re_encrypt¶
Operation¶
async
¶
re_encrypt(input: ReEncryptInput, plugins: list[Plugin] | None = None) -> ReEncryptOutput
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.
Warning: 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.
Note
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:
-
Decrypt
-
Encrypt
-
GenerateDataKey
-
GenerateDataKeyPair
Eventual consistency: The KMS API follows an eventual consistency model. For more information, see KMS eventual consistency.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
input
|
ReEncryptInput
|
An instance of |
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 |
|---|---|
ReEncryptOutput
|
An instance of |
Input¶
dataclass
¶
Bases: _SerdeShape
Dataclass for ReEncryptInput structure.
Attributes¶
class-attribute
instance-attribute
¶
ciphertext_blob: bytes | None = ...
Ciphertext of the data to reencrypt.
This parameter is required in all cases except when DryRun is true
and DryRunModifiers is set to IGNORE_CIPHERTEXT.
class-attribute
instance-attribute
¶
destination_encryption_algorithm: str | 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.
class-attribute
instance-attribute
¶
Specifies that encryption context to use when the reencrypting the data.
Warning
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.
class-attribute
instance-attribute
¶
destination_key_id: str | None = ...
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
KeyUsage value of ENCRYPT_DECRYPT. To find the KeyUsage value 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.
class-attribute
instance-attribute
¶
dry_run: bool | None = ...
Checks if your request will succeed. DryRun is an optional parameter.
To learn more about how to use this parameter, see Testing your permissions in the Key Management Service Developer Guide.
class-attribute
instance-attribute
¶
Specifies the modifiers to apply to the dry run operation.
DryRunModifiers is an optional parameter that only applies when
DryRun is set to true.
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.
class-attribute
instance-attribute
¶
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.
class-attribute
instance-attribute
¶
source_encryption_algorithm: str | 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.
class-attribute
instance-attribute
¶
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.
class-attribute
instance-attribute
¶
source_key_id: str | 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 ReEncrypt operation throws an
IncorrectKeyException.
This parameter is required only when the ciphertext was encrypted under
an asymmetric KMS key or when DryRun is true and DryRunModifiers
is set to IGNORE_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.
Output¶
dataclass
¶
Bases: _SerdeShape
Dataclass for ReEncryptOutput structure.
Attributes¶
class-attribute
instance-attribute
¶
ciphertext_blob: bytes | None = ...
The reencrypted data. When you use the HTTP API or the Amazon Web Services CLI, the value is Base64-encoded. Otherwise, it is not Base64-encoded.
class-attribute
instance-attribute
¶
destination_encryption_algorithm: str | None = ...
The encryption algorithm that was used to reencrypt the data.
class-attribute
instance-attribute
¶
destination_key_material_id: str | None = ...
The identifier of the key material used to reencrypt the data. This field is present only when data is reencrypted using a symmetric encryption KMS key.
class-attribute
instance-attribute
¶
key_id: str | None = ...
The Amazon Resource Name (key ARN) of the KMS key that was used to reencrypt the data.
class-attribute
instance-attribute
¶
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.
class-attribute
instance-attribute
¶
source_encryption_algorithm: str | None = ...
The encryption algorithm that was used to decrypt the ciphertext before it was reencrypted.