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KMS  >  Operations  >  create_key

create_key

Operation

create_key async 

create_key(input: CreateKeyInput, plugins: list[Plugin] | None = None) -> CreateKeyOutput

Creates a unique customer managed KMS key in your Amazon Web Services account and Region. You can use a KMS key in cryptographic operations, such as encryption and signing. Some Amazon Web Services services let you use KMS keys that you create and manage to protect your service resources.

A KMS key is a logical representation of a cryptographic key. In addition to the key material used in cryptographic operations, a KMS key includes metadata, such as the key ID, key policy, creation date, description, and key state.

Use the parameters of CreateKey to specify the type of KMS key, the source of its key material, its key policy, description, tags, and other properties.

Note

KMS has replaced the term customer master key (CMK) with Key Management Service key and KMS key. The concept has not changed. To prevent breaking changes, KMS is keeping some variations of this term.

To create different types of KMS keys, use the following guidance:

Symmetric encryption KMS key

By default, CreateKey creates a symmetric encryption KMS key with key material that KMS generates. This is the basic and most widely used type of KMS key, and provides the best performance.

To create a symmetric encryption KMS key, you don't need to specify any parameters. The default value for KeySpec, SYMMETRIC_DEFAULT, the default value for KeyUsage, ENCRYPT_DECRYPT, and the default value for Origin, AWS_KMS, create a symmetric encryption KMS key with KMS key material.

If you need a key for basic encryption and decryption or you are creating a KMS key to protect your resources in an Amazon Web Services service, create a symmetric encryption KMS key. The key material in a symmetric encryption key never leaves KMS unencrypted. You can use a symmetric encryption KMS key to encrypt and decrypt data up to 4,096 bytes, but they are typically used to generate data keys and data keys pairs. For details, see GenerateDataKey and GenerateDataKeyPair.

Asymmetric KMS keys

To create an asymmetric KMS key, use the KeySpec parameter to specify the type of key material in the KMS key. Then, use the KeyUsage parameter to determine whether the KMS key will be used to encrypt and decrypt or sign and verify. You can't change these properties after the KMS key is created.

Asymmetric KMS keys contain an RSA key pair, Elliptic Curve (ECC) key pair, ML-DSA key pair or an SM2 key pair (China Regions only). The private key in an asymmetric KMS key never leaves KMS unencrypted. However, you can use the GetPublicKey operation to download the public key so it can be used outside of KMS. Each KMS key can have only one key usage. KMS keys with RSA key pairs can be used to encrypt and decrypt data or sign and verify messages (but not both). KMS keys with NIST-standard ECC key pairs can be used to sign and verify messages or derive shared secrets (but not both). KMS keys with ECC_SECG_P256K1 can be used only to sign and verify messages. KMS keys with ML-DSA key pairs can be used to sign and verify messages. KMS keys with SM2 key pairs (China Regions only) can be used to either encrypt and decrypt data, sign and verify messages, or derive shared secrets (you must choose one key usage type). For information about asymmetric KMS keys, see Asymmetric KMS keys in the Key Management Service Developer Guide.

HMAC KMS key

To create an HMAC KMS key, set the KeySpec parameter to a key spec value for HMAC KMS keys. Then set the KeyUsage parameter to GENERATE_VERIFY_MAC. You must set the key usage even though GENERATE_VERIFY_MAC is the only valid key usage value for HMAC KMS keys. You can't change these properties after the KMS key is created.

HMAC KMS keys are symmetric keys that never leave KMS unencrypted. You can use HMAC keys to generate (GenerateMac) and verify (VerifyMac) HMAC codes for messages up to 4096 bytes.

Multi-Region primary keys

To create a multi-Region primary key in the local Amazon Web Services Region, use the MultiRegion parameter with a value of True. To create a multi-Region replica key, that is, a KMS key with the same key ID and key material as a primary key, but in a different Amazon Web Services Region, use the ReplicateKey operation. To change a replica key to a primary key, and its primary key to a replica key, use the UpdatePrimaryRegion operation.

