Encryption options for data at rest and data in transit

Can you explain the difference between symmetric and asymmetric encryption and when you would use each on AWS?

Symmetric encryption uses the same secret key for encryption and decryption. It is faster and is used when large amounts of data need to be processed quickly, such as Amazon S3 server-side encryption with Amazon S3-managed keys (SSE-S3) or AWS KMS-managed keys (SSE-KMS). Asymmetric encryption uses a pair of keys, a public key to encrypt data and a private key to decrypt it. It’s used in scenarios where secure key exchange is critical, such as establishing secure connections with AWS services using AWS KMS customer-managed keys.

In AWS, what is the difference between AWS KMS and CloudHSM and when would you opt for one over the other?

AWS KMS is a managed service that makes it easy for you to create and control encryption keys. KMS is integrated with other AWS services and supports both symmetric and asymmetric encryption. AWS CloudHSM provides dedicated hardware security modules within the AWS cloud, offering a higher level of security compliance for keys. You would opt for CloudHSM if you need FIPS 140-2 Level 3 compliance or if you have to manage your encryption keys in an isolated hardware security module.

How can you ensure data in transit is encrypted when connecting your on-premises environment to AWS?

You can ensure data in transit encryption by using AWS VPN connections which provide IPsec encrypted tunnels, or AWS Direct Connect in combination with VPN for secure communication. Alternatively, implementing TLS on application endpoints or using AWS Client VPN can also guarantee the encryption of data in transit.

What AWS service can you use to automatically encrypt objects before saving them to S3 and decrypt them when retrieving?

You can use Amazon S3 with server-side encryption (SSE) to automatically encrypt your objects before they are stored. When you retrieve the objects, S3 decrypts them for you. There are multiple SSE options, including SSE-S3 (using S3-managed keys), SSE-KMS (using AWS KMS keys), and SSE-C (using customer-provided keys).

How would you implement encryption at rest for an EBS volume attached to an EC2 instance?

You can implement encryption at rest for an Amazon EBS volume by enabling the encryption property when creating a new EBS volume. This volume will then be encrypted with an AWS KMS Customer Master Key (CMK). If the EBS volume is already created, you would need to create a snapshot and then copy the snapshot with encryption enabled, and finally create a new EBS volume from the encrypted snapshot.

What considerations might you have when rotating encryption keys in AWS?

When rotating encryption keys in AWS, one must consider the potential impact of key rotation on data accessibility and whether any services will require re-encryption with the new key. For keys managed by AWS KMS, automatic key rotation can be enabled. However, for customer-managed keys, you’ll need to have a manual process in place. It’s also important to consider the key rotation policy and to ensure that older keys remain accessible for decryption purposes to prevent data lockout.

How can you protect against unauthorized access when managing encryption keys in AWS KMS?

In AWS KMS, you can protect against unauthorized access by setting key policies and IAM policies that define who can use the key and under what conditions. Additionally, you can use features like multi-factor authentication (MFA) for sensitive operations, as well as audits using CloudTrail to log the use of keys.

If your company has a compliance requirement that all data in transit has to be encrypted, how can you enforce this for access to the AWS Management Console and your application APIs hosted on AWS?

For the AWS Management Console, you can enforce HTTPS connections by default. Regarding application APIs, you can configure your application load balancers, API Gateway, or CloudFront distributions to only allow HTTPS connections with properly configured SSL/TLS certificates, and enforce HSTS (HTTP Strict Transport Security) policy to ensure clients use only secure connections.

What is the role of AWS Certificate Manager (ACM) in encryption on AWS?

AWS Certificate Manager (ACM) is a service that lets you easily provision, manage, and deploy public and private SSL/TLS certificates for use with AWS services and your internal connected resources. Certificates provided by ACM are used to encrypt data in transit via HTTPS (TLS/SSL) on supported AWS resources like Load Balancers, CloudFront distributions, and API Gateway.

How does Amazon RDS provide encryption for its databases and what are your options for enabling it?

Amazon RDS provides encryption at rest by using AWS KMS to manage the database encryption keys. To enable encryption, you must specify this option upon the creation of a new RDS instance or snapshot. RDS supports encrypted instances for MySQL, PostgreSQL, MariaDB, Oracle, and SQL Server. Existing unencrypted RDS instances cannot be directly encrypted; instead, you would need to create an encrypted snapshot and restore from that snapshot to an encrypted instance.