Is it possible to get files from encrypted S3 buckets using boto 2? I am working with a project that uses S3 in several places and has to read/write to an encrypted S3 bucket. I would like to make as small a change as possible, for the time being, to support encryption.
Encryption actually works at the object level, rather than the bucket.
There are several ways to use encryption. If it is Protecting Data Using Server-Side Encryption with Amazon S3-Managed Encryption Keys (SSE-S3), then as long as your app has permission to access the object then it will be automatically decrypted. (The app won't even notice that it was encrypted!)
If it is Protecting Data Using Server-Side Encryption with AWS KMS–Managed Keys (SSE-KMS), the app will also need adequate permissions to use the key in KMS. The object will be automatically decrypted, but it needs permissions to use the key.
If the app is Protecting Data Using Server-Side Encryption with Customer-Provided Encryption Keys (SSE-C), then the app must provide the encryption key when it tries to access the object.
And finally, if it is Protecting Data Using Client-Side Encryption, then the app is totally responsible for encryption/decryption.
It is most likely that your data is using Server-Side Encryption with Amazon S3-Managed Encryption Keys (SSE-S3). If so, then your app doesn't have to do anything — it will all be handled automagically by Amazon S3.
Related
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.
When I SSE-S3 encrypt the bucket (objects) with AES256 and make it public. The contents of the bucket are visible. However, this is not the case with AWS KMS which throws the following error:
Requests specifying Server Side Encryption with AWS KMS managed keys require AWS Signature Version 4.
How is the end-user able to view the object in AES256 encrypted?
Use Server-Side Encryption with Amazon S3-Managed Keys (SSE-S3) – Each
object is encrypted with a unique key employing strong multi-factor
encryption. As an additional safeguard, it encrypts the key itself
with a master key that it regularly rotates. Amazon S3 server-side
encryption uses one of the strongest block ciphers available, 256-bit
Advanced Encryption Standard (AES-256), to encrypt your data.
According to this, my understanding is, if an object is encrypted it requires the decryption keys or in AWS world access to the key that is decrypting it. Please explain how AES256 is different from KMS. (Other than key policies provided by AWS on KMS)
Server-Side Encryption in S3 is always AES256, whether you are using SSE-S3 or SSE-KMS.
In both cases, S3 uses a key to transparently encrypt the object for storage and decrypt the object on request. The user accessing the object does not see the encrypted object in either case.
With SSE-S3, S3 owns and controls the keys, so permission to upload or download includes implicit permission for S3 to access the keys that it needs in order to access the object.
The level of encryption is the same whether you use SSE-S3 or SSE-KMS, but SSE-KMS imposes more stringent security constraints on accessing the objects, including mandatory use of HTTPS and Signature Version 4.
Say for example I leave an AWS S3 bucket open to the public.
My goal is that if someone downloads a file from that bucket then what they get is an encrypted file.
I thought SSE-S3 would do this but it does not - it appears that any file downloaded is not encrypted.
So how can I reach my goal of ensuring that files served from S3 are encrypted?
What you are looking for is Protecting Data Using Client-Side Encryption. If you want S3 to serve encrypted files, then you have to save them as encrypted object. You manage encryption/decryption. SSE will store the data after encrypting it and will decrypt it automatically when it is downloaded.
From: Protecting Data Using Encryption
Use Server-Side Encryption – You request Amazon S3 to encrypt your object before saving it on disks in its data centers and decrypt it when you download the objects.
Use Client-Side Encryption – You can encrypt data client-side and upload the encrypted data to Amazon S3. In this case, you manage the encryption process, the encryption keys, and related tools.
I'm trying to use server side encryption having AWS KMS setup to upload objects to S3.
The documentation says that the uploaded objects should be encrypted;
Server-side encryption is about data encryption at rest—that is,
Amazon S3 encrypts your data at the object level as it writes it to
disks in its data centers and decrypts it for you when you access it.
I've setup KMS master key and trying to use CLI to upload an object in the following way
aws s3api put-object --bucket test --key keys/test.txt --server-side-encryption aws:kms --ssekms-key-id <my_master_Key_id> --body test.txt
The upload succeeds and I see the following response
{
"SSEKMSKeyId": "arn:aws:kms:eu-central-1:<id>:key/<my_master_key>",
"ETag": "\"a4f4fdf078bdd5df758bf81b2d9bc94d\"",
"ServerSideEncryption": "aws:kms"
}
Also when checking the file in S3 I see in details that it has been encrypted server side with a proper master key.
The problem is that when I download the file with a user not having a permission to use the KMS master key, I can open and read the file without a problem, when it should be encrypted.
Note: I also have PutObject policy denying all uploads without server-side encryption, which works fine.
I wonder if I misunderstand the server side encryption, or do I do something wrong? Any help is appreciated.
Unfortunately, I think you misunderstood server-side encryption in S3. Like you pointed yourself, from S3 server-side encryption (SSE) docs:
Server-side encryption is about protecting data at rest.
When S3 receives your object, it calls KMS to create a data key, encrypts your data with that data key (not the master key), and stores the encrypted data key along with the encrypted data.
When you try to download the encrypted files, S3 sees it has been encrypted, asks KMS to decrypt the data key (using the master key), and then uses the decrypted data key to decrypt the data before returning to you. My understanding from the docs and from the way SSE and KMS work is that there is no assumption on the user needing to have access to the master key for that to work -- it suffices that S3 has access to it.
The use case you described is more similar to S3 client-side encryption:
Client-side encryption refers to encrypting data before sending it to
Amazon S3.
In this scenario, the S3 client (instead of S3 on the backend) will ask for a KMS data key (derived from the master key), encrypt data client-side and upload it. It will not be possible to decrypt it on the server, and when clients download the (encrypted) files, decryption needs to happen client-side (the S3 client deals with that for you, though).
Has anybody tried to use AWS KMS on Heroku?
On one hand, Heroku runs on AWS, so presumably it should work.
On other hand, I haven't seen any references that it was used in Heroku.
My main goal is to be able to get an encryption key from a hardware secure module (vs hardcoding it in my code or putting it in an environmental variable).
There is no reason why you should not be able to call a KMS endpoint from anywhere you have internet connectivity.
You still need to have an access key and secret access key for the AWS account you are using and that account needs to have permissions on KMS.
You will need to distribute the encrypted stuff and the aws keys to your Heroku instance. You can then decrypt and use KMS from there.
One thing that it worth mentioning: when using KMS you never see the actual key KMS uses. You can create the key, you can encrypt and decrypt, and/or you can have permissions on the specific API operations, but you cannot get the plaintext key.
What you normally do is some sort of envelope encryption in which you generate your own key and encrypt it via KMS and send the encrypted key and the encrypted data to the destination.