Creating keys - AWS Key Management Service

Creating keys

You can create symmetric and asymmetric AWS KMS keys in the AWS Management Console or by using the CreateKey operation. During this process, you determine the cryptographic configuration of your KMS key and the origin of the key material. You cannot change these properties after the KMS key is created. You also set the key policy for the KMS key, which you can change at any time.

If you are creating a KMS key to encrypt data you store or manage in an AWS service, create a symmetric KMS key. AWS services that are integrated with AWS KMS use symmetric KMS keys to encrypt your data. These services do not support encryption with asymmetric KMS keys. For help deciding which type of KMS key to create, see Choosing your KMS key configuration.

When you create a KMS key in the AWS KMS console, you are required to give it an alias (friendly name). The CreateKey operation does not create an alias for the new KMS key. To create an alias for a new or existing KMS key, use the CreateAlias operation. For detailed information about aliases in AWS KMS, see Using aliases.

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Permissions for creating KMS keys

To create a KMS key in the console or by using the APIs, you must have the following permission in an IAM policy. Whenever possible, use condition keys to limit the permissions. For an example of an IAM policy for principals who create keys, see Allow a user to create KMS keys.

Note

Be cautious when giving principals permission to manage tags and aliases. Changing a tag or alias can allow or deny permission to the customer managed key. For details, see Using ABAC for AWS KMS.

The kms:PutKeyPolicy permission is not required to create the KMS key. The kms:CreateKey permission includes permission to set the initial key policy. But you must add this permission to the key policy while creating the KMS key to ensure that you can control access to the KMS key. The alternative is using the BypassLockoutSafetyCheck parameter, which is not recommended.

Creating symmetric KMS key

You can create symmetric KMS key in the AWS Management Console or by using the AWS KMS API. Symmetric key encryption uses the same key to encrypt and decrypt data.

You can use the AWS Management Console to create AWS KMS keys (KMS keys).

  1. Sign in to the AWS Management Console and open the AWS Key Management Service (AWS KMS) console at https://console.aws.amazon.com/kms.

  2. To change the AWS Region, use the Region selector in the upper-right corner of the page.

  3. In the navigation pane, choose Customer managed keys.

  4. Choose Create key.

  5. To create a symmetric KMS key, for Key type choose Symmetric.

    For information about how to create an asymmetric KMS key in the AWS KMS console, see Creating asymmetric KMS keys (console).

  6. Choose Next.

  7. Type an alias for the KMS key. The alias name cannot begin with aws/. The aws/ prefix is reserved by Amazon Web Services to represent AWS managed keys in your account.

    Note

    Adding, deleting, or updating an alias can allow or deny permission to the KMS key. For details, see Using ABAC for AWS KMS and Using aliases to control access to KMS keys.

    An alias is a display name that you can use to identify the KMS key. We recommend that you choose an alias that indicates the type of data you plan to protect or the application you plan to use with the KMS key.

    Aliases are required when you create a KMS key in the AWS Management Console. They are optional when you use the CreateKey operation.

  8. (Optional) Type a description for the KMS key.

    You can add a description now or update it any time unless the key state is Pending Deletion or Pending Replica Deletion. To add, change, or delete the description of an existing customer managed key, edit the description in the AWS Management Console or use the UpdateKeyDescription operation.

  9. Choose Next.

  10. (Optional) Type a tag key and an optional tag value. To add more than one tag to the KMS key, choose Add tag.

    Note

    Tagging or untagging a KMS key can allow or deny permission to the KMS key. For details, see Using ABAC for AWS KMS and Using tags to control access to KMS keys.

    When you add tags to your AWS resources, AWS generates a cost allocation report with usage and costs aggregated by tags. Tags can also be used to control access to a KMS key. For information about tagging KMS keys, see Tagging keys and Using ABAC for AWS KMS.

  11. Choose Next.

  12. Select the IAM users and roles that can administer the KMS key.

    Note

    IAM policies can give other IAM users and roles permission to manage the KMS key.

  13. (Optional) To prevent the selected IAM users and roles from deleting this KMS key, in the Key deletion section at the bottom of the page, clear the Allow key administrators to delete this key check box.

  14. Choose Next.

  15. Select the IAM users and roles that can use the KMS key for cryptographic operations.

    Note

    The AWS account (root user) has full permissions by default. As a result, any IAM policies can also give users and roles permission to use the KMS key for cryptographic operations.

  16. (Optional) You can allow other AWS accounts to use this KMS key for cryptographic operations. To do so, in the Other AWS accounts section at the bottom of the page, choose Add another AWS account and enter the AWS account identification number of an external account. To add multiple external accounts, repeat this step.

