portainer/api/chisel/crypto/crypto.go

62 lines
1.5 KiB
Go

package crypto
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/x509"
"encoding/pem"
"fmt"
"io"
"math/big"
chshare "github.com/jpillora/chisel/share"
)
var one = new(big.Int).SetInt64(1)
// GenerateGo119CompatibleKey This function is basically copied from chshare.GenerateKey.
func GenerateGo119CompatibleKey(seed string) ([]byte, error) {
r := chshare.NewDetermRand([]byte(seed))
priv, err := ecdsaGenerateKey(elliptic.P256(), r)
if err != nil {
return nil, err
}
b, err := x509.MarshalECPrivateKey(priv)
if err != nil {
return nil, fmt.Errorf("Unable to marshal ECDSA private key: %w", err)
}
return pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: b}), nil
}
// This function is copied from Go1.19
func randFieldElement(c elliptic.Curve, rand io.Reader) (k *big.Int, err error) {
params := c.Params()
// Note that for P-521 this will actually be 63 bits more than the order, as
// division rounds down, but the extra bit is inconsequential.
b := make([]byte, params.N.BitLen()/8+8)
_, err = io.ReadFull(rand, b)
if err != nil {
return
}
k = new(big.Int).SetBytes(b)
n := new(big.Int).Sub(params.N, one)
k.Mod(k, n)
k.Add(k, one)
return
}
// This function is copied from Go1.19
func ecdsaGenerateKey(c elliptic.Curve, rand io.Reader) (*ecdsa.PrivateKey, error) {
k, err := randFieldElement(c, rand)
if err != nil {
return nil, err
}
priv := new(ecdsa.PrivateKey)
priv.PublicKey.Curve = c
priv.D = k
priv.PublicKey.X, priv.PublicKey.Y = c.ScalarBaseMult(k.Bytes())
return priv, nil
}