You can create multi-Region KMS keys for all supported KMS key types: symmetric encryption KMS keys, HMAC KMS keys, asymmetric encryption KMS keys, and asymmetric signing KMS keys. You can also create multi-Region keys with imported key material. However, you can't create multi-Region keys in a custom key store.

This operation supports multi-Region keys, an KMS feature that lets you create multiple interoperable KMS keys in different Amazon Web Services Regions. Because these KMS keys have the same key ID, key material, and other metadata, you can use them interchangeably to encrypt data in one Amazon Web Services Region and decrypt it in a different Amazon Web Services Region without re-encrypting the data or making a cross-Region call. For more information about multi-Region keys, see Multi-Region keys in KMS in the Key Management Service Developer Guide.

Imported key material

To import your own key material into a KMS key, begin by creating a KMS key with no key material. To do this, use the Origin parameter of CreateKey with a value of EXTERNAL. Next, use GetParametersForImport operation to get a public key and import token. Use the wrapping public key to encrypt your key material. Then, use ImportKeyMaterial with your import token to import the key material. For step-by-step instructions, see Importing Key Material in the Key Management Service Developer Guide .

You can import key material into KMS keys of all supported KMS key types: symmetric encryption KMS keys, HMAC KMS keys, asymmetric encryption KMS keys, and asymmetric signing KMS keys. You can also create multi-Region keys with imported key material. However, you can't import key material into a KMS key in a custom key store.

To create a multi-Region primary key with imported key material, use the Origin parameter of CreateKey with a value of EXTERNAL and the MultiRegion parameter with a value of True. To create replicas of the multi-Region primary key, use the ReplicateKey operation. For instructions, see Importing key material step 1. For more information about multi-Region keys, see Multi-Region keys in KMS in the Key Management Service Developer Guide.

Custom key store

A custom key store lets you protect your Amazon Web Services resources using keys in a backing key store that you own and manage. When you request a cryptographic operation with a KMS key in a custom key store, the operation is performed in the backing key store using its cryptographic keys.

KMS supports CloudHSM key stores backed by an CloudHSM cluster and external key stores backed by an external key manager outside of Amazon Web Services. When you create a KMS key in an CloudHSM key store, KMS generates an encryption key in the CloudHSM cluster and associates it with the KMS key. When you create a KMS key in an external key store, you specify an existing encryption key in the external key manager.

Note: Some external key managers provide a simpler method for creating a KMS key in an external key store. For details, see your external key manager documentation. Before you create a KMS key in a custom key store, the ConnectionState of the key store must be CONNECTED. To connect the custom key store, use the ConnectCustomKeyStore operation. To find the ConnectionState, use the DescribeCustomKeyStores operation.

To create a KMS key in a custom key store, use the CustomKeyStoreId. Use the default KeySpec value, SYMMETRIC_DEFAULT, and the default KeyUsage value, ENCRYPT_DECRYPT to create a symmetric encryption key. No other key type is supported in a custom key store.

To create a KMS key in an CloudHSM key store, use the Origin parameter with a value of AWS_CLOUDHSM. The CloudHSM cluster that is associated with the custom key store must have at least two active HSMs in different Availability Zones in the Amazon Web Services Region.

To create a KMS key in an external key store, use the Origin parameter with a value of EXTERNAL_KEY_STORE and an XksKeyId parameter that identifies an existing external key.

Note: Some external key managers provide a simpler method for creating a KMS key in an external key store. For details, see your external key manager documentation.

Cross-account use: No. You cannot use this operation to create a KMS key in a different Amazon Web Services account.

Required permissions: kms:CreateKey (IAM policy). To use the Tags parameter, kms:TagResource (IAM policy). For examples and information about related permissions, see Allow a user to create KMS keys in the Key Management Service Developer Guide.

Related operations:

  • DescribeKey

  • ListKeys

  • ScheduleKeyDeletion

Eventual consistency: The KMS API follows an eventual consistency model. For more information, see KMS eventual consistency.

Parameters:

Name Type Description Default
input CreateKeyInput

An instance of CreateKeyInput.

 required
plugins list[Plugin] | None

A list of callables that modify the configuration dynamically. Changes made by these plugins only apply for the duration of the operation execution and will not affect any other operation invocations.

