Decrypts ciphertext and then reencrypts it entirely within AWS KMS. You can use this operation to change the customer master key (CMK) under which data is encrypted, such as when you manually rotate a CMK or change the CMK that protects a ciphertext. You can also use it to reencrypt ciphertext under the same CMK, such as to change the encryption context of a ciphertext.
kms_re_encrypt(CiphertextBlob, SourceEncryptionContext, SourceKeyId,
DestinationKeyId, DestinationEncryptionContext,
SourceEncryptionAlgorithm, DestinationEncryptionAlgorithm, GrantTokens)[required] Ciphertext of the data to reencrypt.
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 represents 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 optional when encrypting with a symmetric CMK, but it is highly recommended.
For more information, see Encryption Context in the AWS Key Management Service Developer Guide.
A unique identifier for the CMK that is used to decrypt the ciphertext before it reencrypts it using the destination CMK.
This parameter is required only when the ciphertext was encrypted under an asymmetric CMK. Otherwise, AWS KMS uses the metadata that it adds to the ciphertext blob to determine which CMK was used to encrypt the ciphertext. However, you can use this parameter to ensure that a particular CMK (of any kind) is used to decrypt the ciphertext before it is reencrypted.
If you specify a KeyId value, the decrypt part of the ReEncrypt
operation succeeds only if the specified CMK was used to encrypt the
ciphertext.
To specify a CMK, use its key ID, Amazon Resource Name (ARN), alias
name, or alias ARN. When using an alias name, prefix it with "alias/".
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 CMK, use ListKeys or DescribeKey. To get the alias name and alias ARN, use ListAliases.
[required] A unique identifier for the CMK that is used to reencrypt the data.
Specify a symmetric or asymmetric CMK with a KeyUsage value of
ENCRYPT_DECRYPT. To find the KeyUsage value of a CMK, use the
DescribeKey operation.
To specify a CMK, use its key ID, Amazon Resource Name (ARN), alias
name, or alias ARN. When using an alias name, prefix it with "alias/".
To specify a CMK in a different AWS 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 CMK, use ListKeys or DescribeKey. To get the alias name and alias ARN, use ListAliases.
Specifies that encryption context to use when the reencrypting the data.
A destination encryption context is valid only when the destination CMK is a symmetric CMK. The standard ciphertext format for asymmetric CMKs does not include fields for metadata.
An encryption context is a collection of non-secret key-value pairs that represents 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 optional when encrypting with a symmetric CMK, but it is highly recommended.
For more information, see Encryption Context in the AWS Key Management Service Developer Guide.
Specifies the encryption algorithm that AWS KMS will use to decrypt the
ciphertext before it is reencrypted. The default value,
SYMMETRIC_DEFAULT, represents the algorithm used for symmetric CMKs.
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 CMK.
Specifies the encryption algorithm that AWS KMS will use to reecrypt the
data after it has decrypted it. The default value, SYMMETRIC_DEFAULT,
represents the encryption algorithm used for symmetric CMKs.
This parameter is required only when the destination CMK is an asymmetric CMK.
A list of grant tokens.
For more information, see Grant Tokens in the AWS Key Management Service Developer Guide.
svc$re_encrypt(
CiphertextBlob = raw,
SourceEncryptionContext = list(
"string"
),
SourceKeyId = "string",
DestinationKeyId = "string",
DestinationEncryptionContext = list(
"string"
),
SourceEncryptionAlgorithm = "SYMMETRIC_DEFAULT"|"RSAES_OAEP_SHA_1"|"RSAES_OAEP_SHA_256",
DestinationEncryptionAlgorithm = "SYMMETRIC_DEFAULT"|"RSAES_OAEP_SHA_1"|"RSAES_OAEP_SHA_256",
GrantTokens = list(
"string"
)
)
The ReEncrypt operation can decrypt ciphertext that was encrypted by
using an AWS KMS CMK in an AWS KMS operation, such as Encrypt or
GenerateDataKey. It can also decrypt ciphertext that was encrypted by
using the public key of an asymmetric CMK outside of AWS KMS. However,
it cannot decrypt ciphertext produced by other libraries, such as the
AWS Encryption SDK
or Amazon S3 client-side encryption.
These libraries return a ciphertext format that is incompatible with AWS
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 CMK, you must identify the source CMK, that is, the CMK that encrypted the ciphertext. You must also supply the encryption algorithm that was used. This information is required to decrypt the data.
It is optional, but you can specify a source CMK even when the
ciphertext was encrypted under a symmetric CMK. This ensures that
the ciphertext is decrypted only by using a particular CMK. If the
CMK that you specify cannot decrypt the ciphertext, the ReEncrypt
operation fails.
To reencrypt the data, you must specify the destination CMK, that is, the CMK that re-encrypts the data after it is decrypted. You can select a symmetric or asymmetric CMK. If the destination CMK is an asymmetric CMK, you must also provide the encryption algorithm. The algorithm that you choose must be compatible with the CMK.
When you use an asymmetric CMK to encrypt or reencrypt data, be sure to record the CMK and encryption algorithm that you choose. You will be required to provide the same CMK and encryption algorithm when you decrypt the data. If the CMK and algorithm do not match the values used to encrypt the data, the decrypt operation fails.
You are not required to supply the CMK ID and encryption algorithm when you decrypt with symmetric CMKs because AWS KMS stores this information in the ciphertext blob. AWS KMS cannot store metadata in ciphertext generated with asymmetric keys. The standard format for asymmetric key ciphertext does not include configurable fields.
Unlike other AWS KMS API operations, ReEncrypt callers must have two
permissions:
kms:EncryptFrom permission on the source CMK
kms:EncryptTo permission on the destination CMK
To permit reencryption from
or to a CMK, 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 CMK. But you must include it manually when you
create a CMK programmatically or when you use the PutKeyPolicy operation
set a key policy.
The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.
# NOT RUN {
# The following example reencrypts data with the specified CMK.
svc$re_encrypt(
CiphertextBlob = "<binary data>",
DestinationKeyId = "0987dcba-09fe-87dc-65ba-ab0987654321"
)
# }
# NOT RUN {
# }
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