Method Encrypt

xmlenc/cbc.go:34–78

Encrypt encrypts plaintext with key, which should be a []byte of length KeySize(). It returns an xenc:EncryptedData element.

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

// Encrypt encrypts plaintext with key, which should be a []byte of length KeySize().
// It returns an xenc:EncryptedData element.
func (e CBC) Encrypt(key interface{}, plaintext []byte, nonce []byte) (*etree.Element, error) {
	keyBuf, ok := key.([]byte)
	if !ok {
		return nil, ErrIncorrectKeyType("[]byte")
	}
	if len(keyBuf) != e.keySize {
		return nil, ErrIncorrectKeyLength(e.keySize)
	}

	block, err := e.cipher(keyBuf)
	if err != nil {
		return nil, err
	}

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

	em := encryptedDataEl.CreateElement("xenc:EncryptionMethod")
	em.CreateAttr("Algorithm", e.algorithm)
	em.CreateAttr("xmlns:xenc", "http://www.w3.org/2001/04/xmlenc#")

	plaintext = appendPadding(plaintext, block.BlockSize())

	iv := make([]byte, block.BlockSize())
	if _, err := RandReader.Read(iv); err != nil {
		return nil, err
	}

	mode := cipher.NewCBCEncrypter(block, iv)
	ciphertext := make([]byte, len(plaintext))
	mode.CryptBlocks(ciphertext, plaintext)
	ciphertext = append(iv, ciphertext...)

	cd := encryptedDataEl.CreateElement("xenc:CipherData")
	cd.CreateAttr("xmlns:xenc", "http://www.w3.org/2001/04/xmlenc#")
	cd.CreateElement("xenc:CipherValue").SetText(base64.StdEncoding.EncodeToString(ciphertext))
	return encryptedDataEl, nil
}

// Decrypt decrypts an encrypted element with key. If the ciphertext contains an
// EncryptedKey element, then the type of `key` is determined by the registered