code: func (csp *CSP) Encrypt(k bccsp.Key, plaintext []byte, opts bccsp.EncrypterOpts) ([]byte, error) {
  	// Validate arguments
  	if k == nil {
  		return nil, errors.New("Invalid Key. It must not be nil.")
  	}
  
  	encryptor, found := csp.Encryptors[reflect.TypeOf(k)]
  	if !found {
  		return nil, errors.Errorf("Unsupported 'EncryptKey' provided [%v]", k)
  	}
  
  	return encryptor.Encrypt(k, plaintext, opts)
  }
docs: // Encrypt encrypts plaintext using key k.
  // The opts argument should be appropriate for the primitive used.