mirror of
https://github.com/cheat/cheat.git
synced 2024-11-17 01:18:29 +01:00
80c91cbdee
Integrate `go-git` into the application, and use it to `git clone` cheatsheets when the installer runs. Previously, the installer required that `git` be installed on the system `PATH`, so this change has to big advantages: 1. It removes that system dependency on `git` 2. It paves the way for implementing the `--update` command Additionally, `cheat` now performs a `--depth=1` clone when installing cheatsheets, which should at least somewhat improve installation times (especially on slow network connections).
46 lines
1.1 KiB
Go
46 lines
1.1 KiB
Go
package x448
|
|
|
|
import (
|
|
"crypto/subtle"
|
|
|
|
fp "github.com/cloudflare/circl/math/fp448"
|
|
)
|
|
|
|
// Size is the length in bytes of a X448 key.
|
|
const Size = 56
|
|
|
|
// Key represents a X448 key.
|
|
type Key [Size]byte
|
|
|
|
func (k *Key) clamp(in *Key) *Key {
|
|
*k = *in
|
|
k[0] &= 252
|
|
k[55] |= 128
|
|
return k
|
|
}
|
|
|
|
// isValidPubKey verifies if the public key is not a low-order point.
|
|
func (k *Key) isValidPubKey() bool {
|
|
fp.Modp((*fp.Elt)(k))
|
|
isLowOrder := false
|
|
for _, P := range lowOrderPoints {
|
|
isLowOrder = isLowOrder || subtle.ConstantTimeCompare(P[:], k[:]) != 0
|
|
}
|
|
return !isLowOrder
|
|
}
|
|
|
|
// KeyGen obtains a public key given a secret key.
|
|
func KeyGen(public, secret *Key) {
|
|
ladderJoye(public.clamp(secret))
|
|
}
|
|
|
|
// Shared calculates Alice's shared key from Alice's secret key and Bob's
|
|
// public key returning true on success. A failure case happens when the public
|
|
// key is a low-order point, thus the shared key is all-zeros and the function
|
|
// returns false.
|
|
func Shared(shared, secret, public *Key) bool {
|
|
validPk := *public
|
|
ok := validPk.isValidPubKey()
|
|
ladderMontgomery(shared.clamp(secret), &validPk)
|
|
return ok
|
|
}
|