mirror of
https://github.com/rclone/rclone.git
synced 2024-12-02 21:37:31 +01:00
6427029c4e
* Update all dependencies * Remove all `[[constraint]]` from Gopkg.toml * Add in the minimum number of `[[override]]` to build * Remove go get of github.com/inconshreveable/mousetrap as it is vendored * Update docs with new policy on constraints
84 lines
3.2 KiB
Go
84 lines
3.2 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// Package sign signs small messages using public-key cryptography.
|
|
//
|
|
// Sign uses Ed25519 to sign messages. The length of messages is not hidden.
|
|
// Messages should be small because:
|
|
// 1. The whole message needs to be held in memory to be processed.
|
|
// 2. Using large messages pressures implementations on small machines to process
|
|
// plaintext without verifying the signature. This is very dangerous, and this API
|
|
// discourages it, but a protocol that uses excessive message sizes might present
|
|
// some implementations with no other choice.
|
|
// 3. Performance may be improved by working with messages that fit into data caches.
|
|
// Thus large amounts of data should be chunked so that each message is small.
|
|
//
|
|
// This package is not interoperable with the current release of NaCl
|
|
// (https://nacl.cr.yp.to/sign.html), which does not support Ed25519 yet. However,
|
|
// it is compatible with the NaCl fork libsodium (https://www.libsodium.org), as well
|
|
// as TweetNaCl (https://tweetnacl.cr.yp.to/).
|
|
package sign
|
|
|
|
import (
|
|
"io"
|
|
|
|
"golang.org/x/crypto/ed25519"
|
|
)
|
|
|
|
// Overhead is the number of bytes of overhead when signing a message.
|
|
const Overhead = 64
|
|
|
|
// GenerateKey generates a new public/private key pair suitable for use with
|
|
// Sign and Open.
|
|
func GenerateKey(rand io.Reader) (publicKey *[32]byte, privateKey *[64]byte, err error) {
|
|
pub, priv, err := ed25519.GenerateKey(rand)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
publicKey, privateKey = new([32]byte), new([64]byte)
|
|
copy((*publicKey)[:], pub)
|
|
copy((*privateKey)[:], priv)
|
|
return publicKey, privateKey, nil
|
|
}
|
|
|
|
// Sign appends a signed copy of message to out, which will be Overhead bytes
|
|
// longer than the original and must not overlap it.
|
|
func Sign(out, message []byte, privateKey *[64]byte) []byte {
|
|
sig := ed25519.Sign(ed25519.PrivateKey((*privateKey)[:]), message)
|
|
ret, out := sliceForAppend(out, Overhead+len(message))
|
|
copy(out, sig)
|
|
copy(out[Overhead:], message)
|
|
return ret
|
|
}
|
|
|
|
// Open verifies a signed message produced by Sign and appends the message to
|
|
// out, which must not overlap the signed message. The output will be Overhead
|
|
// bytes smaller than the signed message.
|
|
func Open(out, signedMessage []byte, publicKey *[32]byte) ([]byte, bool) {
|
|
if len(signedMessage) < Overhead {
|
|
return nil, false
|
|
}
|
|
if !ed25519.Verify(ed25519.PublicKey((*publicKey)[:]), signedMessage[Overhead:], signedMessage[:Overhead]) {
|
|
return nil, false
|
|
}
|
|
ret, out := sliceForAppend(out, len(signedMessage)-Overhead)
|
|
copy(out, signedMessage[Overhead:])
|
|
return ret, true
|
|
}
|
|
|
|
// sliceForAppend takes a slice and a requested number of bytes. It returns a
|
|
// slice with the contents of the given slice followed by that many bytes and a
|
|
// second slice that aliases into it and contains only the extra bytes. If the
|
|
// original slice has sufficient capacity then no allocation is performed.
|
|
func sliceForAppend(in []byte, n int) (head, tail []byte) {
|
|
if total := len(in) + n; cap(in) >= total {
|
|
head = in[:total]
|
|
} else {
|
|
head = make([]byte, total)
|
|
copy(head, in)
|
|
}
|
|
tail = head[len(in):]
|
|
return
|
|
}
|