112 lines
4.6 KiB
Bash
Executable File
112 lines
4.6 KiB
Bash
Executable File
#!/usr/bin/env bash
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set -euo pipefail
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# Verify CASAN H5 append-only hash-chain audit log.
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# Usage:
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# verify-audit-chain.sh [audit-jsonl]
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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source "$SCRIPT_DIR/casan-paths.sh"
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PROJECT_ROOT="$CASAN_APP_ROOT"
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AUDIT_LOG="${1:-$CASAN_STATE_ROOT/logs/audit/audit.jsonl}"
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if [[ ! -f "$AUDIT_LOG" ]]; then
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echo "AUDIT_CHAIN_MISSING file=$AUDIT_LOG" >&2
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exit 1
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fi
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COMPUTED_HEAD="$(python - "$AUDIT_LOG" <<'PY'
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import hashlib
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import json
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import sys
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path = sys.argv[1]
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previous = ""
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count = 0
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with open(path, encoding="utf-8") as f:
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for line_no, line in enumerate(f, 1):
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if not line.strip():
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continue
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record = json.loads(line)
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expected_previous = record.get("previous_record_hash", "")
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if expected_previous != previous:
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raise SystemExit(
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f"AUDIT_CHAIN_BROKEN line={line_no} expected_previous={previous} actual_previous={expected_previous}"
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)
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if int(record.get("schema_version", 1)) >= 2:
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core = "|".join([
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record.get("timestamp", ""), record.get("trace_id", ""),
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record.get("action", ""), record.get("action_class", ""),
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record.get("actor", ""), record.get("risk_level", ""),
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json.dumps(record.get("risk_factors", {}), sort_keys=True, separators=(",", ":")),
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record.get("evidence_requirement", ""), record.get("decision", ""),
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record.get("approval_status", ""), record.get("approver", ""),
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record.get("input_hash", ""), record.get("output_hash", ""),
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expected_previous,
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])
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else:
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core = "|".join(
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[
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record.get("timestamp", ""), record.get("trace_id", ""),
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record.get("action", ""), record.get("actor", ""),
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record.get("risk_level", ""), record.get("decision", ""),
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record.get("approval_status", ""), record.get("approver", ""),
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record.get("input_hash", ""), record.get("output_hash", ""),
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expected_previous,
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]
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)
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expected_hash = hashlib.sha256(core.encode()).hexdigest()
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actual_hash = record.get("record_hash", "")
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if expected_hash != actual_hash:
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raise SystemExit(
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f"AUDIT_HASH_MISMATCH line={line_no} expected={expected_hash} actual={actual_hash}"
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)
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previous = actual_hash
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count += 1
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# Emit count and head on stderr (human) and the head on stdout (captured).
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sys.stderr.write(f"AUDIT_CHAIN_INTEGRITY_OK records={count}\n")
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sys.stdout.write(previous)
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PY
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)"
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# --- External anchor verification ---
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# Recomputing a forged chain yields a different head; the stored head signature
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# was produced with a private key the forger does not have, so it will not match.
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AUDIT_DIR="$(dirname "$AUDIT_LOG")"
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HEAD_FILE="$AUDIT_DIR/audit-head.txt"
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HEAD_SIG="$AUDIT_DIR/audit-head.sig"
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AUDIT_PUB="$CASAN_GOVERNANCE_ROOT/audit-public.pem"
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if [[ -f "$HEAD_FILE" && -f "$HEAD_SIG" && -f "$AUDIT_PUB" ]] && command -v openssl >/dev/null 2>&1; then
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STORED_HEAD="$(cat "$HEAD_FILE")"
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if [[ "$STORED_HEAD" != "$COMPUTED_HEAD" ]]; then
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echo "AUDIT_HEAD_MISMATCH computed=$COMPUTED_HEAD stored=$STORED_HEAD" >&2
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exit 1
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fi
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if ! openssl dgst -sha256 -verify "$AUDIT_PUB" -signature "$HEAD_SIG" "$HEAD_FILE" >/dev/null 2>&1; then
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echo "AUDIT_HEAD_SIGNATURE_INVALID head=$COMPUTED_HEAD" >&2
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exit 1
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fi
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echo "AUDIT_CHAIN_VALID anchor=signed last_hash=$COMPUTED_HEAD"
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else
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# SEC-01 (H-01): in enforced mode a missing/unverifiable signature is a FAILURE,
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# not "valid unsigned". Otherwise deleting audit-head.sig (or the pubkey) after
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# tampering + recomputing the chain would pass verification. Permissive mode
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# (dev default) keeps the previous unsigned-OK behaviour. Self-contained check
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# (this script is copied into sandboxes by tests, so it must not source common.sh):
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# CASAN_PROFILE=prod (SEC-17) enables all enforce flags; CASAN_VERIFY_STRICT=1 this one.
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if [[ "${CASAN_PROFILE:-}" == "prod" || "${CASAN_VERIFY_STRICT:-}" == "1" ]]; then
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MISSING=""
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[[ -f "$HEAD_FILE" ]] || MISSING="$MISSING head-file"
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[[ -f "$HEAD_SIG" ]] || MISSING="$MISSING head-sig"
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[[ -f "$AUDIT_PUB" ]] || MISSING="$MISSING pubkey"
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command -v openssl >/dev/null 2>&1 || MISSING="$MISSING openssl"
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echo "AUDIT_CHAIN_UNSIGNED_STRICT_FAIL last_hash=$COMPUTED_HEAD missing=${MISSING# }" >&2
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exit 1
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fi
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echo "AUDIT_CHAIN_VALID anchor=unsigned last_hash=$COMPUTED_HEAD"
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fi
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