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.
106 lines
2.5 KiB
Go
106 lines
2.5 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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"fmt"
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"strconv"
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)
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// Fingerprint provides a hash-capable representation of a Metric.
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// For our purposes, FNV-1A 64-bit is used.
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type Fingerprint uint64
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// FingerprintFromString transforms a string representation into a Fingerprint.
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func FingerprintFromString(s string) (Fingerprint, error) {
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num, err := strconv.ParseUint(s, 16, 64)
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return Fingerprint(num), err
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}
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// ParseFingerprint parses the input string into a fingerprint.
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func ParseFingerprint(s string) (Fingerprint, error) {
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num, err := strconv.ParseUint(s, 16, 64)
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if err != nil {
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return 0, err
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}
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return Fingerprint(num), nil
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}
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func (f Fingerprint) String() string {
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return fmt.Sprintf("%016x", uint64(f))
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}
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// Fingerprints represents a collection of Fingerprint subject to a given
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// natural sorting scheme. It implements sort.Interface.
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type Fingerprints []Fingerprint
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// Len implements sort.Interface.
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func (f Fingerprints) Len() int {
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return len(f)
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}
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// Less implements sort.Interface.
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func (f Fingerprints) Less(i, j int) bool {
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return f[i] < f[j]
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}
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// Swap implements sort.Interface.
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func (f Fingerprints) Swap(i, j int) {
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f[i], f[j] = f[j], f[i]
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}
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// FingerprintSet is a set of Fingerprints.
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type FingerprintSet map[Fingerprint]struct{}
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// Equal returns true if both sets contain the same elements (and not more).
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func (s FingerprintSet) Equal(o FingerprintSet) bool {
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if len(s) != len(o) {
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return false
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}
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for k := range s {
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if _, ok := o[k]; !ok {
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return false
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}
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}
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return true
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}
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// Intersection returns the elements contained in both sets.
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func (s FingerprintSet) Intersection(o FingerprintSet) FingerprintSet {
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myLength, otherLength := len(s), len(o)
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if myLength == 0 || otherLength == 0 {
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return FingerprintSet{}
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}
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subSet := s
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superSet := o
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if otherLength < myLength {
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subSet = o
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superSet = s
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}
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out := FingerprintSet{}
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for k := range subSet {
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if _, ok := superSet[k]; ok {
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out[k] = struct{}{}
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}
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}
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return out
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}
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