Are all 3 versions of AWS Server Side Encryption (SSE-S3, SSE-KMS, SSE-C) considered envelope encryption? In other words all 3 use 2 keys (one key to encrypt the data and is stored with the data and another key which is used to encrypted the data key)? Looking through the AWS docs I can't seem to conclude that all 3 versions of SSE are always envelope encryption.
No, only the first two versions of AWS SSE (SSE-S3 and SSE-KMS) use two keys. The third version, SSE-C, uses a single key.
SSE-C does not consider envelope encryption. SSE-C is a server-side encryption service offered by Amazon Web Services (AWS) that provides encryption of data stored in Amazon S3 buckets. It uses the Advanced Encryption Standard (AES) algorithm in Galois Counter Mode (GCM) to encrypt data.
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I have recently been reading about Amazon KMS, including envelope encryption. The source I used for envelope encryption (Free Code Camp) seems to consider 4 levels of envelope encryption (data encryption key, key encryption key, KMS master key and root KMS master key), as shown in the figure below:
On the other hand, what I have read in aws only seems to consider two levels (KMS key or key encryption key and data encryption key), as shown in the figure below:
Am I missing something here? Is this disparity only apparent?
Thanks in advance for your answers!
What you see here are just different levels of abstraction.
The upper diagram shows the whole chain of keys involved in creating data keys for encryption/decryption. It peeks under the hood of the KeyId abstraction.
The docs are quite extensive as cryptography is famously littered with pitfalls and edge cases, but here's my not entirely accurate but useful enough mental model of the process:
Through heavily-audited and secure random magic hardware appliances (HSMs) can come up with keys that (almost, except for replication) never leave the appliance. Besides creating these keys, HSMs can also encrypt and decrypt data using these keys as well as create more keys.
KMS exposes these HSMs in some ways to you. It allows you to manage these keys through the KMS API and create an abstraction called a master Key (there are different versions...) identified by a KeyId. This master key is not necessarily a single key (key material is what AWS uses in the docs).
Rather there are multiple keys under the hood, but they are not directly exposed to the user. The underlying keys can be rotated according to a schedule. Effectively this key is versioned, but only the most recent version is used to encrypt new data; older versions are only used to decrypt data.
The other keys in the chain in the diagram are pretty much just implementation details that you don't need to know unless you plan to audit KMS in which case my mental model won't be enough. In practice, the lower diagram is much more important.
The lower diagram shows what KMS looks like from a client that uses KMS to manage encryption keys to encrypt data in another system. To use KMS in a system, you only need to know the identifier of a KMS Key (KeyId) and have the appropriate permissions.
The flow looks like this for encryption:
You make a GenerateDataKey API Call to KMS and pass in the KeyId of the key you wish to use. KMS will then return (among other things) a plain text data key and an encrypted data key.
You use the plain text data key to encrypt your data locally and store the encrypted data alongside the encrypted data key. Next, you delete the plain text data key from memory.
For decryption the flow is as follows:
You read the encrypted data key from the encrypted object and make a call to the Decrypt API passing in the encrypted data key. Assuming you have permission, KMS will return the plain text data key [1][2].
You use the plain text data key to decrypt your encrypted data.
From the client's perspective, all you need to know about the keys that KMS uses is the KeyId (by default, there are more advanced features like encryption contexts).
[1] for symmetric encryption, it can infer the correct KeyId from the metadata, but as a best practice, you should send the KeyId as well.
[2] AWS infers the correct key-material for decryption from metadata in the encrypted blob.
My use case is to store digital certificate (issued by some certificate authority) in AWS Cloud HSM. I know we can store private key that signs the certificate. But is it possible to store full digital certificate itself? Can someone please share the steps?
Unfortunately you cannot store digital certificate in CloudHSM device
Here are things what you can achieve with it
When you use an HSM from AWS CloudHSM, you can perform a variety of cryptographic tasks:
Generate, store, import, export, and manage cryptographic keys, including symmetric keys and asymmetric key pairs.
