PutKeyPolicy 搭配 AWS SDK 或 CLI 使用

變更 KMS 金鑰的金鑰政策

下列put-key-policy範例會變更客戶受管金鑰的金鑰政策。

若要開始，請建立金鑰政策並將其儲存在本機 JSON 檔案中。在此範例中，檔案為 key_policy.json。您也可以指定金鑰政策做為 policy 參數的字串值。

此金鑰政策中的第一個陳述式提供 AWS 帳戶使用 IAM 政策來控制對 KMS 金鑰的存取的許可。第二個陳述式提供test-user使用者在 KMS 金鑰上執行 describe-key和 list-keys命令的許可。

key_policy.json 的內容：

{
    "Version" : "2012-10-17",
    "Id" : "key-default-1",
    "Statement" : [
        {
            "Sid" : "Enable IAM User Permissions",
            "Effect" : "Allow",
            "Principal" : {
                "AWS" : "arn:aws:iam::111122223333:root"
            },
            "Action" : "kms:*",
            "Resource" : "*"
        },
        {
            "Sid" : "Allow Use of Key",
            "Effect" : "Allow",
            "Principal" : {
                "AWS" : "arn:aws:iam::111122223333:user/test-user"
            },
            "Action" : [
                "kms:DescribeKey",
                "kms:ListKeys"
            ],
            "Resource" : "*"
        }
    ]
}

若要識別 KMS 金鑰，此範例會使用金鑰 ID，但您也可以使用金鑰 ARN。若要指定金鑰政策，命令會使用 policy 參數。若要指出政策位於 檔案，會使用必要的file://字首。識別所有支援的作業系統上的檔案時，需要此字首。最後， 命令會使用 值為 的 policy-name 參數default。如果未指定政策名稱，預設值為 default。唯一有效的值為 default。

aws kms put-key-policy \
    --policy-name default \
    --key-id 1234abcd-12ab-34cd-56ef-1234567890ab \
    --policy file://key_policy.json

此命令不會產生任何輸出。若要驗證命令是否有效，請使用 get-key-policy命令。下列範例命令會取得相同 KMS 金鑰的金鑰政策。值為 的 output 參數會text傳回易於讀取的文字格式。

aws kms get-key-policy \
    --policy-name default \
    --key-id 1234abcd-12ab-34cd-56ef-1234567890ab \
    --output text

輸出：

{
    "Version" : "2012-10-17",
    "Id" : "key-default-1",
    "Statement" : [
        {
            "Sid" : "Enable IAM User Permissions",
            "Effect" : "Allow",
            "Principal" : {
                "AWS" : "arn:aws:iam::111122223333:root"
            },
            "Action" : "kms:*",
            "Resource" : "*"
            },
            {
            "Sid" : "Allow Use of Key",
            "Effect" : "Allow",
            "Principal" : {
                "AWS" : "arn:aws:iam::111122223333:user/test-user"
            },
            "Action" : [ "kms:Describe", "kms:List" ],
            "Resource" : "*"
        }
    ]
}

如需詳細資訊，請參閱 金鑰管理服務開發人員指南中的變更金鑰政策。 AWS

    /***
     * @param string $keyId
     * @param string $policy
     * @return void
     */
    public function putKeyPolicy(string $keyId, string $policy)
    {
        try {
            $this->client->putKeyPolicy([
                'KeyId' => $keyId,
                'Policy' => $policy,
            ]);
        }catch(KmsException $caught){
            echo "There was a problem replacing the key policy: {$caught->getAwsErrorMessage()}\n";
            throw $caught;
        }
    }

class KeyPolicy:
    def __init__(self, kms_client):
        self.kms_client = kms_client

    @classmethod
    def from_client(cls) -> "KeyPolicy":
        """
        Creates a KeyPolicy instance with a default KMS client.

        :return: An instance of KeyPolicy initialized with the default KMS client.
        """
        kms_client = boto3.client("kms")
        return cls(kms_client)


    def set_policy(self, key_id: str, policy: dict[str, any]) -> None:
        """
        Sets the policy of a key. Setting a policy entirely overwrites the existing
        policy, so care is taken to add a statement to the existing list of statements
        rather than simply writing a new policy.

        :param key_id: The ARN or ID of the key to set the policy to.
        :param policy: The existing policy of the key.
        :return: None
        """
        principal = input(
            "Enter the ARN of an IAM role to set as the principal on the policy: "
        )
        if key_id != "" and principal != "":
            # The updated policy replaces the existing policy. Add a new statement to
            # the list along with the original policy statements.
            policy["Statement"].append(
                {
                    "Sid": "Allow access for ExampleRole",
                    "Effect": "Allow",
                    "Principal": {"AWS": principal},
                    "Action": [
                        "kms:Encrypt",
                        "kms:GenerateDataKey*",
                        "kms:Decrypt",
                        "kms:DescribeKey",
                        "kms:ReEncrypt*",
                    ],
                    "Resource": "*",
                }
            )
            try:
                self.kms_client.put_key_policy(KeyId=key_id, Policy=json.dumps(policy))
            except ClientError as err:
                logger.error(
                    "Couldn't set policy for key %s. Here's why %s",
                    key_id,
                    err.response["Error"]["Message"],
                )
                raise
            else:
                print(f"Set policy for key {key_id}.")
        else:
            print("Skipping set policy demo.")