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.
99 lines
3.2 KiB
Go
99 lines
3.2 KiB
Go
// Copyright 2019 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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import (
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"google.golang.org/protobuf/encoding/protowire"
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"google.golang.org/protobuf/internal/encoding/messageset"
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"google.golang.org/protobuf/internal/errors"
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"google.golang.org/protobuf/internal/flags"
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"google.golang.org/protobuf/internal/order"
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"google.golang.org/protobuf/reflect/protoreflect"
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"google.golang.org/protobuf/reflect/protoregistry"
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)
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func (o MarshalOptions) sizeMessageSet(m protoreflect.Message) (size int) {
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m.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
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size += messageset.SizeField(fd.Number())
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size += protowire.SizeTag(messageset.FieldMessage)
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size += protowire.SizeBytes(o.size(v.Message()))
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return true
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})
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size += messageset.SizeUnknown(m.GetUnknown())
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return size
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}
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func (o MarshalOptions) marshalMessageSet(b []byte, m protoreflect.Message) ([]byte, error) {
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if !flags.ProtoLegacy {
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return b, errors.New("no support for message_set_wire_format")
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}
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fieldOrder := order.AnyFieldOrder
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if o.Deterministic {
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fieldOrder = order.NumberFieldOrder
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}
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var err error
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order.RangeFields(m, fieldOrder, func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
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b, err = o.marshalMessageSetField(b, fd, v)
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return err == nil
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})
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if err != nil {
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return b, err
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}
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return messageset.AppendUnknown(b, m.GetUnknown())
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}
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func (o MarshalOptions) marshalMessageSetField(b []byte, fd protoreflect.FieldDescriptor, value protoreflect.Value) ([]byte, error) {
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b = messageset.AppendFieldStart(b, fd.Number())
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b = protowire.AppendTag(b, messageset.FieldMessage, protowire.BytesType)
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calculatedSize := o.Size(value.Message().Interface())
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b = protowire.AppendVarint(b, uint64(calculatedSize))
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before := len(b)
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b, err := o.marshalMessage(b, value.Message())
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if err != nil {
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return b, err
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}
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if measuredSize := len(b) - before; calculatedSize != measuredSize {
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return nil, errors.MismatchedSizeCalculation(calculatedSize, measuredSize)
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}
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b = messageset.AppendFieldEnd(b)
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return b, nil
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}
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func (o UnmarshalOptions) unmarshalMessageSet(b []byte, m protoreflect.Message) error {
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if !flags.ProtoLegacy {
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return errors.New("no support for message_set_wire_format")
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}
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return messageset.Unmarshal(b, false, func(num protowire.Number, v []byte) error {
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err := o.unmarshalMessageSetField(m, num, v)
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if err == errUnknown {
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unknown := m.GetUnknown()
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unknown = protowire.AppendTag(unknown, num, protowire.BytesType)
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unknown = protowire.AppendBytes(unknown, v)
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m.SetUnknown(unknown)
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return nil
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}
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return err
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})
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}
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func (o UnmarshalOptions) unmarshalMessageSetField(m protoreflect.Message, num protowire.Number, v []byte) error {
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md := m.Descriptor()
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if !md.ExtensionRanges().Has(num) {
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return errUnknown
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}
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xt, err := o.Resolver.FindExtensionByNumber(md.FullName(), num)
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if err == protoregistry.NotFound {
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return errUnknown
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}
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if err != nil {
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return errors.New("%v: unable to resolve extension %v: %v", md.FullName(), num, err)
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}
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xd := xt.TypeDescriptor()
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if err := o.unmarshalMessage(v, m.Mutable(xd).Message()); err != nil {
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return err
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}
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return nil
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}
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