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[ aws . kms ]

encrypt

Description

Encrypts plaintext into ciphertext by using a KMS key. 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 Amazon Web Services 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 KMS key 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 KMS key to use in the encryption operation. The KMS key must have a KeyUsage value of ENCRYPT_DECRYPT. To find the KeyUsage of a KMS key, use the DescribeKey operation.

If you use a symmetric KMS key, 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 Key Management Service Developer Guide .

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

Warning

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

You are not required to supply the key ID and encryption algorithm when you decrypt with symmetric KMS keys because KMS stores this information in the ciphertext blob. 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 KMS key and the encryption algorithm that you choose.

  • Symmetric KMS keys
    • 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 KMS key that you use for this operation must be in a compatible key state. For details, see Key state: Effect on your KMS key in the Key Management Service Developer Guide .

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:Encrypt (key policy)

Related operations:

  • Decrypt
  • GenerateDataKey
  • GenerateDataKeyPair

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 <value>]
[--generate-cli-skeleton <value>]

Options

--key-id (string)

Identifies the KMS key to use in the encryption 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 .

--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 KMS key. The standard asymmetric encryption algorithms that 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 KMS key, but it is highly 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"
  ...}

--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" ...

--encryption-algorithm (string)

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

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

Possible values:

  • SYMMETRIC_DEFAULT
  • RSAES_OAEP_SHA_1
  • RSAES_OAEP_SHA_256

--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.

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 Amazon Web Services CLI, the value is Base64-encoded. Otherwise, it is not Base64-encoded.

KeyId -> (string)

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

EncryptionAlgorithm -> (string)

The encryption algorithm that was used to encrypt the plaintext.