# Decrypt
<a name="ct-decrypt"></a>

These examples show AWS CloudTrail log entries for the [Decrypt](https://docs.aws.amazon.com/kms/latest/APIReference/API_Decrypt.html) operation.

The CloudTrail log entry for a `Decrypt` operation always includes the `encryptionAlgorithm` in the `requestParameters` even if the encryption algorithm wasn't specified in the request. The ciphertext in the request and the plaintext in the response are omitted.

**Topics**
+ [Decrypt with a standard symmetric encryption key](#ct-decrypt-default)
+ [Decrypt failure with a standard symmetric encryption key](#ct-decrypt-fail)
+ [Decrypt with a KMS key in an AWS CloudHSM key store](#ct-decrypt-hsm)
+ [Decrypt with a KMS key in an external key store](#ct-decrypt-xks)
+ [Decrypt failure with a KMS key in an external key store](#ct-decrypt-xks-fail)
+ [Decrypt with a standard symmetric encryption key over a post-quantum TLS connection](#ct-decrypt-default-pqtls)

## Decrypt with a standard symmetric encryption key
<a name="ct-decrypt-default"></a>

The following is an example CloudTrail log entry for a `Decrypt` operation with a standard symmetric encryption key. 

```
{
    "eventVersion": "1.11",
    "userIdentity": {
        "type": "IAMUser",
        "principalId": "EX_PRINCIPAL_ID",
        "arn": "arn:aws:iam::111122223333:user/Alice",
        "accountId": "111122223333",
        "accessKeyId": "EXAMPLE_KEY_ID",
        "userName": "Alice"
    },
    "eventTime": "2025-05-20T20:45:00Z",
    "eventSource": "kms.amazonaws.com",
    "eventName": "Decrypt",
    "awsRegion": "us-west-2",
    "sourceIPAddress": "192.0.2.0",
    "userAgent": "AWS Internal",
    "requestParameters": {
        "encryptionAlgorithm": "SYMMETRIC_DEFAULT",
        "keyId": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab",
        "encryptionContext": {
            "Department": "Engineering",
            "Project": "Alpha"
        }        
    },
    "responseElements": null,
    "additionalEventData": {
        "keyMaterialId": "123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0"
    },
    "requestID": "12345126-30d5-4b28-98b9-9153da559963",
    "eventID": "abcde202-ba1a-467c-b4ba-f729d45ae521",
    "readOnly": true,
    "resources": [
        {
            "accountId": "111122223333",
            "type": "AWS::KMS::Key",
            "ARN": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab"
        }
    ],
    "eventType": "AwsApiCall",
    "managementEvent": true,
    "recipientAccountId": "111122223333",
    "eventCategory": "Management",
    "tlsDetails": {
        "tlsVersion": "TLSv1.2",
        "cipherSuite": "ECDHE-RSA-AES256-GCM-SHA384",
        "clientProvidedHostHeader": "kms.us-west-2.amazonaws.com"
    }
}
```

## Decrypt failure with a standard symmetric encryption key
<a name="ct-decrypt-fail"></a>

The following example CloudTrail log entry records a failed `Decrypt` operation with a standard symmetric encryption KMS key. The exception (`errorCode`) and error message (`errorMessage`) are included help you to resolve the error.

In this case, the symmetric encryption KMS key specified in the `Decrypt` request was not the symmetric encryption KMS key that was used to encrypt the data.

```
{
    "eventVersion": "1.08",
    "userIdentity": {
        "type": "IAMUser",
        "principalId": "EX_PRINCIPAL_ID",
        "arn": "arn:aws:iam::111122223333:user/Alice",
        "accountId": "111122223333",
        "accessKeyId": "EXAMPLE_KEY_ID",
        "userName": "Alice"
    },
    "eventTime": "2022-11-24T18:57:43Z",
    "eventSource": "kms.amazonaws.com",
    "eventName": "Decrypt",
    "awsRegion": "us-west-2",
    "sourceIPAddress": "192.0.2.0",
    "userAgent": "AWS Internal",
    "errorCode": "IncorrectKeyException"
    "errorMessage": "The key ID in the request does not identify a CMK that can perform this operation.",
    "requestParameters": {
        "encryptionAlgorithm": "SYMMETRIC_DEFAULT",
        "keyId": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab",
        "encryptionContext": {
            "Department": "Engineering",
            "Project": "Alpha"
        }        
    },
    "responseElements": null,
    "requestID": "22345126-30d5-4b28-98b9-9153da559963",
    "eventID": "abcde202-ba1a-467c-b4ba-f729d45ae521",
    "readOnly": true,
    "resources": [
        {
            "accountId": "111122223333",
            "type": "AWS::KMS::Key",
            "ARN": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab"
        }
    ],
    "eventType": "AwsApiCall",
    "recipientAccountId": "111122223333"
}
```