    Note

    To allow principals in the external accounts to use the KMS key, Administrators of the external account must create IAM policies that provide these permissions. For more information, see Allowing users in other accounts to use a KMS key.

  17. Choose Next.

  18. Review the key settings that you chose. You can still go back and change all settings.

  19. Choose Finish to create the KMS key.

You can use the CreateKey operation to create a new symmetric AWS KMS keys. These examples use the AWS Command Line Interface (AWS CLI), but you can use any supported programming language.

This operation has no required parameters. However, you might also want to use the Policy parameter to specify a key policy. You can change the key policy (PutKeyPolicy) and add optional elements, such as a description and tags at any time. Also, if you are creating a KMS key for imported key material or a KMS key in a custom key store, the Origin parameter is required.

The CreateKey operation doesn't let you specify an alias, but you can use the CreateAlias operation to create an alias for your new KMS key.

The following is an example of a call to the CreateKey operation with no parameters. This command uses all of the default values. It creates a symmetric KMS key for encrypting and decrypting with key material generated by AWS KMS.

$ aws kms create-key { "KeyMetadata": { "Origin": "AWS_KMS", "KeyId": "1234abcd-12ab-34cd-56ef-1234567890ab", "Description": "", "KeyManager": "CUSTOMER", "Enabled": true, "KeySpec": "SYMMETRIC_DEFAULT", "CustomerMasterKeySpec": "SYMMETRIC_DEFAULT", "KeyUsage": "ENCRYPT_DECRYPT", "KeyState": "Enabled", "CreationDate": 1502910355.475, "Arn": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab", "AWSAccountId": "111122223333", "MultiRegion": false "EncryptionAlgorithms": [ "SYMMETRIC_DEFAULT" ], } }

If you do not specify a key policy for your new KMS key, the default key policy that CreateKey applies differs from the default key policy that the console applies when you use it to create a new KMS key.

For example, this call to the GetKeyPolicy operation returns the key policy that CreateKey applies. It gives the AWS account access to the KMS key and allows it to create AWS Identity and Access Management (IAM) policies for the KMS key. For detailed information about IAM policies and key policies for KMS keys, see Authentication and access control for AWS KMS

$ aws kms get-key-policy --key-id 1234abcd-12ab-34cd-56ef-1234567890ab --policy-name default --output text { "Version" : "2012-10-17", "Id" : "key-default-1", "Statement" : [ { "Sid" : "Enable IAM policies", "Effect" : "Allow", "Principal" : { "AWS" : "arn:aws:iam::111122223333:root" }, "Action" : "kms:*", "Resource" : "*" } ] }

Creating asymmetric KMS keys

You can create asymmetric KMS keys in the AWS Management Console or by using the AWS KMS API. An asymmetric KMS key represents a public and private key pair that can be used for encryption or signing. The private key remains within AWS KMS. To download the public key for use outside of AWS KMS, see Downloading public keys.

When creating a KMS key to encrypt data that you store or manage in an AWS service, use a symmetric KMS key. AWS services that integrate with AWS KMS do not support asymmetric KMS keys. For help deciding whether to create a symmetric or asymmetric KMS key, see How to Choose Your KMS key Configuration.

You can use the AWS Management Console to create asymmetric AWS KMS keys (KMS keys). Each asymmetric KMS key represents a public and private key pair.

  1. Sign in to the AWS Management Console and open the AWS Key Management Service (AWS KMS) console at https://console.aws.amazon.com/kms.

  2. To change the AWS Region, use the Region selector in the upper-right corner of the page.

  3. In the navigation pane, choose Customer managed keys.

  4. Choose Create key.

  5. To create an asymmetric KMS key, in Key type, choose Asymmetric.

    For information about how to create an symmetric KMS key in the AWS KMS console, see Creating symmetric KMS keys (console).

  6. To create an asymmetric KMS key for public key encryption, in Key usage, choose Encrypt and decrypt. Or, to create an asymmetric KMS key for signing messages and verifying signatures, in Key usage, choose Sign and verify.

    For help choosing a key usage value, see Selecting the key usage.

  7. Select a specification (Key spec) for your asymmetric KMS key.

    Often the key spec that you select is determined by regulatory, security, or business requirements. It might also be influenced by the size of messages that you need to encrypt or sign. In general, longer encryption keys are more resistant to brute-force attacks.

    For help choosing a key spec, see Selecting the key spec.

  8. Choose Next.

  9. Type an alias for the KMS key. The alias name cannot begin with aws/. The aws/ prefix is reserved by Amazon Web Services to represent AWS managed keys in your account.

