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User Guide

First time using the AWS CLI? See the User Guide for help getting started.

[ aws . kms ]



Returns a data encryption key encrypted under a customer master key (CMK). This operation is identical to GenerateDataKey but returns only the encrypted copy of the data key.

To perform this operation on a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

This operation is useful in a system that has multiple components with different degrees of trust. For example, consider a system that stores encrypted data in containers. Each container stores the encrypted data and an encrypted copy of the data key. One component of the system, called the control plane , creates new containers. When it creates a new container, it uses this operation (GenerateDataKeyWithoutPlaintext ) to get an encrypted data key and then stores it in the container. Later, a different component of the system, called the data plane , puts encrypted data into the containers. To do this, it passes the encrypted data key to the Decrypt operation, then uses the returned plaintext data key to encrypt data, and finally stores the encrypted data in the container. In this system, the control plane never sees the plaintext data key.

The result of this operation varies with the key state of the CMK. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide .

See also: AWS API Documentation

See 'aws help' for descriptions of global parameters.


--key-id <value>
[--encryption-context <value>]
[--key-spec <value>]
[--number-of-bytes <value>]
[--grant-tokens <value>]
[--cli-input-json <value>]
[--generate-cli-skeleton <value>]


--key-id (string)

The identifier of the customer master key (CMK) under which to generate and encrypt the data encryption key.

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 .

--encryption-context (map)

A set of key-value pairs that represents additional authenticated data.

For more information, see Encryption Context in the AWS Key Management Service Developer Guide .

Shorthand Syntax:


JSON Syntax:

{"string": "string"

--key-spec (string)

The length of the data encryption key. Use AES_128 to generate a 128-bit symmetric key, or AES_256 to generate a 256-bit symmetric key.

Possible values:

  • AES_256
  • AES_128

--number-of-bytes (integer)

The length of the data encryption key in bytes. For example, use the value 64 to generate a 512-bit data key (64 bytes is 512 bits). For common key lengths (128-bit and 256-bit symmetric keys), we recommend that you use the KeySpec field instead of this one.

--grant-tokens (list)

A list of grant tokens.

For more information, see Grant Tokens in the AWS Key Management Service Developer Guide .


"string" "string" ...

--cli-input-json (string) Performs service operation based on the JSON string provided. The JSON string follows the format provided by --generate-cli-skeleton. If other arguments are provided on the command line, the CLI values will override the JSON-provided values. It is not possible to pass arbitrary binary values using a JSON-provided value as the string will be taken literally.

--generate-cli-skeleton (string) Prints a JSON skeleton to standard output without sending an API request. If provided with no value or the value input, prints a sample input JSON that can be used as an argument for --cli-input-json. If provided with the value output, it validates the command inputs and returns a sample output JSON for that command.

See 'aws help' for descriptions of global parameters.


CiphertextBlob -> (blob)

The encrypted data encryption key. When you use the HTTP API or the AWS CLI, the value is Base64-encdoded. Otherwise, it is not encoded.

KeyId -> (string)

The identifier of the CMK under which the data encryption key was generated and encrypted.