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.
77 lines
2.7 KiB
Go
77 lines
2.7 KiB
Go
// Copyright (c) 2020-2022 Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package atomic
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import (
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"math"
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"strconv"
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)
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//go:generate bin/gen-atomicwrapper -name=Float32 -type=float32 -wrapped=Uint32 -pack=math.Float32bits -unpack=math.Float32frombits -swap -json -imports math -file=float32.go
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// Add atomically adds to the wrapped float32 and returns the new value.
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func (f *Float32) Add(delta float32) float32 {
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for {
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old := f.Load()
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new := old + delta
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if f.CAS(old, new) {
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return new
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}
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}
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}
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// Sub atomically subtracts from the wrapped float32 and returns the new value.
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func (f *Float32) Sub(delta float32) float32 {
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return f.Add(-delta)
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}
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// CAS is an atomic compare-and-swap for float32 values.
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//
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// Deprecated: Use CompareAndSwap
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func (f *Float32) CAS(old, new float32) (swapped bool) {
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return f.CompareAndSwap(old, new)
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}
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// CompareAndSwap is an atomic compare-and-swap for float32 values.
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//
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// Note: CompareAndSwap handles NaN incorrectly. NaN != NaN using Go's inbuilt operators
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// but CompareAndSwap allows a stored NaN to compare equal to a passed in NaN.
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// This avoids typical CompareAndSwap loops from blocking forever, e.g.,
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//
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// for {
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// old := atom.Load()
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// new = f(old)
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// if atom.CompareAndSwap(old, new) {
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// break
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// }
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// }
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//
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// If CompareAndSwap did not match NaN to match, then the above would loop forever.
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func (f *Float32) CompareAndSwap(old, new float32) (swapped bool) {
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return f.v.CompareAndSwap(math.Float32bits(old), math.Float32bits(new))
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}
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// String encodes the wrapped value as a string.
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func (f *Float32) String() string {
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// 'g' is the behavior for floats with %v.
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return strconv.FormatFloat(float64(f.Load()), 'g', -1, 32)
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}
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