AWS SDK Version 3 for .NET
API Reference

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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.

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:


For .NET Core this operation is only available in asynchronous form. Please refer to EncryptAsync.

Namespace: Amazon.KeyManagementService
Assembly: AWSSDK.KeyManagementService.dll
Version: 3.x.y.z


public virtual EncryptResponse Encrypt(
         EncryptRequest request
Type: Amazon.KeyManagementService.Model.EncryptRequest

Container for the necessary parameters to execute the Encrypt service method.

Return Value
The response from the Encrypt service method, as returned by KeyManagementService.


DependencyTimeoutException The system timed out while trying to fulfill the request. You can retry the request.
DisabledException The request was rejected because the specified KMS key is not enabled.
InvalidGrantTokenException The request was rejected because the specified grant token is not valid.
InvalidKeyUsageException The request was rejected for one of the following reasons: The KeyUsage value of the KMS key is incompatible with the API operation. The encryption algorithm or signing algorithm specified for the operation is incompatible with the type of key material in the KMS key (KeySpec). For encrypting, decrypting, re-encrypting, and generating data keys, the KeyUsage must be ENCRYPT_DECRYPT. For signing and verifying messages, the KeyUsage must be SIGN_VERIFY. For generating and verifying message authentication codes (MACs), the KeyUsage must be GENERATE_VERIFY_MAC. To find the KeyUsage of a KMS key, use the DescribeKey operation. To find the encryption or signing algorithms supported for a particular KMS key, use the DescribeKey operation.
KeyUnavailableException The request was rejected because the specified KMS key was not available. You can retry the request.
KMSInternalException The request was rejected because an internal exception occurred. The request can be retried.
KMSInvalidStateException The request was rejected because the state of the specified resource is not valid for this request. This exceptions means one of the following: The key state of the KMS key is not compatible with the operation. To find the key state, use the DescribeKey operation. For more information about which key states are compatible with each KMS operation, see Key states of KMS keys in the Key Management Service Developer Guide. For cryptographic operations on KMS keys in custom key stores, this exception represents a general failure with many possible causes. To identify the cause, see the error message that accompanies the exception.
NotFoundException The request was rejected because the specified entity or resource could not be found.


The following example encrypts data with the specified KMS key.

To encrypt data

var client = new AmazonKeyManagementServiceClient();
var response = client.Encrypt(new EncryptRequest 
    KeyId = "1234abcd-12ab-34cd-56ef-1234567890ab", // The identifier of the KMS key to use for encryption. You can use the key ID or Amazon Resource Name (ARN) of the KMS key, or the name or ARN of an alias that refers to the KMS key.
    Plaintext = new MemoryStream(<binary data>) // The data to encrypt.

MemoryStream ciphertextBlob = response.CiphertextBlob; // The encrypted data (ciphertext).
string keyId = response.KeyId; // The ARN of the KMS key that was used to encrypt the data.


Version Information

.NET Framework:
Supported in: 4.5, 4.0, 3.5

See Also