4d9a26498e
Paste a secret, get a link, send it. The first person to open it and press
Reveal sees the secret; the link dies at that moment. The recipient needs a
browser and nothing else — no account, no client, no installed tooling.
The server cannot read what it stores. AES-256-GCM happens in the browser and
the key lives in the URL fragment, which browsers never transmit, so hushd
holds ciphertext and no key material. That is a property of where the key sits
rather than a promise about our conduct, which is why there is deliberately no
endpoint accepting a plaintext secret and no server-side-encryption fallback:
two guarantees behind one URL would be worse than one honest guarantee.
Three decisions carry the design:
* GET /s/{id} touches NO storage, not even to check existence. Slack, Teams,
WhatsApp, iMessage and Outlook Safe Links all fetch a URL before a human
sees it, so destroying on GET would destroy most secrets in transit and the
recipient's "already used" would be indistinguishable from interception.
Only POST /reveal consumes. Bot user-agent detection is an arms race;
removing the side effect from GET is not. Pinned by
TestGettingTheRevealPageNeverConsumesTheSecret.
* Destruction is one Redis GETDEL, which is atomic. GET-then-DEL has a window
where two simultaneous readers both win, and for a one-time secret that
window is the product. The store contract demands atomicity and the same
concurrency test runs against both implementations.
* Missing, already-revealed, expired and evicted are ONE indistinguishable
410. Separating them would confirm to a prober that a given link was real.
The secret id IS the capability, so secret.ID is a struct whose every
accidental path — %v, %s, String(), slog, json.Marshal — emits a redacted
handle or refuses, and the raw value needs an explicit Value(). The first
version tried to prevent leaks by implementing no String() at all; its own test
caught that Go's fmt prints unexported fields anyway, so forbidding the method
had removed the control rather than the leak.
Operationally: structured JSON on stdout in the fleet's wire format, which
Vector already collects with no annotation; six hush_* metrics on the chassis
registry with no id, IP or path in any label; five alert rules wired into
vmalert. The public Ingress enumerates /, /s/ and /api/ so /metrics, /healthz
and /readyz share the port but are unreachable from the internet — no
basic-auth middleware to maintain and get wrong.
Dependencies are vendored because go-chassis is private: the Woodpecker test
step and the in-cluster Kaniko build both run -mod=vendor with GOPROXY=off and
hold no git credential.
cmd/hush-mcp is a stdio MCP server doing the same client-side crypto locally,
so using hush from an agent preserves the same guarantee as using it from a
browser.
45 lines
1.2 KiB
Go
45 lines
1.2 KiB
Go
package chassis
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import "strconv"
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// Page is a parsed cursor-pagination request (?limit=&cursor=). Cursor is opaque
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// to the chassis; handlers encode/decode it (e.g. an id or keyset token).
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type Page struct {
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Limit int
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Cursor string
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}
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// Page parses pagination params from the query string, clamping limit to
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// [1, maxLimit] and defaulting to defLimit.
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func (c *Context) Page(defLimit, maxLimit int) Page {
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q := c.r.URL.Query()
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p := Page{Limit: defLimit, Cursor: q.Get("cursor")}
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if v := q.Get("limit"); v != "" {
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if n, err := strconv.Atoi(v); err == nil && n > 0 {
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p.Limit = n
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}
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}
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if p.Limit > maxLimit {
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p.Limit = maxLimit
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}
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if p.Limit < 1 {
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p.Limit = 1
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}
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return p
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}
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// ListResponse is the standard list envelope. NextCursor is "" on the last page.
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type ListResponse[T any] struct {
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Items []T `json:"items"`
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NextCursor string `json:"next_cursor,omitempty"`
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}
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// List builds a ListResponse, normalizing a nil slice to []. nextCursor is the
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// token a client passes as ?cursor= to fetch the next page ("" = no more).
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func List[T any](items []T, nextCursor string) ListResponse[T] {
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if items == nil {
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items = []T{}
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}
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return ListResponse[T]{Items: items, NextCursor: nextCursor}
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}
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