dazai — burn-after-reading secret (motokano)

CI docs License: MIT

Burn-after-reading secrets for AI agents.

ningen-shikkaku ships two small Rust binaries — dazai (the session-bound daemon) and motokano (a self-immolating one-shot MCP server).

Your MCP configs are full of plaintext API keys, and every agent you run can read all of them — and they keep working long after the agent is done. dazai inverts that: secrets live in locked, non-swappable RAM, are served to agents over MCP, and are destroyed after N reads — or the instant your session dies.

motokano --calls 1 --tool 'name=get_key,kind=static,value=s3cr3t' --arm

Point any MCP client at it and call get_key once → you receive s3cr3t → the server wipes the value out of locked memory and SIGKILLs itself. Call again → the process is gone.

Install

# prebuilt binaries (macOS arm64/x86_64, Linux x86_64/arm64)
curl --proto '=https' --tlsv1.2 -LsSf https://github.com/New1Direction/ningen-shikkaku/releases/latest/download/dazai-installer.sh | sh

# or homebrew
brew install New1Direction/tap/dazai New1Direction/tap/motokano

# or from source (required for the Linux seccomp build)
git clone https://github.com/New1Direction/ningen-shikkaku
cd ningen-shikkaku/rs
cargo build --release                       # -> target/release/{dazai, motokano}
cargo build --release --features seccomp    # Linux: seccomp syscall allowlist

Prebuilt binaries are built with default features; the seccomp-confined daemon is a from-source build (it links libseccomp — install libseccomp-dev + pkg-config first).

Use it with Claude Code

# a one-shot secret an agent can read exactly once:
claude mcp add burn-once -- motokano --calls 1 --arm \
  --tool 'name=get_key,kind=static,value=YOUR-SECRET'

# or the session-bound daemon: agents register their PID and get SIGKILLed
# the moment your session dies
dazai daemon --arm --grace 5 &
claude mcp add dazai -- dazai mcp

Any MCP client works the same way — the transport is plain stdio.

And the second act: a dead-man's switch for your agents

The same daemon is a session kill-switch. Any MCP client registers its PID; when your shell/SSH session dies, your heartbeat stops, or a panic signal arrives, dazai SIGKILLs every registered process, overwrites its secrets with a wipe the compiler can't optimize away, and exits. Walk away: agents die, secrets burn.

dazai daemon --ping-timeout 15        # terminal A  (dry-run by default; --arm makes it real)
dazai client --interval 5             # terminal B
# close terminal B  ->  the daemon wipes its secrets and exits

It runs only on your own machine, on your own secrets and your own configured tools. It never touches another process, file, or host.

What's in the box

It ships in two layers:

• a hardened Rust daemon + tooling — the real thing: mlock (no swap), madvise(MADV_DONTDUMP) + prctl(PR_SET_DUMPABLE, 0) (no core dumps / no ptrace), a seccomp syscall allowlist (no execve/open/connect/…), and a non-elidable explicit_bzero / memset_s wipe; and
• a Python reference implementation — the original proof-of-concept that established the mechanism (see python-reference.md).

Component	What it does
dazai daemon	The watchdog: holds mlock'd secrets + a UNIX-socket heartbeat; wipes and self-destructs on session loss. seccomp-confined on Linux.
dazai client	The heartbeat client — ties the daemon's life to a shell / SSH session.
dazai mcp	An MCP server exposing the daemon as tools, so any agent can register its PID for session-bound protection (it gets SIGKILLed if your session dies).
motokano	A standalone self-immolating MCP server: serve N tool calls, then wipe secret state and exit.
Python reference	secmem.py / deadman.py / heartbeat.py / shellrc.sh — the portable proof-of-concept.

