# Data encryption at rest for AWS Lambda
Encryption at rest

Lambda always provides at-rest encryption for the following resources using an [AWS owned key](https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#aws-owned-cmk) or an [AWS managed key](https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#aws-managed-cmk):
+ Environment variables
+ Files that you upload to Lambda, including deployment packages and layer archives
+ Event source mapping filter criteria objects

You can optionally configure Lambda to use a customer managed key to encrypt your [environment variables](configuration-envvars-encryption.md), [.zip deployment packages](encrypt-zip-package.md), and [filter criteria objects](invocation-eventfiltering.md#filter-criteria-encryption).

Amazon CloudWatch Logs and AWS X-Ray also encrypt data by default, and can be configured to use a customer managed key. For details, see [ Encrypt log data in CloudWatch Logs](https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/encrypt-log-data-kms.html) and [Data protection in AWS X-Ray](https://docs.aws.amazon.com/xray/latest/devguide/xray-console-encryption.html).

## Monitoring your encryption keys for Lambda


When you use an AWS KMS customer managed key with Lambda, you can use [AWS CloudTrail](https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudtrail-user-guide.html). The following examples are CloudTrail events for `Decrypt`, `DescribeKey`, and `GenerateDataKey` calls made by Lambda to access data encrypted by your customer managed key.

------
#### [ Decrypt ]

If you used a AWS KMS customer managed key to encrypt your [filter criteria](invocation-eventfiltering.md#filter-criteria-encryption) object, Lambda sends a `Decrypt` request on your behalf when you try to access it in plaintext (for example, from a `ListEventSourceMappings` call). The following example event records the `Decrypt` operation:

```
{
    "eventVersion": "1.09",
    "userIdentity": {
        "type": "AssumedRole",
        "principalId": "AROA123456789EXAMPLE:example",
        "arn": "arn:aws:sts::123456789012:assumed-role/role-name/example",
        "accountId": "123456789012",
        "accessKeyId": "ASIAIOSFODNN7EXAMPLE",
        "sessionContext": {
            "sessionIssuer": {
                "type": "Role",
                "principalId": "AROA123456789EXAMPLE",
                "arn": "arn:aws:iam::123456789012:role/role-name",
                "accountId": "123456789012",
                "userName": "role-name"
            },
            "attributes": {
                "creationDate": "2024-05-30T00:45:23Z",
                "mfaAuthenticated": "false"
            }
        },
        "invokedBy": "lambda.amazonaws.com"
    },
    "eventTime": "2024-05-30T01:05:46Z",
    "eventSource": "kms.amazonaws.com",
    "eventName": "Decrypt",
    "awsRegion": "eu-west-1",
    "sourceIPAddress": "lambda.amazonaws.com",
    "userAgent": "lambda.amazonaws.com",
    "requestParameters": {
        "keyId": "arn:aws:kms:eu-west-1:123456789012:key/a1b2c3d4-5678-90ab-cdef-EXAMPLE11111",
        "encryptionContext": {
            "aws-crypto-public-key": "ABCD+7876787678+CDEFGHIJKL/888666888999888555444111555222888333111==",
            "aws:lambda:EventSourceArn": "arn:aws:sqs:eu-west-1:123456789012:sample-source",
            "aws:lambda:FunctionArn": "arn:aws:lambda:eu-west-1:123456789012:function:sample-function"
        },
        "encryptionAlgorithm": "SYMMETRIC_DEFAULT"
    },
    "responseElements": null,
    "requestID": "a1b2c3d4-5678-90ab-cdef-EXAMPLEaaaaa",
    "eventID": "a1b2c3d4-5678-90ab-cdef-EXAMPLEbbbbb",
    "readOnly": true,
    "resources": [
        {
            "accountId": "AWS Internal",
            "type": "AWS::KMS::Key",
            "ARN": "arn:aws:kms:eu-west-1:123456789012:key/a1b2c3d4-5678-90ab-cdef-EXAMPLE11111"
        }
    ],
    "eventType": "AwsApiCall",
    "managementEvent": true,
    "recipientAccountId": "123456789012",
    "eventCategory": "Management",
    "sessionCredentialFromConsole": "true"
}
```

------
#### [ DescribeKey ]