## Decrypt with a KMS key in an AWS CloudHSM key store
<a name="ct-decrypt-hsm"></a>

The following example CloudTrail log entry records a `Decrypt` operation with a KMS key in an [AWS CloudHSM key store](keystore-cloudhsm.md). All log entries for cryptographic operations with a KMS key in a custom key store include an `additionalEventData` field with the `customKeyStoreId` and `backingKeyId`. The value returned in the `backingKeyId` field is the CloudHSM key `id` attribute. The `additionalEventData` isn't specified in the request.

```
{
    "eventVersion": "1.08",
    "userIdentity": {
        "type": "IAMUser",
        "principalId": "EX_PRINCIPAL_ID",
        "arn": "arn:aws:iam::111122223333:user/Alice",
        "accountId": "111122223333",
        "accessKeyId": "EXAMPLE_KEY_ID",
        "userName": "Alice"
    },
    "eventTime": "2021-10-26T23:41:27Z",
    "eventSource": "kms.amazonaws.com",
    "eventName": "Decrypt",
    "awsRegion": "us-west-2",
    "sourceIPAddress": "192.0.2.0",
    "requestParameters": {
        "encryptionAlgorithm": "SYMMETRIC_DEFAULT",
        "keyId": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab",
        "encryptionContext": {
            "Department": "Development",
            "Purpose": "Test"
        }
    },
    "responseElements": null,
    "additionalEventData": {
        "customKeyStoreId": "cks-1234567890abcdef0"
    },
    "requestID": "e1b881f8-2048-41f8-b6cc-382b7857ec61",
    "eventID": "a79603d5-4cde-46fc-819c-a7cf547b9df4",
    "readOnly": true,
    "resources": [
        {
            "accountId": "111122223333",
            "type": "AWS::KMS::Key",
            "ARN": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab"
        }
    ],
    "eventType": "AwsApiCall",
    "managementEvent": true,
    "recipientAccountId": "111122223333",
    "eventCategory": "Management"    
}
```

## Decrypt with a KMS key in an external key store
<a name="ct-decrypt-xks"></a>

The following example CloudTrail log entry records a `Decrypt` operation with a KMS key in an [external key store](keystore-external.md). In addition to the `customKeyStoreId`, the `additionalEventData` field includes the [external key ID](keystore-external.md#concept-external-key) (`XksKeyId`). The `additionalEventData` isn't specified in the request.

```
{
    "eventVersion": "1.08",
    "userIdentity": {
        "type": "IAMUser",
        "principalId": "EX_PRINCIPAL_ID",
        "arn": "arn:aws:iam::111122223333:user/Alice",
        "accountId": "111122223333",
        "accessKeyId": "EXAMPLE_KEY_ID",
        "userName": "Alice"
    },
    "eventTime": "2022-11-24T00:26:58Z",
    "eventSource": "kms.amazonaws.com",
    "eventName": "Decrypt",
    "awsRegion": "us-west-2",
    "sourceIPAddress": "AWS Internal",
    "requestParameters": {
        "encryptionAlgorithm": "SYMMETRIC_DEFAULT",
        "keyId": "arn:aws:kms:us-west-2:111122223333:key/0987dcba-09fe-87dc-65ba-ab0987654321",
        "encryptionContext": {
            "Department": "Engineering",
            "Purpose": "Test"
        }
    },
    "responseElements": null,
    "additionalEventData": {
        "customKeyStoreId": "cks-9876543210fedcba9",
        "xksKeyId": "abc01234567890fe"
    },
    "requestID": "f1b881f8-2048-41f8-b6cc-382b7857ec61",
    "eventID": "b79603d5-4cde-46fc-819c-a7cf547b9df4",
    "readOnly": true,
    "resources": [
        {
            "accountId": "111122223333",
            "type": "AWS::KMS::Key",
            "ARN": "arn:aws:kms:us-west-2:111122223333:key/0987dcba-09fe-87dc-65ba-ab0987654321"
        }
    ],
    "eventType": "AwsApiCall",
    "managementEvent": true,
    "recipientAccountId": "111122223333",
    "eventCategory": "Management"
}
```

## Decrypt failure with a KMS key in an external key store
<a name="ct-decrypt-xks-fail"></a>

The following example CloudTrail log entry records a failed request for a `Decrypt` operation with a KMS key in an [external key store](keystore-external.md). CloudWatch logs requests that fail, in addition to successful requests. When recording a failure, the CloudTrail log entry includes the exception (errorCode) and the accompanying error message (errorMessage).

If the failed request reached your external key store proxy, as in this example, you can use the `requestId` value to associate the failed request with a corresponding request your external key store proxy logs, if your proxy provides them.

