re_encrypt
async
¶
re_encrypt(
destination_key_id: KeyIdType,
*,
config_overrides: Optional[AsyncKMSClientConfig] = None,
ciphertext_blob: Optional[CiphertextType] = None,
source_encryption_context: Optional[EncryptionContextType] = None,
source_key_id: Optional[KeyIdType] = None,
destination_encryption_context: Optional[EncryptionContextType] = None,
source_encryption_algorithm: Optional[EncryptionAlgorithmSpec] = None,
destination_encryption_algorithm: Optional[EncryptionAlgorithmSpec] = None,
grant_tokens: Optional[GrantTokenList] = None,
dry_run: Optional[NullableBooleanType] = None,
dry_run_modifiers: Optional[DryRunModifierList] = None,
) -> ReEncryptResponse
Decrypts ciphertext and then reencrypts it entirely within KMS. You can use this operation to change the KMS key under which data is encrypted, such as when you manually rotate a KMS key or change the KMS key that protects a ciphertext. You can also use it to reencrypt ciphertext under the same KMS key, such as to change the encryption context of a ciphertext.
The ReEncrypt operation can decrypt ciphertext that was encrypted by using a KMS key in an KMS operation, such as Encrypt or GenerateDataKey. It can also decrypt ciphertext that was encrypted by using the public key of an asymmetric KMS key outside of KMS. However, it cannot decrypt ciphertext produced by other libraries, such as the Amazon Web Services Encryption SDK or Amazon S3 client-side encryption. These libraries return a ciphertext format that is incompatible with KMS.
When you use the ReEncrypt operation, you need to provide information for the decrypt operation and the subsequent encrypt operation.
-
If your ciphertext was encrypted under an asymmetric KMS key, you must use the
SourceKeyIdparameter to identify the KMS key that encrypted the ciphertext. You must also supply the encryption algorithm that was used. This information is required to decrypt the data. -
If your ciphertext was encrypted under a symmetric encryption KMS key, the
SourceKeyIdparameter is optional. KMS can get this information from metadata that it adds to the symmetric ciphertext blob. This feature adds durability to your implementation by ensuring that authorized users can decrypt ciphertext decades after it was encrypted, even if they've lost track of the key ID. However, specifying the source KMS key is always recommended as a best practice. When you use theSourceKeyIdparameter to specify a KMS key, KMS uses only the KMS key you specify. If the ciphertext was encrypted under a different KMS key, theReEncryptoperation fails. This practice ensures that you use the KMS key that you intend. -
To reencrypt the data, you must use the
DestinationKeyIdparameter to specify the KMS key that re-encrypts the data after it is decrypted. If the destination KMS key is an asymmetric KMS key, you must also provide the encryption algorithm. The algorithm that you choose must be compatible with the KMS key.When you use an asymmetric KMS key to encrypt or reencrypt data, be sure to record the KMS key and encryption algorithm that you choose. You will be required to provide the same KMS key and encryption algorithm when you decrypt the data. If the KMS key and algorithm do not match the values used to encrypt the data, the decrypt operation fails.
You are not required to supply the key ID and encryption algorithm when you decrypt with symmetric encryption KMS keys because KMS stores this information in the ciphertext blob. KMS cannot store metadata in ciphertext generated with asymmetric keys. The standard format for asymmetric key ciphertext does not include configurable fields.
The KMS key that you use for this operation must be in a compatible key state. For details, see Key states of KMS keys in the Key Management Service Developer Guide.
When using grants with SourceArn constraints for ReEncrypt operations, the grants on both the source KMS key (for ReEncryptFrom) and the destination KMS key (for ReEncryptTo) must specify the same SourceArn value.
Cross-account use: Yes. The source KMS key and destination KMS key can be in different Amazon Web Services accounts. Either or both KMS keys can be in a different account than the caller. To specify a KMS key in a different account, use the key ARN or alias ARN. A short key ID is also acceptable for the source key when decrypting symmetric ciphertexts, though using a full key ARN is recommended to be more explicit about the intended KMS key.
Required permissions:
-
kms:ReEncryptFrom permission on the source KMS key (key policy)
-
kms:ReEncryptTo permission on the destination KMS key (key policy)
To permit reencryption from or to a KMS key, include the "kms:ReEncrypt*" permission in your key policy. This permission is automatically included in the key policy when you use the console to create a KMS key. But you must include it manually when you create a KMS key programmatically or when you use the PutKeyPolicy operation to set a key policy.
