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.
100 lines
3.0 KiB
Go
100 lines
3.0 KiB
Go
// Copyright 2013 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package model
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import (
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"encoding/json"
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"errors"
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"fmt"
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"math"
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"strconv"
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)
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// ZeroSamplePair is the pseudo zero-value of SamplePair used to signal a
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// non-existing sample pair. It is a SamplePair with timestamp Earliest and
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// value 0.0. Note that the natural zero value of SamplePair has a timestamp
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// of 0, which is possible to appear in a real SamplePair and thus not
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// suitable to signal a non-existing SamplePair.
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var ZeroSamplePair = SamplePair{Timestamp: Earliest}
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// A SampleValue is a representation of a value for a given sample at a given
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// time.
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type SampleValue float64
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// MarshalJSON implements json.Marshaler.
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func (v SampleValue) MarshalJSON() ([]byte, error) {
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return json.Marshal(v.String())
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}
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// UnmarshalJSON implements json.Unmarshaler.
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func (v *SampleValue) UnmarshalJSON(b []byte) error {
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if len(b) < 2 || b[0] != '"' || b[len(b)-1] != '"' {
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return errors.New("sample value must be a quoted string")
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}
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f, err := strconv.ParseFloat(string(b[1:len(b)-1]), 64)
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if err != nil {
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return err
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}
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*v = SampleValue(f)
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return nil
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}
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// Equal returns true if the value of v and o is equal or if both are NaN. Note
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// that v==o is false if both are NaN. If you want the conventional float
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// behavior, use == to compare two SampleValues.
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func (v SampleValue) Equal(o SampleValue) bool {
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if v == o {
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return true
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}
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return math.IsNaN(float64(v)) && math.IsNaN(float64(o))
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}
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func (v SampleValue) String() string {
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return strconv.FormatFloat(float64(v), 'f', -1, 64)
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}
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// SamplePair pairs a SampleValue with a Timestamp.
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type SamplePair struct {
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Timestamp Time
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Value SampleValue
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}
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func (s SamplePair) MarshalJSON() ([]byte, error) {
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t, err := json.Marshal(s.Timestamp)
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if err != nil {
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return nil, err
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}
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v, err := json.Marshal(s.Value)
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if err != nil {
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return nil, err
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}
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return fmt.Appendf(nil, "[%s,%s]", t, v), nil
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}
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// UnmarshalJSON implements json.Unmarshaler.
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func (s *SamplePair) UnmarshalJSON(b []byte) error {
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v := [...]json.Unmarshaler{&s.Timestamp, &s.Value}
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return json.Unmarshal(b, &v)
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}
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// Equal returns true if this SamplePair and o have equal Values and equal
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// Timestamps. The semantics of Value equality is defined by SampleValue.Equal.
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func (s *SamplePair) Equal(o *SamplePair) bool {
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return s == o || (s.Value.Equal(o.Value) && s.Timestamp.Equal(o.Timestamp))
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}
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func (s SamplePair) String() string {
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return fmt.Sprintf("%s @[%s]", s.Value, s.Timestamp)
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}
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