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.
87 lines
2.8 KiB
Go
87 lines
2.8 KiB
Go
// Copyright 2009 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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//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
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// Package unix contains an interface to the low-level operating system
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// primitives. OS details vary depending on the underlying system, and
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// by default, godoc will display OS-specific documentation for the current
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// system. If you want godoc to display OS documentation for another
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// system, set $GOOS and $GOARCH to the desired system. For example, if
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// you want to view documentation for freebsd/arm on linux/amd64, set $GOOS
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// to freebsd and $GOARCH to arm.
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//
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// The primary use of this package is inside other packages that provide a more
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// portable interface to the system, such as "os", "time" and "net". Use
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// those packages rather than this one if you can.
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//
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// For details of the functions and data types in this package consult
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// the manuals for the appropriate operating system.
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//
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// These calls return err == nil to indicate success; otherwise
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// err represents an operating system error describing the failure and
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// holds a value of type syscall.Errno.
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package unix // import "golang.org/x/sys/unix"
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import (
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"bytes"
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"strings"
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"unsafe"
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)
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// ByteSliceFromString returns a NUL-terminated slice of bytes
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// containing the text of s. If s contains a NUL byte at any
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// location, it returns (nil, EINVAL).
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func ByteSliceFromString(s string) ([]byte, error) {
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if strings.IndexByte(s, 0) != -1 {
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return nil, EINVAL
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}
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a := make([]byte, len(s)+1)
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copy(a, s)
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return a, nil
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}
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// BytePtrFromString returns a pointer to a NUL-terminated array of
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// bytes containing the text of s. If s contains a NUL byte at any
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// location, it returns (nil, EINVAL).
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func BytePtrFromString(s string) (*byte, error) {
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a, err := ByteSliceFromString(s)
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if err != nil {
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return nil, err
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}
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return &a[0], nil
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}
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// ByteSliceToString returns a string form of the text represented by the slice s, with a terminating NUL and any
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// bytes after the NUL removed.
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func ByteSliceToString(s []byte) string {
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if i := bytes.IndexByte(s, 0); i != -1 {
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s = s[:i]
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}
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return string(s)
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}
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// BytePtrToString takes a pointer to a sequence of text and returns the corresponding string.
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// If the pointer is nil, it returns the empty string. It assumes that the text sequence is terminated
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// at a zero byte; if the zero byte is not present, the program may crash.
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func BytePtrToString(p *byte) string {
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if p == nil {
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return ""
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}
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if *p == 0 {
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return ""
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}
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// Find NUL terminator.
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n := 0
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for ptr := unsafe.Pointer(p); *(*byte)(ptr) != 0; n++ {
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ptr = unsafe.Pointer(uintptr(ptr) + 1)
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}
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return string(unsafe.Slice(p, n))
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}
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// Single-word zero for use when we need a valid pointer to 0 bytes.
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var _zero uintptr
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