For help with `Decrypt` requests in external key stores, see [Decryption errors](xks-troubleshooting.md#fix-xks-decrypt).

```
{
    "eventVersion": "1.08",
    "userIdentity": {
        "type": "IAMUser",
        "principalId": "EX_PRINCIPAL_ID",
        "arn": "arn:aws:iam::111122223333:user/Alice",
        "accountId": "111122223333",
        "accessKeyId": "EXAMPLE_KEY_ID",
        "userName": "Alice"
    },
    "eventTime": "2022-11-24T00:26:58Z",
    "eventSource": "kms.amazonaws.com",
    "eventName": "Decrypt",
    "awsRegion": "us-west-2",
    "sourceIPAddress": "AWS Internal",
    "userAgent": "AWS Internal",
    "errorCode": "KMSInvalidStateException",
    "errorMessage": "The external key store proxy rejected the request because the specified ciphertext or additional authenticated data is corrupted, missing, or otherwise invalid.",
    "requestParameters": {
        "encryptionAlgorithm": "SYMMETRIC_DEFAULT",
        "keyId": "arn:aws:kms:us-west-2:111122223333:key/0987dcba-09fe-87dc-65ba-ab0987654321",
        "encryptionContext": {
            "Department": "Engineering",
            "Purpose": "Test"
        }
    },
    "responseElements": null,
    "additionalEventData": {
        "customKeyStoreId": "cks-9876543210fedcba9",
        "xksKeyId": "abc01234567890fe"
    },
    "requestID": "f1b881f8-2048-41f8-b6cc-382b7857ec61",
    "eventID": "b79603d5-4cde-46fc-819c-a7cf547b9df4",
    "readOnly": true,
    "resources": [
        {
            "accountId": "111122223333",
            "type": "AWS::KMS::Key",
            "ARN": "arn:aws:kms:us-west-2:111122223333:key/0987dcba-09fe-87dc-65ba-ab0987654321"
        }
    ],
    "eventType": "AwsApiCall",
    "managementEvent": true,
    "recipientAccountId": "111122223333",
    "eventCategory": "Management"
}
```

## Decrypt with a standard symmetric encryption key over a post-quantum TLS connection
<a name="ct-decrypt-default-pqtls"></a>

The following is an example CloudTrail log entry for a `Decrypt` operation with a standard symmetric encryption key over a post-quantum TLS connection. The keyExchange field in the `tlsDetails` section mentions `X25519MLKEM768`. This is a *hybrid* algorithm that combines [Elliptic Curve Diffie-Hellman](https://en.wikipedia.org/wiki/Elliptic-curve_Diffie%E2%80%93Hellman) (ECDH) over [Curve 25519](https://en.wikipedia.org/wiki/Curve25519), a classic key exchange algorithm used today in TLS, with [Module-Lattice-Based Key-Encapsulation Mechanism](https://csrc.nist.gov/pubs/fips/203/final) (ML-KEM), a public-key encryption and key-establishment algorithm that the National Institute for Standards and Technology (NIST) [ has designated as its first standard](https://csrc.nist.gov/pubs/fips/203/final) post-quantum key-agreement algorithm.

```
{
    "eventVersion": "1.11",
    "userIdentity": {
        "type": "IAMUser",
        "principalId": "EX_PRINCIPAL_ID",
        "arn": "arn:aws:iam::111122223333:user/Alice",
        "accountId": "111122223333",
        "accessKeyId": "EXAMPLE_KEY_ID",
        "userName": "Alice"
    },
    "eventTime": "2025-11-12T15:16:26Z",
    "eventSource": "kms.amazonaws.com",
    "eventName": "Decrypt",
    "awsRegion": "us-west-2",
    "sourceIPAddress": "192.0.2.0",
    "userAgent": "aws-sdk-java/2.30.22 md/io#async md/http#AwsCommonRuntime ...",
    "requestParameters": {
        "encryptionAlgorithm": "SYMMETRIC_DEFAULT",
        "keyId": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab",
        "encryptionContext": {
            "Department": "Engineering",
            "Project": "Alpha"
        }
    },
    "responseElements": null,
    "additionalEventData": {
        "keyMaterialId": "123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0"
    },
    "requestID": "12345126-30d5-4b28-98b9-9153da559963",
    "eventID": "abcde202-ba1a-467c-b4ba-f729d45ae521",
    "readOnly": true,
    "resources": [
        {
            "accountId": "111122223333",
            "type": "AWS::KMS::Key",
            "ARN": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab"
        }
    ],
    "eventType": "AwsApiCall",
    "managementEvent": true,
    "recipientAccountId": "111122223333",
    "eventCategory": "Management",
    "tlsDetails": {
        "tlsVersion": "TLSv1.3",
        "cipherSuite": "TLS_AES_256_GCM_SHA384",
        "clientProvidedHostHeader": "kms.us-west-2.amazonaws.com",
        "keyExchange": "X25519MLKEM768"
    }
}
```