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.
81 lines
2.5 KiB
Go
81 lines
2.5 KiB
Go
// Copyright 2024 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package proto
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// ValueOrNil returns nil if has is false, or a pointer to a new variable
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// containing the value returned by the specified getter.
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//
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// This function is similar to the wrappers (proto.Int32(), proto.String(),
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// etc.), but is generic (works for any field type) and works with the hasser
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// and getter of a field, as opposed to a value.
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//
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// This is convenient when populating builder fields.
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//
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// Example:
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//
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// hop := attr.GetDirectHop()
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// injectedRoute := ripb.InjectedRoute_builder{
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// Prefixes: route.GetPrefixes(),
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// NextHop: proto.ValueOrNil(hop.HasAddress(), hop.GetAddress),
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// }
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func ValueOrNil[T any](has bool, getter func() T) *T {
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if !has {
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return nil
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}
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v := getter()
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return &v
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}
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// ValueOrDefault returns the protobuf message val if val is not nil, otherwise
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// it returns a pointer to an empty val message.
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//
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// This function allows for translating code from the old Open Struct API to the
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// new Opaque API.
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//
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// The old Open Struct API represented oneof fields with a wrapper struct:
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//
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// var signedImg *accountpb.SignedImage
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// profile := &accountpb.Profile{
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// // The Avatar oneof will be set, with an empty SignedImage.
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// Avatar: &accountpb.Profile_SignedImage{signedImg},
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// }
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//
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// The new Opaque API treats oneof fields like regular fields, there are no more
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// wrapper structs:
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//
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// var signedImg *accountpb.SignedImage
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// profile := &accountpb.Profile{}
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// profile.SetSignedImage(signedImg)
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//
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// For convenience, the Opaque API also offers Builders, which allow for a
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// direct translation of struct initialization. However, because Builders use
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// nilness to represent field presence (but there is no non-nil wrapper struct
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// anymore), Builders cannot distinguish between an unset oneof and a set oneof
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// with nil message. The above code would need to be translated with help of the
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// ValueOrDefault function to retain the same behavior:
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//
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// var signedImg *accountpb.SignedImage
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// return &accountpb.Profile_builder{
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// SignedImage: proto.ValueOrDefault(signedImg),
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// }.Build()
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func ValueOrDefault[T interface {
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*P
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Message
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}, P any](val T) T {
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if val == nil {
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return T(new(P))
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}
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return val
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}
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// ValueOrDefaultBytes is like ValueOrDefault but for working with fields of
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// type []byte.
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func ValueOrDefaultBytes(val []byte) []byte {
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if val == nil {
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return []byte{}
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}
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return val
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}
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