[ aws . kms ]

encrypt

Description

Encrypts plaintext into ciphertext by using a customer master key (CMK). The Encrypt operation has two primary use cases:

• You can encrypt small amounts of arbitrary data, such as a personal identifier or database password, or other sensitive information.

• You can use the Encrypt operation to move encrypted data from one AWS Region to another. For example, in Region A, generate a data key and use the plaintext key to encrypt your data. Then, in Region A, use the Encrypt operation to encrypt the plaintext data key under a CMK in Region B. Now, you can move the encrypted data and the encrypted data key to Region B. When necessary, you can decrypt the encrypted data key and the encrypted data entirely within in Region B.

You don’t need to use the Encrypt operation to encrypt a data key. The GenerateDataKey and GenerateDataKeyPair operations return a plaintext data key and an encrypted copy of that data key.

When you encrypt data, you must specify a symmetric or asymmetric CMK to use in the encryption operation. The CMK must have a KeyUsage value of ENCRYPT_DECRYPT. To find the KeyUsage of a CMK, use the DescribeKey operation.

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

If you specify an asymmetric CMK, you must also specify the encryption algorithm. The algorithm must be compatible with the CMK type.

Warning

When you use an asymmetric CMK to encrypt or reencrypt data, be sure to record the CMK and encryption algorithm that you choose. You will be required to provide the same CMK and encryption algorithm when you decrypt the data. If the CMK and algorithm do not match the values used to encrypt the data, the decrypt operation fails.

You are not required to supply the CMK ID and encryption algorithm when you decrypt with symmetric CMKs because AWS KMS stores this information in the ciphertext blob. AWS KMS cannot store metadata in ciphertext generated with asymmetric keys. The standard format for asymmetric key ciphertext does not include configurable fields.

The maximum size of the data that you can encrypt varies with the type of CMK and the encryption algorithm that you choose.

• Symmetric CMKs

  • SYMMETRIC_DEFAULT : 4096 bytes

• RSA_2048

  • RSAES_OAEP_SHA_1 : 214 bytes

  • RSAES_OAEP_SHA_256 : 190 bytes

• RSA_3072

  • RSAES_OAEP_SHA_1 : 342 bytes

  • RSAES_OAEP_SHA_256 : 318 bytes

• RSA_4096

  • RSAES_OAEP_SHA_1 : 470 bytes

  • RSAES_OAEP_SHA_256 : 446 bytes

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide .

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.

See also: AWS API Documentation

See ‘aws help’ for descriptions of global parameters.

Synopsis

  encrypt
--key-id <value>
--plaintext <value>
[--encryption-context <value>]
[--grant-tokens <value>]
[--encryption-algorithm <value>]
[--cli-input-json | --cli-input-yaml]
[--generate-cli-skeleton <value>]
[--cli-auto-prompt <value>]

Options

--key-id (string)

A unique identifier for the customer master key (CMK).

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 .

--plaintext (blob)

Data to be encrypted.

--encryption-context (map)

Specifies the encryption context that will be used to encrypt the data. An encryption context is valid only for cryptographic operations with a symmetric CMK. The standard asymmetric encryption algorithms that AWS KMS uses do not support an encryption context.

An encryption context is a collection of non-secret key-value pairs that represents 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 optional when encrypting with a symmetric CMK, but it is highly recommended.

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

key -> (string)

value -> (string)

Shorthand Syntax:

KeyName1=string,KeyName2=string

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)

Syntax:

"string" "string" ...

--encryption-algorithm (string)

Specifies the encryption algorithm that AWS KMS will use to encrypt the plaintext message. The algorithm must be compatible with the CMK that you specify.

This parameter is required only for asymmetric CMKs. The default value, SYMMETRIC_DEFAULT , is the algorithm used for symmetric CMKs. If you are using an asymmetric CMK, we recommend RSAES_OAEP_SHA_256.

Possible values:

• SYMMETRIC_DEFAULT

• RSAES_OAEP_SHA_1

• RSAES_OAEP_SHA_256

--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.

--cli-auto-prompt (boolean) Automatically prompt for CLI input parameters.

See ‘aws help’ for descriptions of global parameters.

Examples

Example 1: To encrypt the contents of a file on Linux or MacOS

The following encrypt 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 2: Using the AWS CLI to encrypt data on Windows

The preceding example assumes the base64 utility is available, which is commonly the case on Linux and MacOS. 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

Output

CiphertextBlob -> (blob)

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

KeyId -> (string)

The Amazon Resource Name (key ARN ) of the CMK that was used to encrypt the plaintext.

EncryptionAlgorithm -> (string)

The encryption algorithm that was used to encrypt the plaintext.