AWS SDK Version 3 for .NET
API Reference

AWS services or capabilities described in AWS Documentation may vary by region/location. Click Getting Started with Amazon AWS to see specific differences applicable to the China (Beijing) Region.

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

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.

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.

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.

Note:

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

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

Syntax

C#
public virtual EncryptResponse Encrypt(
         EncryptRequest request
)
Parameters
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.

Exceptions

ExceptionCondition
DependencyTimeoutException The system timed out while trying to fulfill the request. The request can be retried.
DisabledException The request was rejected because the specified CMK 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 CMK 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 CMK (CustomerMasterKeySpec). For encrypting, decrypting, re-encrypting, and generating data keys, the KeyUsage must be ENCRYPT_DECRYPT. For signing and verifying, the KeyUsage must be SIGN_VERIFY. To find the KeyUsage of a CMK, use the DescribeKey operation. To find the encryption or signing algorithms supported for a particular CMK, use the DescribeKey operation.
KeyUnavailableException The request was rejected because the specified CMK 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. For more information about how key state affects the use of a CMK, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.
NotFoundException The request was rejected because the specified entity or resource could not be found.

Examples

The following example encrypts data with the specified customer master key (CMK).

To encrypt data


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

            

Version Information

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

Portable Class Library:
Supported in: Windows Store Apps
Supported in: Xamarin Android
Supported in: Xamarin iOS (Unified)
Supported in: Xamarin.Forms

See Also