Architecture

flowchart LR
    A["MCP client / AI agent<br/>(stdio transport)"]

    subgraph Daemon["dazai daemon (kikka Watchdog)"]
        D["dazai daemon<br/>mlock'd SecretBuffers (goodnight)<br/>seccomp-confined on Linux (kekkai)"]
        SOCK[("UNIX socket 0600<br/>HELLO heartbeat + REGISTER / ARM / STATUS")]
    end

    MCPD["dazai mcp<br/>(rei · rmcp server)"]
    HB["dazai client<br/>(heartbeat: HELLO / PING)"]
    MOTO["motokano<br/>(self-immolating MCP server)<br/>static values in SecretBuffer"]
    KILL{{"wipe (explicit_bzero / memset_s)<br/>+ SIGKILL"}}

    A -->|"register pid / status / panic"| MCPD
    A -->|"get_key (static, N reads)"| MOTO
    MCPD -->|"relay verbs + signals via pidfile"| SOCK
    HB -->|"holds liveness connection"| SOCK
    SOCK --- D
    MOTO -. "optional --dazai-socket: register + monitor" .-> SOCK
    D ==>|"on trigger: SIGKILL registered PIDs, then wipe + self-SIGKILL"| KILL
    MOTO ==>|"after N calls / EOF / daemon death: wipe + exit"| KILL
    HB -. "drop / ping-timeout / panic signal" .-> D

Threat model

daZai shrinks the window and the surface in which plaintext secrets are reachable, and makes session-end deterministically destroy them.

It protects against:

Risk	How
Secrets paged to swap	mlock locks the buffers into RAM
Secrets captured in core dumps	madvise(MADV_DONTDUMP) + prctl(PR_SET_DUMPABLE, 0) (Linux)
Session loss leaving secrets resident	heartbeat drop / logout → wipe + SIGKILL
Secrets lingering in process memory after use	explicit_bzero / memset_s — a wipe the compiler may not elide
A confined process escaping	seccomp allowlist denies execve / open / connect / ptrace / … (Linux)
ptrace snooping the daemon	prctl(PR_SET_DUMPABLE, 0) (Linux)

It does NOT protect against (and the project is deliberately honest about this):

• GPU VRAM. If an attached LLM/agent copies a secret into GPU memory, killing the host process does not wipe VRAM. daZai controls host RAM and the processes it supervises — not an accelerator's memory.
• exec-tool stdout. motokano's kind=exec tools return a command's stdout, which is OS-buffered and not held in a locked buffer. Use kind=static (a pre-loaded, locked, wipeable value) when you need the wipe guarantee.
• Managed-runtime residue (Python reference). CPython copies bytes freely, so a secret may transiently live in unlocked heap before/after the locked buffer. The Rust implementation eliminates this for its own buffers (data is written into the locked mapping and never copied to a GC heap); the Python tier is a reference, not a hard guarantee.
• A privileged or same-UID attacker on the live box (root, /proc/<pid>/mem, a debugger) reading memory before the wipe. mlock stops swap, not memory reads; seccomp + PR_SET_DUMPABLE raise the bar on Linux, but an adversary who already has privileged access to your running machine is out of scope.
• Cold-boot / DMA / physical attacks on RAM.
• A hard crash (kernel OOM, an external kill -9, power loss): the wipe path can't run, so nothing is zeroed. The mechanism is best-effort on these paths and never claims otherwise.

In short: daZai is not, and cannot be, a guarantee against an attacker who already owns your running machine. It is a sharp tool for making secrets ephemeral and session-bound, with every limitation stated up front.

Verification

• 66 tests across the Rust workspace (secure memory, the panic policy, the wire protocol, the MCP layer, the one-shot lifecycle) plus the 29-test Python reference.
• Linux seccomp is validated on both architectures under the real KillProcess filter — aarch64 (locally) and x86_64 (CI) — where the daemon installs the live filter and the full integration suite runs against it with no SIGSYS.
• Every push runs the whole suite (default and --features seccomp), clippy -D warnings, and rustfmt --check on x86_64 Linux as a permanent regression gate.

Deep technical docs (per-crate design, the seccomp allowlist, the adversarial-review history) live in rs/README.md; the Python proof-of-concept is in python-reference.md.

The name

Named for the novelist Osamu Dazai, whose work circles themes of disappearance and self-erasure — fitting for software whose defining act is to wipe itself out the moment it is no longer being watched over. The repository takes its name from his novel No Longer Human (人間失格, Ningen Shikkaku). It's flavor, not a manifesto; the software just self-destructs on cue.

License

MIT © 2026 New1Direction.