Container for the parameters to the GenerateDataKey operation. Returns a data encryption key that you can use in your application to encrypt data locally.
You must specify the customer master key (CMK) under which to generate the data key. You must also specify the length of the data key using either the KeySpec or NumberOfBytes field. You must specify one field or the other, but not both. For common key lengths (128-bit and 256-bit symmetric keys), we recommend that you use KeySpec.
This operation returns a plaintext copy of the data key in the Plaintext field of the response, and an encrypted copy of the data key in the CiphertextBlob field. The data key is encrypted under the CMK specified in the KeyId field of the request.
We recommend that you use the following pattern to encrypt data locally in your application:
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Use this operation (GenerateDataKey) to retrieve a data encryption key.
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Use the plaintext data encryption key (returned in the Plaintext field of the response) to encrypt data locally, then erase the plaintext data key from memory.
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Store the encrypted data key (returned in the CiphertextBlob field of the response) alongside the locally encrypted data.
To decrypt data locally:
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Use the Decrypt operation to decrypt the encrypted data key into a plaintext copy of the data key.
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Use the plaintext data key to decrypt data locally, then erase the plaintext data key from memory.
To return only an encrypted copy of the data key, use GenerateDataKeyWithoutPlaintext. To return an arbitrary unpredictable byte string, use GenerateRandom.
If you use the optional EncryptionContext field, you must store at least enough information to be able to reconstruct the full encryption context when you later send the ciphertext to the Decrypt operation. It is a good practice to choose an encryption context that you can reconstruct on the fly to better secure the ciphertext. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.