 None

Returns:

Type Description
CreateKeyOutput

An instance of CreateKeyOutput.

Input

CreateKeyInput dataclass

Bases: _SerdeShape

Dataclass for CreateKeyInput structure.

Attributes

bypass_policy_lockout_safety_check class-attribute instance-attribute 
bypass_policy_lockout_safety_check: bool = ...

Skips ("bypasses") the key policy lockout safety check. The default value is false.

Warning

Setting this value to true increases the risk that the KMS key becomes unmanageable. Do not set this value to true indiscriminately.

For more information, see Default key policy in the Key Management Service Developer Guide.

Use this parameter only when you intend to prevent the principal that is making the request from making a subsequent PutKeyPolicy request on the KMS key.

custom_key_store_id class-attribute instance-attribute 
custom_key_store_id: str | None = ...

Creates the KMS key in the specified custom key store. The ConnectionState of the custom key store must be CONNECTED. To find the CustomKeyStoreID and ConnectionState use the DescribeCustomKeyStores operation.

This parameter is valid only for symmetric encryption KMS keys in a single Region. You cannot create any other type of KMS key in a custom key store.

When you create a KMS key in an CloudHSM key store, KMS generates a non-exportable 256-bit symmetric key in its associated CloudHSM cluster and associates it with the KMS key. When you create a KMS key in an external key store, you must use the XksKeyId parameter to specify an external key that serves as key material for the KMS key.

customer_master_key_spec class-attribute instance-attribute 
customer_master_key_spec: str | None = ...

Instead, use the KeySpec parameter.

The KeySpec and CustomerMasterKeySpec parameters work the same way. Only the names differ. We recommend that you use KeySpec parameter in your code. However, to avoid breaking changes, KMS supports both parameters.

description class-attribute instance-attribute 
description: str | None = ...

A description of the KMS key. Use a description that helps you decide whether the KMS key is appropriate for a task. The default value is an empty string (no description).

Warning

Do not include confidential or sensitive information in this field. This field may be displayed in plaintext in CloudTrail logs and other output.

To set or change the description after the key is created, use UpdateKeyDescription.

key_spec class-attribute instance-attribute 
key_spec: str | None = ...

Specifies the type of KMS key to create. The default value, SYMMETRIC_DEFAULT, creates a KMS key with a 256-bit AES-GCM key that is used for encryption and decryption, except in China Regions, where it creates a 128-bit symmetric key that uses SM4 encryption. For a detailed description of all supported key specs, see Key spec reference in the Key Management Service Developer Guide .

The KeySpec determines whether the KMS key contains a symmetric key or an asymmetric key pair. It also determines the algorithms that the KMS key supports. You can't change the KeySpec after the KMS key is created. To further restrict the algorithms that can be used with the KMS key, use a condition key in its key policy or IAM policy. For more information, see kms:EncryptionAlgorithm, kms:MacAlgorithm, kms:KeyAgreementAlgorithm, or kms:SigningAlgorithm in the Key Management Service Developer Guide .

Warning

Amazon Web Services services that are integrated with KMS use symmetric encryption KMS keys to protect your data. These services do not support asymmetric KMS keys or HMAC KMS keys.

KMS supports the following key specs for KMS keys:

  • Symmetric encryption key (default)

  • SYMMETRIC_DEFAULT

  • HMAC keys (symmetric)

  • HMAC_224

  • HMAC_256

  • HMAC_384

  • HMAC_512

  • Asymmetric RSA key pairs (encryption and decryption -or- signing and verification)

  • RSA_2048

  • RSA_3072

  • RSA_4096

  • Asymmetric NIST-standard elliptic curve key pairs (signing and verification -or- deriving shared secrets)

  • ECC_NIST_P256 (secp256r1)

  • ECC_NIST_P384 (secp384r1)

  • ECC_NIST_P521 (secp521r1)

  • ECC_NIST_EDWARDS25519 (ed25519) - signing and verification only

    • Note: For ECC_NIST_EDWARDS25519 KMS keys, the ED25519_SHA_512 signing algorithm requires MessageType:RAW , while ED25519_PH_SHA_512 requires MessageType:DIGEST . These message types cannot be used interchangeably.

