[ aws . kms ]

generate-random

Description

Returns a random byte string that is cryptographically secure.

You must use the NumberOfBytes parameter to specify the length of the random byte string. There is no default value for string length.

By default, the random byte string is generated in KMS. To generate the byte string in the CloudHSM cluster that is associated with a custom key store , specify the custom key store ID.

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 .

For more information about entropy and random number generation, see Key Management Service Cryptographic Details .

Cross-account use : Not applicable. GenerateRandom does not use any account-specific resources, such as KMS keys.

Required permissions : kms:GenerateRandom (IAM policy)

See also: AWS API Documentation

See ‘aws help’ for descriptions of global parameters.

Synopsis

  generate-random
[--number-of-bytes <value>]
[--custom-key-store-id <value>]
[--cli-input-json | --cli-input-yaml]
[--generate-cli-skeleton <value>]

Options

--number-of-bytes (integer)

The length of the random byte string. This parameter is required.

--custom-key-store-id (string)

Generates the random byte string in the CloudHSM cluster that is associated with the specified custom key store . To find the ID of a custom key store, use the DescribeCustomKeyStores operation.

--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.

See ‘aws help’ for descriptions of global 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 random byte string (Linux or macOs)

The following generate-random example generates a 256-bit (32-byte), base64-encoded random byte string. The example decodes the byte string and saves it in the random file.

When you run this command, you must use the number-of-bytes parameter to specify the length of the random value in bytes.

You don’t specify a KMS key when you run this command. The random byte string is unrelated to any KMS key.

By default, AWS KMS generates the random number. However, if you specify a `custom key store<https://docs.aws.amazon.com/kms/latest/developerguide/custom-key-store-overview.html>`__, the random byte string is generated in the AWS CloudHSM cluster associated with the custom key store.

This example uses the following parameters and values:

  • It uses the required --number-of-bytes parameter with a value of 32 to request a 32-byte (256-bit) string.

  • It uses the --output parameter with a value of text to direct the AWS CLI to return the output as text, instead of JSON.

  • It uses the --query parameter to extract the value of the Plaintext property from the response.

  • It pipes ( | ) the output of the command to the base64 utility, which decodes the extracted output.

  • It uses the redirection operator ( > ) to save decoded byte string to the ExampleRandom file.

  • It uses the redirection operator ( > ) to save the binary ciphertext to a file.

    aws kms generate-random \
        --number-of-bytes 32 \
        --output text \
        --query Plaintext | base64 --decode > ExampleRandom
    

This command produces no output.

For more information, see GenerateRandom in the AWS Key Management Service API Reference.

Example 2: To generate a 256-bit random number (Windows Command Prompt)

The following example uses the generate-random command to generate a 256-bit (32-byte), base64-encoded random byte string. The example decodes the byte string and saves it in the random file. This example is the same as the previous example, except that it uses the certutil utility in Windows to base64-decode the random byte string before saving it in a file.

First, generate a base64-encoded random byte string and saves it in a temporary file, ExampleRandom.base64.

aws kms generate-random \
    --number-of-bytes 32 \
    --output text \
    --query Plaintext > ExampleRandom.base64

Because the output of the generate-random command is saved in a file, this example produces no output.

Now use the certutil -decode command to decode the base64-encoded byte string in the ExampleRandom.base64 file. Then, it saves the decoded byte string in the ExampleRandom file.

certutil -decode ExampleRandom.base64 ExampleRandom

Output:

Input Length = 18
Output Length = 12
CertUtil: -decode command completed successfully.

For more information, see GenerateRandom in the AWS Key Management Service API Reference.

Output

Plaintext -> (blob)

The random byte string. When you use the HTTP API or the Amazon Web Services CLI, the value is Base64-encoded. Otherwise, it is not Base64-encoded.