Notes to Self

Alex Sokolsky's Notes on Computers and Programming

Credstash

https://github.com/fugue/credstash or https://github.com/LuminalOSS/credstash

Installation

Client installation:

pip install credstash

Use

Full Example

Store private file asokolsky_kp.pem, retrieve it, delete secret:

credstash setup
credstash put asokolsky_kp @asokolsky_kp.pem
credstash get asokolsky_kp
credstash delete asokolsky_kp

Adding secrets

Make a global secret. Will not overwrite the existing secret! See the repo README about versioning secrets.

credstash put <secret-name> <secret-data>

Reading secrets

This will print to STDOUT.

credstash get <secret-name>

You can also use encryption contexts to limit/modify access.

Giving access

If user/app needs to be able to encrypt/decrypt, they need to be given key usage rights to the ‘credstash’ IAM master key. A user (and never a production app!) only needs key admin rights if they need to be able to add users, revoke and regenerate the key, etc. For read access, the credstash-read-secrets IAM role is needed. For secret creation access, use the credstash-write-secrets IAM role.

Separating secrets

By default, the ‘credstash’ KMS key and the ‘credential-store’ DynamoDB table are used for access and storing secrets. You can create additional keys and tables to allow separation and compartmentalization of secrets. For example, creating a ‘credstash-prod’ KMS key and ‘production-credentials’ table and giving rights (through instance roles) to applications on production instances that need to get keys, etc.

You can also use encryption contexts to limit/modify access.

Basic Architecture

AWS KMS provides the secure encryption key management.

Encrypted items are stored in the AWS DynamoDB table credential-store. We can create additional tables for access separation.

Caveats

The data to be encrypted must be less than 4096 bytes, because of the size of the KMS key. If the data is larger, you can always encrypt a larger encryption key and deliver the actual data already encrypted with that.

Secrets are “global” to all org users with credstash IAM key usage rights unless they are created with encryption contexts. However, you can use different DynamoDB tables for different credentials, and limit access to those with different policies.

Current AWS IAM policies

credstash-read-secrets - read only, uses default credstash DDB table ‘credential-store’

credstash-write-secrets - write only, uses default credstash DDB table ‘credential-store’