  • Other asymmetric elliptic curve key pairs (signing and verification)

  • ECC_SECG_P256K1 (secp256k1), commonly used for cryptocurrencies.

  • Asymmetric ML-DSA key pairs (signing and verification)

  • ML_DSA_44

  • ML_DSA_65

  • ML_DSA_87

  • Asymmetric ML-KEM key pairs (establishing shared secrets)

  • ML_KEM_512

  • ML_KEM_768

  • ML_KEM_1024

The ML-KEM key specs are not available in China Regions.

  • SM2 key pairs (encryption and decryption -or- signing and verification -or- deriving shared secrets)

  • SM2 (China Regions only)

key_usage class-attribute instance-attribute 
key_usage: str | None = ...

Determines the cryptographic operations for which you can use the KMS key. The default value is ENCRYPT_DECRYPT. This parameter is optional when you are creating a symmetric encryption KMS key; otherwise, it is required. You can't change the KeyUsage value after the KMS key is created. Each KMS key can have only one key usage. This follows key usage best practices according to NIST SP 800-57 Recommendations for Key Management, section 5.2, Key usage.

Select only one valid value.

  • For symmetric encryption KMS keys, omit the parameter or specify ENCRYPT_DECRYPT.

  • For HMAC KMS keys (symmetric), specify GENERATE_VERIFY_MAC.

  • For asymmetric KMS keys with RSA key pairs, specify ENCRYPT_DECRYPT or SIGN_VERIFY.

  • For asymmetric KMS keys with NIST-standard elliptic curve key pairs, specify SIGN_VERIFY or KEY_AGREEMENT.

  • For asymmetric KMS keys with ECC_SECG_P256K1 key pairs, specify SIGN_VERIFY.

  • For asymmetric KMS keys with ML-DSA key pairs, specify SIGN_VERIFY.

  • For asymmetric KMS keys with ML-KEM key pairs, specify ENCAPSULATE_DECAPSULATE.

  • For asymmetric KMS keys with SM2 key pairs (China Regions only), specify ENCRYPT_DECRYPT, SIGN_VERIFY, or KEY_AGREEMENT.

multi_region class-attribute instance-attribute 
multi_region: bool | None = ...

Creates a multi-Region primary key that you can replicate into other Amazon Web Services Regions. You cannot change this value after you create the KMS key.

For a multi-Region key, set this parameter to True. For a single-Region KMS key, omit this parameter or set it to False. The default value is False.

This operation supports multi-Region keys, an KMS feature that lets you create multiple interoperable KMS keys in different Amazon Web Services Regions. Because these KMS keys have the same key ID, key material, and other metadata, you can use them interchangeably to encrypt data in one Amazon Web Services Region and decrypt it in a different Amazon Web Services Region without re-encrypting the data or making a cross-Region call. For more information about multi-Region keys, see Multi-Region keys in KMS in the Key Management Service Developer Guide.

This value creates a primary key, not a replica. To create a replica key, use the ReplicateKey operation.

You can create a symmetric or asymmetric multi-Region key, and you can create a multi-Region key with imported key material. However, you cannot create a multi-Region key in a custom key store.

origin class-attribute instance-attribute 
origin: str | None = ...

The source of the key material for the KMS key. You cannot change the origin after you create the KMS key. The default is AWS_KMS, which means that KMS creates the key material.

To create a KMS key with no key material (for imported key material), set this value to EXTERNAL. For more information about importing key material into KMS, see Importing Key Material in the Key Management Service Developer Guide. The EXTERNAL origin value is valid only for symmetric KMS keys.

To create a KMS key in an CloudHSM key store and create its key material in the associated CloudHSM cluster, set this value to AWS_CLOUDHSM. You must also use the CustomKeyStoreId parameter to identify the CloudHSM key store. The KeySpec value must be SYMMETRIC_DEFAULT.