Use symmetric and asymmetric algorithms to encrypt and decrypt data.
Use cryptographic hash functions to compute message digests and hash-based message authentication codes (HMACs).
Cryptographically sign data (including code signing) and verify signatures.
Generate cryptographically secure random data.
Docs & fAQ for more reference
I am storing data in file in aws s3 and already enabled SSE. but i am curious to know is there a way to encrypt the data so when someone download the file so they cant see the content?? I am just new to AWS and it would be great if somw one give the input
Use the AWS Key Management Service (AWS KMS) to encrypt the data prior to uploading it to an Amazon S3 bucket. Then the data will remain encrypted until it's decrypted using the key. YOu can find an example here (for Java SDK)
https://github.com/awsdocs/aws-doc-sdk-examples/blob/main/javav2/example_code/s3/src/main/java/com/example/s3/KMSEncryptionExample.java
already enabled SSE.
SSE encrypts the content on S3, but an authenticated client cloud access the content in plain, the encryption is done under the hood and the client is unable to access the ciphertext (encrypted form)
You can use the default s3 key or a custom KMS key (CMS) , where the client need explicit access to decrypt the content.
download the file so they cant see the content??
Then the content needs to be encrypted before the upload. AWS provides some support for the client-side encryption but the client is free to implement its own encryption strategy and the key management.
To solve trouble with managing the keys on the client side, it's often more practical to stick with SSE and allow access to S3 or the used CMS (key) only to identities that must access the content.
I am reading AWS encrypt cli document from https://docs.aws.amazon.com/cli/latest/reference/kms/encrypt.html and https://docs.aws.amazon.com/cli/latest/reference/kms/decrypt.html. I found that I am able to encrypt/decrypt without creating a data key. When I read https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html, it says that I need to use KMS CMK to generate a data key which is used to encrypt my data.
So I am confused about whether I need a data key at all?
CMK is designed to encrypt/decrypt the data keys. Therefore, there is a limit of 4 KB on the amount of plaintext that can be encrypted in a direct call to the encrypt function. You can easily test this by passing in message larger than 4 KB.
These operations are designed to encrypt and decrypt data keys. They use an AWS KMS customer master key (CMK) in the encryption operations and they cannot accept more than 4 KB (4096 bytes) of data. Although you might use them to encrypt small amounts of data, such as a password or RSA key, they are not designed to encrypt application data.
You are likely using a default CMK that was created by another AWS service that uses KMS encryption.
Of course all encryption and decryption operations require a key. If you did not explicitly create one for your application, then you are using the current default key.
Ensure that KMS Customer Master Keys (CMKs) are used by your AWS services and resources instead of default KMS keys, in order to have full control over data encryption/decryption process and meet compliance requirements. A KMS default master key is used by an AWS service such as RDS, EBS, Lambda, Elastic Transcoder, Redshift, SES, SQS, CloudWatch, EFS, S3 or Workspaces when no other key is defined to encrypt a resource for that service. The default key cannot be modified to ensure its availability, durability and security. On the other side, a KMS Customer Master Key (CMK) provides the ability to create, rotate, disable, enable and audit the encryption key used to protect the data.
See https://www.cloudconformity.com/knowledge-base/aws/KMS/default-key-usage.html
I am developing a project which requires video file encryption. I am familiar with AWS S3 so I have decided to use the same. I found the link Reference Link
Which says we need to provide our encryption key to to encrypt the data and AWS takes care of the data writing and we can access the file again by passing the same encryption key.
I want to know from where should I generate the encryption key?
You're looking at the "customer-provided encryption keys" section. In that case, you provide the encryption key.
If you don't want to, or know how to, manage your own keys, you should use S3-managed encryption keys or (even better) KMS-managed encryption keys.
For even more safety, client-side encryption is nice.