AWS CLI Command Reference

[ aws . kms ]

generate-data-key

Description

Returns a unique symmetric data key for use outside of KMS. This operation returns a plaintext copy of the data key and a copy that is encrypted under a symmetric encryption KMS key that you specify. The bytes in the plaintext key are random; they are not related to the caller or the KMS key. You can use the plaintext key to encrypt your data outside of KMS and store the encrypted data key with the encrypted data.

To generate a data key, specify the symmetric encryption KMS key that will be used to encrypt the data key. You cannot use an asymmetric KMS key to encrypt data keys. To get the type of your KMS key, use the DescribeKey operation.

You must also specify the length of the data key. Use either the KeySpec or NumberOfBytes parameters (but not both). For 128-bit and 256-bit data keys, use the KeySpec parameter.

To generate an SM4 data key (China Regions only), specify a KeySpec value of AES_128 or NumberOfBytes value of 128 . The symmetric encryption key used in China Regions to encrypt your data key is an SM4 encryption key.

To get only an encrypted copy of the data key, use GenerateDataKeyWithoutPlaintext . To generate an asymmetric data key pair, use the GenerateDataKeyPair or GenerateDataKeyPairWithoutPlaintext operation. To get a cryptographically secure random byte string, use GenerateRandom .

You can use an optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext , you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException . For more information, see Encryption Context in the Key Management Service Developer Guide .

Applications in Amazon Web Services Nitro Enclaves can call this operation by using the Amazon Web Services Nitro Enclaves Development Kit . For information about the supporting parameters, see How Amazon Web Services Nitro Enclaves use KMS in the Key Management Service Developer Guide .

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 .

How to use your data key

We recommend that you use the following pattern to encrypt data locally in your application. You can write your own code or use a client-side encryption library, such as the Amazon Web Services Encryption SDK , the Amazon DynamoDB Encryption Client , or Amazon S3 client-side encryption to do these tasks for you.

To encrypt data outside of KMS:

  • Use the GenerateDataKey operation to get a data key.

  • Use the plaintext data key (in the Plaintext field of the response) to encrypt your data outside of KMS. Then erase the plaintext data key from memory.

  • Store the encrypted data key (in the CiphertextBlob field of the response) with the encrypted data.

To decrypt data outside of KMS:

  • Use the Decrypt operation to decrypt the encrypted data key. The operation returns a plaintext copy of the data key.

  • Use the plaintext data key to decrypt data outside of KMS, then erase the plaintext data key from memory.

Cross-account use : Yes. To perform this operation with a KMS key in a different Amazon Web Services account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions : kms:GenerateDataKey (key policy)

Related operations:

  • Decrypt

  • Encrypt

  • GenerateDataKeyPair

  • GenerateDataKeyPairWithoutPlaintext

  • GenerateDataKeyWithoutPlaintext

See also: AWS API Documentation

Synopsis

  generate-data-key
--key-id <value>
[--encryption-context <value>]
[--number-of-bytes <value>]
[--key-spec <value>]
[--grant-tokens <value>]
[--cli-input-json | --cli-input-yaml]
[--generate-cli-skeleton <value>]
[--debug]
[--endpoint-url <value>]
[--no-verify-ssl]
[--no-paginate]
[--output <value>]
[--query <value>]
[--profile <value>]
[--region <value>]
[--version <value>]
[--color <value>]
[--no-sign-request]
[--ca-bundle <value>]
[--cli-read-timeout <value>]
[--cli-connect-timeout <value>]
[--cli-binary-format <value>]
[--no-cli-pager]
[--cli-auto-prompt]
[--no-cli-auto-prompt]

Options

--key-id (string)

Specifies the symmetric encryption KMS key that encrypts the data key. You cannot specify an asymmetric KMS key or a KMS key in a custom key store. To get the type and origin of your 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 .

--encryption-context (map)

Specifies the encryption context that will be used when encrypting the data key.

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 .

key -> (string)

value -> (string)

Shorthand Syntax:

KeyName1=string,KeyName2=string

JSON Syntax:

{"string": "string"
  ...}

--number-of-bytes (integer)

Specifies the length of the data key in bytes. For example, use the value 64 to generate a 512-bit data key (64 bytes is 512 bits). For 128-bit (16-byte) and 256-bit (32-byte) data keys, use the KeySpec parameter.