To create a KMS key in an external key store, set this value to EXTERNAL_KEY_STORE. You must also use the CustomKeyStoreId parameter to identify the external key store and the XksKeyId parameter to identify the associated external key. The KeySpec value must be SYMMETRIC_DEFAULT.

policy class-attribute instance-attribute 
policy: str | None = ...

The key policy to attach to the KMS key.

If you provide a key policy, it must meet the following criteria:

  • The key policy must allow the calling principal to make a subsequent PutKeyPolicy request on the KMS key. This reduces the risk that the KMS key becomes unmanageable. For more information, see Default key policy in the Key Management Service Developer Guide. (To omit this condition, set BypassPolicyLockoutSafetyCheck to true.)

  • Each statement in the key policy must contain one or more principals. The principals in the key policy must exist and be visible to KMS. When you create a new Amazon Web Services principal, you might need to enforce a delay before including the new principal in a key policy because the new principal might not be immediately visible to KMS. For more information, see Changes that I make are not always immediately visible in the Amazon Web Services Identity and Access Management User Guide.

Note

If either of the required Resource or Action elements are missing from a key policy statement, the policy statement has no effect. When a key policy statement is missing one of these elements, the KMS console correctly reports an error, but the CreateKey and PutKeyPolicy API requests succeed, even though the policy statement is ineffective.

For more information on required key policy elements, see Elements in a key policy in the Key Management Service Developer Guide.

If you do not provide a key policy, KMS attaches a default key policy to the KMS key. For more information, see Default key policy in the Key Management Service Developer Guide.

Note

If the key policy exceeds the length constraint, KMS returns a LimitExceededException.

For help writing and formatting a JSON policy document, see the IAM JSON Policy Reference in the Identity and Access Management User Guide .

tags class-attribute instance-attribute 
tags: list[Tag] | None = ...

Assigns one or more tags to the KMS key. Use this parameter to tag the KMS key when it is created. To tag an existing KMS key, use the TagResource operation.

Warning

Do not include confidential or sensitive information in this field. This field may be displayed in plaintext in CloudTrail logs and other output.

Note: Tagging or untagging a KMS key can allow or deny permission to the KMS key. For details, see ABAC for KMS in the Key Management Service Developer Guide.

To use this parameter, you must have kms:TagResource permission in an IAM policy.

Each tag consists of a tag key and a tag value. Both the tag key and the tag value are required, but the tag value can be an empty (null) string. You cannot have more than one tag on a KMS key with the same tag key. If you specify an existing tag key with a different tag value, KMS replaces the current tag value with the specified one.

When you add tags to an Amazon Web Services resource, Amazon Web Services 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 details, see Tags in KMS.

xks_key_id class-attribute instance-attribute 
xks_key_id: str | None = ...

Identifies the external key that serves as key material for the KMS key in an external key store. Specify the ID that the external key store proxy uses to refer to the external key. For help, see the documentation for your external key store proxy.

This parameter is required for a KMS key with an Origin value of EXTERNAL_KEY_STORE. It is not valid for KMS keys with any other Origin value.

The external key must be an existing 256-bit AES symmetric encryption key hosted outside of Amazon Web Services in an external key manager associated with the external key store specified by the CustomKeyStoreId parameter. This key must be enabled and configured to perform encryption and decryption. Each KMS key in an external key store must use a different external key. For details, see Requirements for a KMS key in an external key store in the Key Management Service Developer Guide.

Each KMS key in an external key store is associated two backing keys. One is key material that KMS generates. The other is the external key specified by this parameter. When you use the KMS key in an external key store to encrypt data, the encryption operation is performed first by KMS using the KMS key material, and then by the external key manager using the specified external key, a process known as double encryption. For details, see Double encryption in the Key Management Service Developer Guide.

Output

CreateKeyOutput dataclass

Bases: _SerdeShape

Dataclass for CreateKeyOutput structure.

Attributes

key_metadata class-attribute instance-attribute 
key_metadata: KeyMetadata | None = ...

Metadata associated with the KMS key.

response_metadata class-attribute instance-attribute 
response_metadata: ResponseMetadata = ...

Metadata about the response that produced this output. Use this to recover the request identifiers a service's support team needs in order to investigate a call. Members of the metadata are individually optional.