Related operations:
Eventual consistency: The KMS API follows an eventual consistency model. For more information, see KMS eventual consistency.
Parameters:
-
ciphertext_blob(Optional[CiphertextType], default:None) –Ciphertext of the data to reencrypt.
This parameter is required in all cases except when
DryRunistrueandDryRunModifiersis set toIGNORE_CIPHERTEXT. -
source_encryption_context(Optional[EncryptionContextType], default:None) –Specifies the encryption context to use to decrypt the ciphertext. Enter the same encryption context that was used to encrypt the ciphertext.
An encryption context is a collection of non-secret key-value pairs that represent additional authenticated data. When you use an encryption context to encrypt data, you must specify the same (an exact case-sensitive match) encryption context to decrypt the data. An encryption context is supported only on operations with symmetric encryption KMS keys. On operations with symmetric encryption KMS keys, an encryption context is optional, but it is strongly recommended.
For more information, see Encryption context in the Key Management Service Developer Guide.
-
source_key_id(Optional[KeyIdType], default:None) –Specifies the KMS key that KMS will use to decrypt the ciphertext before it is re-encrypted.
Enter a key ID of the KMS key that was used to encrypt the ciphertext. If you identify a different KMS key, the
ReEncryptoperation throws anIncorrectKeyException.This parameter is required only when the ciphertext was encrypted under an asymmetric KMS key or when
DryRunistrueandDryRunModifiersis set toIGNORE_CIPHERTEXT. If you used a symmetric encryption KMS key, KMS can get the KMS key from metadata that it adds to the symmetric ciphertext blob. However, it is always recommended as a best practice. This practice ensures that you use the KMS key that you intend.To specify a KMS key, use its key ID, key ARN, alias name, or alias ARN. When using an alias name, prefix it with
"alias/". To specify a KMS key in a different Amazon Web Services account, you should use the key ARN or alias ARN.For example:
-
Key ID:
1234abcd-12ab-34cd-56ef-1234567890ab -
Key ARN:
arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab -
Alias name:
alias/ExampleAlias -
Alias ARN:
arn:aws:kms:us-east-2:111122223333:alias/ExampleAlias
To get the key ID and key ARN for a KMS key, use ListKeys or DescribeKey. To get the alias name and alias ARN, use ListAliases.
-
-
destination_key_id(KeyIdType) –A unique identifier for the KMS key that is used to reencrypt the data. Specify a symmetric encryption KMS key or an asymmetric KMS key with a
KeyUsagevalue ofENCRYPT_DECRYPT. To find theKeyUsagevalue of a KMS key, use the DescribeKey operation.To specify a KMS key, use its key ID, key ARN, alias name, or alias ARN. When using an alias name, prefix it with
"alias/". To specify a KMS key in a different Amazon Web Services account, you must use the key ARN or alias ARN.For example:
-
Key ID:
1234abcd-12ab-34cd-56ef-1234567890ab -
Key ARN:
arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab -
Alias name:
alias/ExampleAlias -
Alias ARN:
arn:aws:kms:us-east-2:111122223333:alias/ExampleAlias
To get the key ID and key ARN for a KMS key, use ListKeys or DescribeKey. To get the alias name and alias ARN, use ListAliases.
-
-
destination_encryption_context(Optional[EncryptionContextType], default:None) –Specifies that encryption context to use when the reencrypting the data.
Do not include confidential or sensitive information in this field. This field may be displayed in plaintext in CloudTrail logs and other output.
A destination encryption context is valid only when the destination KMS key is a symmetric encryption KMS key. The standard ciphertext format for asymmetric KMS keys does not include fields for metadata.
An encryption context is a collection of non-secret key-value pairs that represent additional authenticated data. When you use an encryption context to encrypt data, you must specify the same (an exact case-sensitive match) encryption context to decrypt the data. An encryption context is supported only on operations with symmetric encryption KMS keys. On operations with symmetric encryption KMS keys, an encryption context is optional, but it is strongly recommended.
For more information, see Encryption context in the Key Management Service Developer Guide.
