Table Of Contents


User Guide

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

[ aws . kms ]



Encrypts plaintext into ciphertext by using a customer master key. The encrypt function has two primary use cases:

  • You can encrypt up to 4 KB of arbitrary data such as an RSA key, a database password, or other sensitive customer information.
  • If you are moving encrypted data from one region to another, you can use this API to encrypt in the new region the plaintext data key that was used to encrypt the data in the original region. This provides you with an encrypted copy of the data key that can be decrypted in the new region and used there to decrypt the encrypted data.

Unless you are moving encrypted data from one region to another, you don't use this function to encrypt a generated data key within a region. You retrieve data keys already encrypted by calling the generate-data-key or generate-data-key-without-plaintext function. Data keys don't need to be encrypted again by calling encrypt .

If you want to encrypt data locally in your application, you can use the generate-data-key function to return a plaintext data encryption key and a copy of the key encrypted under the customer master key (CMK) of your choosing.

See also: AWS API Documentation


--key-id <value>
--plaintext <value>
[--encryption-context <value>]
[--grant-tokens <value>]
[--cli-input-json <value>]
[--generate-cli-skeleton <value>]


--key-id (string)

A unique identifier for the customer master key. This value can be a globally unique identifier, a fully specified ARN to either an alias or a key, or an alias name prefixed by "alias/".

  • Key ARN Example - arn:aws:kms:us-east-1:123456789012:key/12345678-1234-1234-1234-123456789012
  • Alias ARN Example - arn:aws:kms:us-east-1:123456789012:alias/MyAliasName
  • Globally Unique Key ID Example - 12345678-1234-1234-1234-123456789012
  • Alias Name Example - alias/MyAliasName

--plaintext (blob)

Data to be encrypted.

--encryption-context (map)

Name-value pair that specifies the encryption context to be used for authenticated encryption. If used here, the same value must be supplied to the decrypt API or decryption will fail. For more information, see Encryption Context .

Shorthand Syntax:


JSON Syntax:

{"string": "string"

--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.

--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.


The following command demonstrates the recommended way to encrypt data with the AWS CLI.

aws kms encrypt --key-id 1234abcd-12ab-34cd-56ef-1234567890ab --plaintext fileb://ExamplePlaintextFile --output text --query CiphertextBlob | base64 --decode > ExampleEncryptedFile

The command does several things:

  1. Uses the fileb:// prefix to specify the --plaintext parameter.

    The fileb:// prefix instructs the CLI to read the data to encrypt, called the plaintext, from a file and pass the file's contents to the command's --plaintext parameter. If the file is not in the current directory, type the full path to file. For example: fileb:///var/tmp/ExamplePlaintextFile or fileb://C:\Temp\ExamplePlaintextFile.

    For more information about reading AWS CLI parameter values from a file, see Loading Parameters from a File in the AWS Command Line Interface User Guide and Best Practices for Local File Parameters on the AWS Command Line Tool Blog.

  2. Uses the --output and --query parameters to control the command's output.

    These parameters extract the encrypted data, called the ciphertext, from the command's output.

    For more information about controlling output, see Controlling Command Output in the AWS Command Line Interface User Guide.

  3. Uses the base64 utility to decode the extracted output.

    This utility decodes the extracted ciphertext to binary data. The ciphertext that is returned by a successful encrypt command is base64-encoded text. You must decode this text before you can use the AWS CLI to decrypt it.

  4. Saves the binary ciphertext to a file.

    The final part of the command (> ExampleEncryptedFile) saves the binary ciphertext to a file to make decryption easier. For an example command that uses the AWS CLI to decrypt data, see the decrypt examples.

Example: Using the AWS CLI to encrypt data from the Windows command prompt

The preceding example assumes the base64 utility is available, which is commonly the case on Linux and Mac OS X. For the Windows command prompt, use certutil instead of base64. This requires two commands, as shown in the following examples.

aws kms encrypt --key-id 1234abcd-12ab-34cd-56ef-1234567890ab --plaintext fileb://ExamplePlaintextFile --output text --query CiphertextBlob > C:\Temp\ExampleEncryptedFile.base64
certutil -decode C:\Temp\ExampleEncryptedFile.base64 C:\Temp\ExampleEncryptedFile


CiphertextBlob -> (blob)

The encrypted plaintext. If you are using the CLI, the value is Base64 encoded. Otherwise, it is not encoded.

KeyId -> (string)

The ID of the key used during encryption.