You must specify either the KeySpec or the NumberOfBytes parameter (but not both) in every GenerateDataKey request.

--key-spec (string)

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

You must specify either the KeySpec or the NumberOfBytes parameter (but not both) in every GenerateDataKey request.

Possible values:

  • AES_256

  • AES_128

--grant-tokens (list)

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 .

(string)

Syntax:

"string" "string" ...

--cli-input-json | --cli-input-yaml (string) Reads arguments from the JSON string provided. The JSON string follows the format provided by --generate-cli-skeleton. If other arguments are provided on the command line, those 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. This may not be specified along with --cli-input-yaml.

--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. Similarly, if provided yaml-input it will print a sample input YAML that can be used with --cli-input-yaml. If provided with the value output, it validates the command inputs and returns a sample output JSON for that command. The generated JSON skeleton is not stable between versions of the AWS CLI and there are no backwards compatibility guarantees in the JSON skeleton generated.

Global Options

--debug (boolean)

Turn on debug logging.

--endpoint-url (string)

Override command’s default URL with the given URL.

--no-verify-ssl (boolean)

By default, the AWS CLI uses SSL when communicating with AWS services. For each SSL connection, the AWS CLI will verify SSL certificates. This option overrides the default behavior of verifying SSL certificates.

--no-paginate (boolean)

Disable automatic pagination.

--output (string)

The formatting style for command output.

  • json

  • text

  • table

  • yaml

  • yaml-stream

--query (string)

A JMESPath query to use in filtering the response data.

--profile (string)

Use a specific profile from your credential file.

--region (string)

The region to use. Overrides config/env settings.

--version (string)

Display the version of this tool.

--color (string)

Turn on/off color output.

  • on

  • off

  • auto

--no-sign-request (boolean)

Do not sign requests. Credentials will not be loaded if this argument is provided.

--ca-bundle (string)

The CA certificate bundle to use when verifying SSL certificates. Overrides config/env settings.

--cli-read-timeout (int)

The maximum socket read time in seconds. If the value is set to 0, the socket read will be blocking and not timeout. The default value is 60 seconds.

--cli-connect-timeout (int)

The maximum socket connect time in seconds. If the value is set to 0, the socket connect will be blocking and not timeout. The default value is 60 seconds.

--cli-binary-format (string)

The formatting style to be used for binary blobs. The default format is base64. The base64 format expects binary blobs to be provided as a base64 encoded string. The raw-in-base64-out format preserves compatibility with AWS CLI V1 behavior and binary values must be passed literally. When providing contents from a file that map to a binary blob fileb:// will always be treated as binary and use the file contents directly regardless of the cli-binary-format setting. When using file:// the file contents will need to properly formatted for the configured cli-binary-format.

  • base64

  • raw-in-base64-out

--no-cli-pager (boolean)

Disable cli pager for output.

--cli-auto-prompt (boolean)

Automatically prompt for CLI input parameters.

--no-cli-auto-prompt (boolean)

Disable automatically prompt for CLI input parameters.

Examples

Note

To use the following examples, you must have the AWS CLI installed and configured. See the Getting started guide in the AWS CLI User Guide for more information.

Unless otherwise stated, all examples have unix-like quotation rules. These examples will need to be adapted to your terminal’s quoting rules. See Using quotation marks with strings in the AWS CLI User Guide .

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 AWS. 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 AWS 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.

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 512

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 AWS Key Management Service Developer Guide.

Output

CiphertextBlob -> (blob)

The encrypted copy of the data key. When you use the HTTP API or the Amazon Web Services CLI, the value is Base64-encoded. Otherwise, it is not Base64-encoded.

Plaintext -> (blob)

The plaintext data key. When you use the HTTP API or the Amazon Web Services CLI, the value is Base64-encoded. Otherwise, it is not Base64-encoded. Use this data key to encrypt your data outside of KMS. Then, remove it from memory as soon as possible.

KeyId -> (string)

The Amazon Resource Name (key ARN ) of the KMS key that encrypted the data key.

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