    An alias is a friendly name that you can use to identify the KMS key in the console and in some AWS KMS APIs. We recommend that you choose an alias that indicates the type of data you plan to protect or the application you plan to use with the KMS key.

    Aliases are required when you create a KMS key in the AWS Management Console. You cannot specify an alias when you use the CreateKey operation, but you can use the console or the CreateAlias operation to create an alias for an existing KMS key. For details, see Using aliases.

  10. (Optional) Type a description for the KMS key.

    Enter a description that explains the type of data you plan to protect or the application you plan to use with the KMS key.

    You can add a description now or update it any time unless the key state is Pending Deletion or Pending Replica Deletion. To add, change, or delete the description of an existing customer managed key, edit the description in the AWS Management Console or use the UpdateKeyDescription operation.

  11. (Optional) Type a tag key and an optional tag value. To add more than one tag to the KMS key, choose Add tag.

    When you add tags to your AWS resources, AWS generates a cost allocation report with usage and costs aggregated by tags. Tags can also be used to control access to a KMS key. For information about tagging KMS keys, see Tagging keys and Using ABAC for AWS KMS.

  12. Choose Next.

  13. Select the IAM users and roles that can administer the KMS key.

    Note

    IAM policies can give other IAM users and roles permission to manage the KMS key.

  14. (Optional) To prevent the selected IAM users and roles from deleting this KMS key, in the Key deletion section at the bottom of the page, clear the Allow key administrators to delete this key check box.

  15. Choose Next.

  16. Select the IAM users and roles that can use the KMS key for cryptographic operations.

    Note

    The AWS account (root user) has full permissions by default. As a result, any IAM policies can also give users and roles permission use the KMS key for cryptographic operations.

  17. (Optional) You can allow other AWS accounts to use this KMS key for cryptographic operations. To do so, in the Other AWS accounts section at the bottom of the page, choose Add another AWS account and enter the AWS account identification number of an external account. To add multiple external accounts, repeat this step.

    Note

    To allow principals in the external accounts to use the KMS key, Administrators of the external account must create IAM policies that provide these permissions. For more information, see Allowing users in other accounts to use a KMS key.

  18. Choose Next.

  19. Review the key settings that you chose. You can still go back and change all settings.

  20. Choose Finish to create the KMS key.

You can use the CreateKey operation to create an asymmetric AWS KMS key. These examples use the AWS Command Line Interface (AWS CLI), but you can use any supported programming language.

When you create an asymmetric KMS key, you must specify the KeySpec parameter, which determines the type of keys you create. Also, you must specify a KeyUsage value of ENCRYPT_DECRYPT or SIGN_VERIFY. You cannot change these properties after the KMS key is created.

The CreateKey operation doesn't let you specify an alias, but you can use the CreateAlias operation to create an alias for your new KMS key.

The following example uses the CreateKey operation to create an asymmetric KMS key of 4096-bit RSA keys designed for public key encryption.

$ aws kms create-key --key-spec RSA_4096 --key-usage ENCRYPT_DECRYPT { "KeyMetadata": { "KeyState": "Enabled", "KeyId": "1234abcd-12ab-34cd-56ef-1234567890ab", "KeyManager": "CUSTOMER", "Description": "", "Arn": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab", "CreationDate": 1569973196.214, "MultiRegion": false, "KeySpec": "RSA_4096", "CustomerMasterKeySpec": "RSA_4096", "KeyUsage": "ENCRYPT_DECRYPT", "EncryptionAlgorithms": [ "RSAES_OAEP_SHA_1", "RSAES_OAEP_SHA_256" ], "AWSAccountId": "111122223333", "Origin": "AWS_KMS", "Enabled": true } }

The following example command creates an asymmetric KMS key that represents a pair of ECDSA keys used for signing and verification. You cannot create an elliptic curve key pair for encryption and decryption.

$ aws kms create-key --key-spec ECC_NIST_P521 --key-usage SIGN_VERIFY { "KeyMetadata": { "KeyState": "Enabled", "KeyId": "0987dcba-09fe-87dc-65ba-ab0987654321", "CreationDate": 1570824817.837, "Origin": "AWS_KMS", "SigningAlgorithms": [ "ECDSA_SHA_512" ], "Arn": "arn:aws:kms:us-west-2:111122223333:key/0987dcba-09fe-87dc-65ba-ab0987654321", "AWSAccountId": "111122223333", "KeySpec": "ECC_NIST_P521", "CustomerMasterKeySpec": "ECC_NIST_P521", "KeyManager": "CUSTOMER", "Description": "", "Enabled": true, "MultiRegion": false, "KeyUsage": "SIGN_VERIFY" } }