Use GenerateDataKey with an Amazon SDK or CLI

Example 1: To generate a 256-bit symmetric data key

The following generate-data-key example requests a 256-bit symmetric data key for use outside of Amazon. The command returns a plaintext data key for immediate use and deletion, and a copy of that data key encrypted under the specified KMS key. You can safely store the encrypted data key with the encrypted data.

To request a 256-bit data key, use the key-spec parameter with a value of AES_256. To request a 128-bit data key, use the key-spec parameter with a value of AES_128. For all other data key lengths, use the number-of-bytes parameter.

The KMS key you specify must be a symmetric encryption KMS key, that is, a KMS key with a key spec value of SYMMETRIC_DEFAULT.

aws kms generate-data-key \
    --key-id alias/ExampleAlias \
    --key-spec AES_256

Output:

{
    "Plaintext": "VdzKNHGzUAzJeRBVY+uUmofUGGiDzyB3+i9fVkh3piw=",
    "KeyId": "arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab",
    "CiphertextBlob": "AQEDAHjRYf5WytIc0C857tFSnBaPn2F8DgfmThbJlGfR8P3WlwAAAH4wfAYJKoZIhvcNAQcGoG8wbQIBADBoBgkqhkiG9w0BBwEwHgYJYIZIAWUDBAEuMBEEDEFogLqPWZconQhwHAIBEIA7d9AC7GeJJM34njQvg4Wf1d5sw0NIo1MrBqZa+YdhV8MrkBQPeac0ReRVNDt9qleAt+SHgIRF8P0H+7U="
}

The Plaintext (plaintext data key) and the CiphertextBlob (encrypted data key) are returned in base64-encoded format.

For more information, see Data keys <https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#data-keys in the Amazon Key Management Service Developer Guide.

Example 2: To generate a 512-bit symmetric data key

The following generate-data-key example requests a 512-bit symmetric data key for encryption and decryption. The command returns a plaintext data key for immediate use and deletion, and a copy of that data key encrypted under the specified KMS key. You can safely store the encrypted data key with the encrypted data.

To request a key length other than 128 or 256 bits, use the number-of-bytes parameter. To request a 512-bit data key, the following example uses the number-of-bytes parameter with a value of 64 (bytes).

The KMS key you specify must be a symmetric encryption KMS key, that is, a KMS key with a key spec value of SYMMETRIC_DEFAULT.

NOTE: The values in the output of this example are truncated for display.

aws kms generate-data-key \
    --key-id 1234abcd-12ab-34cd-56ef-1234567890ab \
    --number-of-bytes 64

Output:

{
    "CiphertextBlob": "AQIBAHi6LtupRpdKl2aJTzkK6FbhOtQkMlQJJH3PdtHvS/y+hAEnX/QQNmMwDfg2korNMEc8AAACaDCCAmQGCSqGSIb3DQEHBqCCAlUwggJRAgEAMIICSgYJKoZ...",
    "Plaintext": "ty8Lr0Bk6OF07M2BWt6qbFdNB+G00ZLtf5MSEb4al3R2UKWGOp06njAwy2n72VRm2m7z/Pm9Wpbvttz6a4lSo9hgPvKhZ5y6RTm4OovEXiVfBveyX3DQxDzRSwbKDPk/...",
    "KeyId": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab"
}

The Plaintext (plaintext data key) and CiphertextBlob (encrypted data key) are returned in base64-encoded format.

For more information, see Data keys <https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#data-keys in the Amazon Key Management Service Developer Guide.

class KeyManager:
    def __init__(self, kms_client):
        self.kms_client = kms_client
        self.created_keys = []


    def generate_data_key(self, key_id):
        """
        Generates a symmetric data key that can be used for client-side encryption.
        """
        answer = input(
            f"Do you want to generate a symmetric data key from key {key_id} (y/n)? "
        )
        if answer.lower() == "y":
            try:
                data_key = self.kms_client.generate_data_key(
                    KeyId=key_id, KeySpec="AES_256"
                )
            except ClientError as err:
                logger.error(
                    "Couldn't generate a data key for key %s. Here's why: %s",
                    key_id,
                    err.response["Error"]["Message"],
                )
            else:
                pprint(data_key)

async fn make_key(client: &Client, key: &str) -> Result<(), Error> {
    let resp = client
        .generate_data_key()
        .key_id(key)
        .key_spec(DataKeySpec::Aes256)
        .send()
        .await?;

    // Did we get an encrypted blob?
    let blob = resp.ciphertext_blob.expect("Could not get encrypted text");
    let bytes = blob.as_ref();

    let s = base64::encode(bytes);

    println!();
    println!("Data key:");
    println!("{}", s);

    Ok(())
}