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Class EncryptCommand

Encrypts plaintext of up to 4,096 bytes using a KMS key. You can use a symmetric or asymmetric KMS key with a KeyUsage of ENCRYPT_DECRYPT.

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

If you use a symmetric encryption 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 spec.

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 encryption 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 encryption 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

  • SM2PKE: 1024 bytes (China Regions only)

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.

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:


Use a bare-bones client and the command you need to make an API call.

import { KMSClient, EncryptCommand } from "@aws-sdk/client-kms"; // ES Modules import
// const { KMSClient, EncryptCommand } = require("@aws-sdk/client-kms"); // CommonJS import
const client = new KMSClient(config);
const command = new EncryptCommand(input);
const response = await client.send(command);

EncryptCommandInput for command's input shape.


EncryptCommandOutput for command's response shape.


config for KMSClient's config shape.







Readonly input

input: EncryptCommandInput

Readonly middlewareStack

middlewareStack: IMiddlewareStack<EncryptCommandInput, EncryptCommandOutput>


Static getEndpointParameterInstructions