-
source_encryption_algorithm(Optional[EncryptionAlgorithmSpec], default:None) –Specifies the encryption algorithm that KMS will use to decrypt the ciphertext before it is reencrypted. The default value,
SYMMETRIC_DEFAULT, represents the algorithm used for symmetric encryption KMS keys.Specify the same algorithm that was used to encrypt the ciphertext. If you specify a different algorithm, the decrypt attempt fails.
This parameter is required only when the ciphertext was encrypted under an asymmetric KMS key.
-
destination_encryption_algorithm(Optional[EncryptionAlgorithmSpec], default:None) –Specifies the encryption algorithm that KMS will use to reecrypt the data after it has decrypted it. The default value,
SYMMETRIC_DEFAULT, represents the encryption algorithm used for symmetric encryption KMS keys.This parameter is required only when the destination KMS key is an asymmetric KMS key.
-
grant_tokens(Optional[GrantTokenList], default:None) –A list of grant tokens.
Use a grant token when your permission to call this operation comes from a new grant that has not yet achieved eventual consistency. For more information, see Grant token and Using a grant token in the Key Management Service Developer Guide.
-
dry_run(Optional[NullableBooleanType], default:None) –Checks if your request will succeed.
DryRunis an optional parameter.To learn more about how to use this parameter, see Testing your permissions in the Key Management Service Developer Guide.
-
dry_run_modifiers(Optional[DryRunModifierList], default:None) –Specifies the modifiers to apply to the dry run operation.
DryRunModifiersis an optional parameter that only applies whenDryRunis set totrue.When set to
IGNORE_CIPHERTEXT, KMS performs only authorization validation without ciphertext validation. This allows you to test permissions without requiring a valid ciphertext blob.To learn more about how to use this parameter, see Testing your permissions in the Key Management Service Developer Guide.
Raises:
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DependencyTimeoutException–The system timed out while trying to fulfill the request. You can retry the request.
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DisabledException–The request was rejected because the specified KMS key is not enabled.
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DryRunOperationException–The request was rejected because the DryRun parameter was specified.
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IncorrectKeyException– -
InvalidCiphertextException–From the Decrypt or ReEncrypt operation, the request was rejected because the specified ciphertext, or additional authenticated data incorporated into the ciphertext, such as the encryption context, is corrupted, missing, or otherwise invalid.
From the ImportKeyMaterial operation, the request was rejected because KMS could not decrypt the encrypted (wrapped) key material.
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InvalidGrantTokenException–The request was rejected because the specified grant token is not valid.
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InvalidKeyUsageException–The request was rejected for one of the following reasons:
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The
KeyUsagevalue of the KMS key is incompatible with the API operation. -
The encryption algorithm or signing algorithm specified for the operation is incompatible with the type of key material in the KMS key
(KeySpec).
For encrypting, decrypting, re-encrypting, and generating data keys, the
KeyUsagemust beENCRYPT_DECRYPT. For signing and verifying messages, theKeyUsagemust beSIGN_VERIFY. For generating and verifying message authentication codes (MACs), theKeyUsagemust beGENERATE_VERIFY_MAC. For deriving key agreement secrets, theKeyUsagemust beKEY_AGREEMENT. To find theKeyUsageof a KMS key, use the DescribeKey operation.To find the encryption or signing algorithms supported for a particular KMS key, use the DescribeKey operation.
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KeyUnavailableException–The request was rejected because the specified KMS key was not available. You can retry the request.
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KMSInternalException–The request was rejected because an internal exception occurred. The request can be retried.
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KMSInvalidStateException–The request was rejected because the state of the specified resource is not valid for this request.
This exceptions means one of the following:
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The key state of the KMS key is not compatible with the operation.
To find the key state, use the DescribeKey operation. For more information about which key states are compatible with each KMS operation, see Key states of KMS keys in the Key Management Service Developer Guide .
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For cryptographic operations on KMS keys in custom key stores, this exception represents a general failure with many possible causes. To identify the cause, see the error message that accompanies the exception.
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NotFoundException–The request was rejected because the specified entity or resource could not be found.
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UnknownServiceError–The service returned an error code this client does not model.
Examples:
To reencrypt data The following example reencrypts data with the specified KMS key.
>>> await client.re_encrypt(ciphertext_blob='<binary data>', destination_key_id='0987dcba-09fe-87dc-65ba-ab0987654321')
Source code in docs_src/capo_kms/_services/async_kms.py
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