shell access. Initial persistence checks running." trace "Observed outbound connection to 192.168.1.55 on port 80. #suspicious #network" ``` -**System Integrity Chain:** Each command-line note is immediately stamped, concatenated with its content, and hashed using SHA256 before storage. This ensures a non-repudiable log entry. +**System Integrity Chain:** Each command-line note is immediately stamped with a Unix epoch timestamp (seconds since 1970-01-01 00:00:00 UTC as float, e.g., `1702345678.123456`), concatenated with its content in the format `"{timestamp}:{content}"`, and hashed using SHA256 before storage. This ensures a non-repudiable log entry with forensically tamper-evident timestamps. ## CLI Command Reference @@ -195,7 +195,7 @@ After this, you can log with just: `t "Your note here"` | Feature | Description | Operational Impact | | :--- | :--- | :--- | -| **Integrity Hashing** | SHA256 applied to every log entry (content + timestamp). | **Guaranteed log integrity.** No modification possible post-entry. | +| **Integrity Hashing** | SHA256 applied to every log entry using format `"{unix_timestamp}:{content}"`. Timestamp is Unix epoch as float (e.g., `1702345678.123456`). | **Guaranteed log integrity.** No modification possible post-entry. Timestamps are forensically tamper-evident with full float precision. | | **GPG Signing** | Optional PGP/GPG signature applied to notes. | **Non-repudiation** for formal evidence handling. | | **IOC Extraction** | Automatic parsing of IPv4, FQDNs, URLs, hashes, and email addresses. | **Immediate intelligence gathering** from raw text. | | **Tag System** | Supports `#hashtags` for classification and filtering. | **Efficient triage** of large log sets. | @@ -208,20 +208,33 @@ After this, you can log with just: `t "Your note here"` ### Layer 1: Note-Level Integrity (Always Active) **Process:** -1. **Timestamp Generation** - Precise Unix timestamp captured at note creation -2. **Content Hashing** - SHA256 hash computed from `timestamp:content` +1. **Timestamp Generation** - Precise Unix epoch timestamp (float) captured at note creation + - Format: Seconds since 1970-01-01 00:00:00 UTC (e.g., `1702345678.123456`) + - Full float precision preserved for forensic tamper-evidence +2. **Content Hashing** - SHA256 hash computed from `"{timestamp}:{content}"` 3. **Optional Signature** - Hash is signed with investigator's GPG private key **Mathematical Representation:** ``` -hash = SHA256(timestamp + ":" + content) +timestamp = Unix epoch time as float (e.g., 1702345678.123456) +hash_input = "{timestamp}:{content}" +hash = SHA256(hash_input) signature = GPG_Sign(hash, private_key) ``` +**Example:** +``` +Content: "Suspicious process detected" +Timestamp: 1702345678.123456 +Hash input: "1702345678.123456:Suspicious process detected" +Hash: SHA256 of above = a3f5b2c8d9e1f4a7b6c3d8e2f5a9b4c7d1e6f3a8b5c2d9e4f7a1b8c6d3e0f5a2 +``` + **Security Properties:** - **Temporal Integrity**: Timestamp is cryptographically bound to content (cannot backdate notes) - **Tamper Detection**: Any modification to content or timestamp invalidates the hash - **Non-Repudiation**: GPG signature proves who created the note (if signing enabled) +- **Hash Reproducibility**: Exported markdown includes Unix timestamp for independent verification - **Efficient Storage**: Signing only the hash (64 hex chars) instead of full content ### Layer 2: Export-Level Integrity (On Demand) @@ -328,6 +341,26 @@ Individual note signatures are embedded in the markdown export. To verify a spec - The GPG signature proves who created that hash - Together: Proves this specific content was created by this investigator at this time +**Hash Verification (Manual):** + +To independently verify a note's hash from the markdown export: + +1. Locate the note in the export file and extract: + - Unix Timestamp (e.g., `1702345678.123456`) + - Content (e.g., `"Suspicious process detected"`) + - Claimed Hash (e.g., `a3f5b2c8...`) + +2. Recompute the hash: + ```bash + # Using Python + python3 -c "import hashlib; print(hashlib.sha256(b'1702345678.123456:Suspicious process detected').hexdigest())" + + # Using command-line tools + echo -n "1702345678.123456:Suspicious process detected" | sha256sum + ``` + +3. Compare the computed hash with the claimed hash - they must match exactly + ### Cryptographic Trust Model ``` diff --git a/trace/cli.py b/trace/cli.py index 79a6f64..1f5a3cb 100644 --- a/trace/cli.py +++ b/trace/cli.py @@ -364,9 +364,14 @@ def export_markdown(output_file: str = "export.md"): sys.exit(1) def format_note_for_export(note: Note) -> str: - """Format a single note for export (returns string instead of writing to file)""" + """Format a single note for export (returns string instead of writing to file) + + Includes Unix timestamp for hash reproducibility - anyone can recompute the hash + using the formula: SHA256("{unix_timestamp}:{content}") + """ lines = [] lines.append(f"- **{time.ctime(note.timestamp)}**\n") + lines.append(f" - Unix Timestamp: `{note.timestamp}` (for hash verification)\n") lines.append(f" - Content:\n") # Properly indent multi-line content for line in note.content.splitlines():