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path: root/crypto.go
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package acme

import (
	"crypto"
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/base64"
	"encoding/pem"
	"errors"
	"io"
	"io/ioutil"
)

const (
	pemRSA = `RSA PRIVATE KEY`
	pemEC  = `EC PRIVATE KEY`
	pemCRT = `CERTIFICATE`
)

var errKeyType = errors.New("unknown key type")

func SaveKey(w io.Writer, key crypto.PrivateKey) error {
	var block *pem.Block
	switch k := key.(type) {
	case *rsa.PrivateKey:
		der := x509.MarshalPKCS1PrivateKey(k)
		block = &pem.Block{Type: pemRSA, Bytes: der}
	case *ecdsa.PrivateKey:
		der, err := x509.MarshalECPrivateKey(k)
		if err != nil {
			return err
		}
		block = &pem.Block{Type: pemEC, Bytes: der}
	}
	return pem.Encode(w, block)
}

func LoadKey(r io.Reader) (crypto.PrivateKey, error) {
	der, err := ioutil.ReadAll(r)
	if err != nil {
		return nil, err
	}
	block, _ := pem.Decode(der)
	switch block.Type {
	case pemRSA:
		return x509.ParsePKCS1PrivateKey(block.Bytes)
	case pemEC:
		return x509.ParseECPrivateKey(block.Bytes)
	default:
		return nil, errKeyType
	}
}

func SaveCert(w io.Writer, cert []byte) error {
	block := &pem.Block{
		Type:  pemCRT,
		Bytes: cert,
	}
	return pem.Encode(w, block)
}

func LoadCerts(r io.Reader) ([]*x509.Certificate, error) {
	der, err := ioutil.ReadAll(r)
	if err != nil {
		return nil, err
	}
	block, _ := pem.Decode(der)
	return x509.ParseCertificates(block.Bytes)
}

func NewKey(size int) (crypto.PrivateKey, error) {
	if size == 0 {
		return ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
	}
	return rsa.GenerateKey(rand.Reader, size)
}

func NewCSR(key crypto.PrivateKey, altnames []string) (string, error) {
	tmpl := x509.CertificateRequest{
		Subject: pkix.Name{CommonName: altnames[0]},
	}
	if len(altnames) > 1 {
		tmpl.DNSNames = altnames
	}
	der, err := x509.CreateCertificateRequest(rand.Reader, &tmpl, key)
	if err != nil {
		return "", err
	}
	return base64.RawURLEncoding.EncodeToString(der), nil
}