Method Encrypt

xmlenc/pubkey.go:32–93

Encrypt implements encrypter. certificate must be a []byte containing the ASN.1 bytes of certificate containing an RSA public key.

(certificate interface{}, plaintext []byte, nonce []byte)

// Encrypt implements encrypter. certificate must be a []byte containing the ASN.1 bytes
// of certificate containing an RSA public key.
func (e RSA) Encrypt(certificate interface{}, plaintext []byte, nonce []byte) (*etree.Element, error) {
	cert, ok := certificate.(*x509.Certificate)
	if !ok {
		return nil, ErrIncorrectKeyType("*x.509 certificate")
	}

	pubKey, ok := cert.PublicKey.(*rsa.PublicKey)
	if !ok {
		return nil, ErrIncorrectKeyType("x.509 certificate with an RSA public key")
	}

	// generate a key
	key := make([]byte, e.BlockCipher.KeySize())
	if _, err := RandReader.Read(key); err != nil {
		return nil, err
	}

	keyInfoEl := etree.NewElement("ds:KeyInfo")
	keyInfoEl.CreateAttr("xmlns:ds", "http://www.w3.org/2000/09/xmldsig#")

	encryptedKey := keyInfoEl.CreateElement("xenc:EncryptedKey")
	{
		randBuf := make([]byte, 16)
		if _, err := RandReader.Read(randBuf); err != nil {
			return nil, err
		}
		encryptedKey.CreateAttr("Id", fmt.Sprintf("_%x", randBuf))
	}
	encryptedKey.CreateAttr("xmlns:xenc", "http://www.w3.org/2001/04/xmlenc#")

	encryptionMethodEl := encryptedKey.CreateElement("xenc:EncryptionMethod")
	encryptionMethodEl.CreateAttr("Algorithm", e.algorithm)
	encryptionMethodEl.CreateAttr("xmlns:xenc", "http://www.w3.org/2001/04/xmlenc#")
	if e.DigestMethod != nil {
		dm := encryptionMethodEl.CreateElement("ds:DigestMethod")
		dm.CreateAttr("Algorithm", e.DigestMethod.Algorithm())
		dm.CreateAttr("xmlns:ds", "http://www.w3.org/2000/09/xmldsig#")
	}
	{
		innerKeyInfoEl := encryptedKey.CreateElement("ds:KeyInfo")
		x509data := innerKeyInfoEl.CreateElement("ds:X509Data")
		x509data.CreateElement("ds:X509Certificate").SetText(
			base64.StdEncoding.EncodeToString(cert.Raw),
		)
	}

	buf, err := e.keyEncrypter(e, pubKey, key)
	if err != nil {
		return nil, err
	}

	cd := encryptedKey.CreateElement("xenc:CipherData")
	cd.CreateAttr("xmlns:xenc", "http://www.w3.org/2001/04/xmlenc#")
	cd.CreateElement("xenc:CipherValue").SetText(base64.StdEncoding.EncodeToString(buf))
	encryptedDataEl, err := e.BlockCipher.Encrypt(key, plaintext, nonce)
	if err != nil {
		return nil, err
	}