hush — AI agents use secrets without ever seeing them

npm i -g --allow-scripts=hush-secrets hush-secrets  # installs binary + skill
hush set MY_API_KEY            # in YOUR terminal, never in chat
hush update                    # self-update from GitHub releases

Why

Pasting a secret into a harness chat leaves it in the transcript forever. hush separates the channels: the human loads values via TTY or the harness native prompt (over MCP), the agent only orchestrates names. No tool ever returns a value.

Related MCP server: keyper

MCP (harness-agnostic: claude, opencode, cursor, codex)

hush serve exposes stdio with 4 tools: hush_check, hush_list, hush_need (asks for the value via elicitation and stores it), hush_run (injects + redacts). hush setup installs the skill and shows how to register the server in each harness.

CLI

openssl rand -hex 24 | hush set WHATSAPP_VERIFY_TOKEN
hush check WHATSAPP_VERIFY_TOKEN META_APP_SECRET
hush stdin WHATSAPP_VERIFY_TOKEN -- npx wrangler secret put WHATSAPP_VERIFY_TOKEN
hush run --only META_APP_SECRET -- npx wrangler deploy
hush status

check and list print names only. run and stdin inject into the child process and redact output to [REDACTED].

Where secrets live, and getting them back

Values are stored in ~/.hush/vault (file 0600, dir 0700), one NAME=value per line. There is intentionally no read-back over MCP and no get command — anything an agent can call ends up in its context.

To recover a value (rotation, migration, backup), use a real terminal:

hush export                  # prints all, NAME=value per line
hush export META_APP_SECRET  # prints one

export refuses to run unless stdout is a TTY, so no harness can capture it by piping. Back up the file itself (cp ~/.hush/vault …) for disaster recovery; wipe with rm -rf ~/.hush. See SECURITY.md and PRIVACY.md.

Docs

SECURITY.md (threat model) · PRIVACY.md · CONTRIBUTING.md · CHANGELOG.md

Alternatives

*akm is macOS-only (Keychain). hush keeps a plain 0600 file so any dev can inspect, back up, and recover it with standard tools.

Development

make check   # generate + fmt + vet + test + build
make hook    # pre-commit (generate + fmt + vet + test)
./scripts/release.sh 0.2.0  # bump + tag (workflow publishes npm + release)

Conventional commits: feat:, fix:, chore:, docs:, refactor:, test:. SKILL.md is the single source of the skill; internal/setup/skill.md is regenerated with go generate ./... (a test enforces it).