If you used a AWS KMS customer managed key to encrypt your [filter criteria](invocation-eventfiltering.md#filter-criteria-encryption) object, Lambda sends a `DescribeKey` request on your behalf when you try to access it (for example, from a `GetEventSourceMapping` call). The following example event records the `DescribeKey` operation:

```
{
    "eventVersion": "1.09",
    "userIdentity": {
        "type": "AssumedRole",
        "principalId": "AROA123456789EXAMPLE:example",
        "arn": "arn:aws:sts::123456789012:assumed-role/role-name/example",
        "accountId": "123456789012",
        "accessKeyId": "ASIAIOSFODNN7EXAMPLE",
        "sessionContext": {
            "sessionIssuer": {
                "type": "Role",
                "principalId": "AROA123456789EXAMPLE",
                "arn": "arn:aws:iam::123456789012:role/role-name",
                "accountId": "123456789012",
                "userName": "role-name"
            },
            "attributes": {
                "creationDate": "2024-05-30T00:45:23Z",
                "mfaAuthenticated": "false"
            }
        }
    },
    "eventTime": "2024-05-30T01:09:40Z",
    "eventSource": "kms.amazonaws.com",
    "eventName": "DescribeKey",
    "awsRegion": "eu-west-1",
    "sourceIPAddress": "54.240.197.238",
    "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36",
    "requestParameters": {
        "keyId": "a1b2c3d4-5678-90ab-cdef-EXAMPLE11111"
    },
    "responseElements": null,
    "requestID": "a1b2c3d4-5678-90ab-cdef-EXAMPLEaaaaa",
    "eventID": "a1b2c3d4-5678-90ab-cdef-EXAMPLEbbbbb",
    "readOnly": true,
    "resources": [
        {
            "accountId": "AWS Internal",
            "type": "AWS::KMS::Key",
            "ARN": "arn:aws:kms:eu-west-1:123456789012:key/a1b2c3d4-5678-90ab-cdef-EXAMPLE11111"
        }
    ],
    "eventType": "AwsApiCall",
    "managementEvent": true,
    "recipientAccountId": "123456789012",
    "eventCategory": "Management",
    "tlsDetails": {
        "tlsVersion": "TLSv1.3",
        "cipherSuite": "TLS_AES_256_GCM_SHA384",
        "clientProvidedHostHeader": "kms.eu-west-1.amazonaws.com"
    },
    "sessionCredentialFromConsole": "true"
}
```

------
#### [ GenerateDataKey ]

When you use a AWS KMS customer managed key to encrypt your [filter criteria](invocation-eventfiltering.md#filter-criteria-encryption) object in a `CreateEventSourceMapping` or `UpdateEventSourceMapping` call, Lambda sends a `GenerateDataKey` request on your behalf to generate a data key to encrypt the filter criteria ([envelope encryption](https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#enveloping)). The following example event records the `GenerateDataKey` operation:

```
{
    "eventVersion": "1.09",
    "userIdentity": {
        "type": "AssumedRole",
        "principalId": "AROA123456789EXAMPLE:example",
        "arn": "arn:aws:sts::123456789012:assumed-role/role-name/example",
        "accountId": "123456789012",
        "accessKeyId": "ASIAIOSFODNN7EXAMPLE",
        "sessionContext": {
            "sessionIssuer": {
                "type": "Role",
                "principalId": "AROA123456789EXAMPLE",
                "arn": "arn:aws:iam::123456789012:role/role-name",
                "accountId": "123456789012",
                "userName": "role-name"
            },
            "attributes": {
                "creationDate": "2024-05-30T00:06:07Z",
                "mfaAuthenticated": "false"
            }
        },
        "invokedBy": "lambda.amazonaws.com"
    },
    "eventTime": "2024-05-30T01:04:18Z",
    "eventSource": "kms.amazonaws.com",
    "eventName": "GenerateDataKey",
    "awsRegion": "eu-west-1",
    "sourceIPAddress": "lambda.amazonaws.com",
    "userAgent": "lambda.amazonaws.com",
    "requestParameters": {
        "numberOfBytes": 32,
        "keyId": "arn:aws:kms:eu-west-1:123456789012:key/a1b2c3d4-5678-90ab-cdef-EXAMPLE11111",
        "encryptionContext": {
            "aws-crypto-public-key": "ABCD+7876787678+CDEFGHIJKL/888666888999888555444111555222888333111==",
            "aws:lambda:EventSourceArn": "arn:aws:sqs:eu-west-1:123456789012:sample-source",
            "aws:lambda:FunctionArn": "arn:aws:lambda:eu-west-1:123456789012:function:sample-function"
        },
    },
    "responseElements": null,
    "requestID": "a1b2c3d4-5678-90ab-cdef-EXAMPLEaaaaa",
    "eventID": "a1b2c3d4-5678-90ab-cdef-EXAMPLEbbbbb",
    "readOnly": true,
    "resources": [
        {
            "accountId": "AWS Internal",
            "type": "AWS::KMS::Key",
            "ARN": "arn:aws:kms:eu-west-1:123456789012:key/a1b2c3d4-5678-90ab-cdef-EXAMPLE11111"
        }
    ],
    "eventType": "AwsApiCall",
    "managementEvent": true,
    "recipientAccountId": "123456789012",
    "eventCategory": "Management"
}
```

------