code: private CipherParameters getCipherParameters(KeyType keyType) {
  		switch (keyType) {
  		case PublicKey:
  			return this.publicKeyParams;
  		case PrivateKey:
  			return this.privateKeyParams;
  		}
  
  		return null;
  	}
docs: 获取密钥类型对应的加密参数对象{@link CipherParameters}
  
  @param keyType Key类型枚举，包括私钥或公钥
  @return {@link CipherParameters}