karanpal-dhillon / self-destruct-o

Serverless one-time password sharing app

Self-destruct-o

A serverless service for posting/retrieving secrets that self destruct from the backend on read.

Secrets are stored in DynamoDB with a 7 day TTL.

DynamoDB stores the data at rest encrypted via DynamoDB server side encryption.

Individual items are encrypted using envelope encryption with per-item encryption keys.

The master key is stored in AWS KMS and only accessible to the root AWS account, and the Lambda function that reads from DynamoDB.

Users can optionally provide a passphrase. When using a passphrase, an encryption key is derived from the passphrase using PBDKF2, and the secret is encrypted with AES-256 in CBC mode (in the browser) prior to being sent to the backend.

Installation

First, you need to provision a KMS key (which will cost you 1$/month)

Creating a KMS key:

aws kms create-key --region us-east-1 --description 'self-destruct-o'

Take note of that KSM key id.

Setup a SSM parameter for the key id:

aws ssm put-parameter --region us-east-1 \
--name "/self-destruct-o/kms-key-id" \
--value "YOURKEYIDHERE" --type SecureString

Setup dependancies

npm i serverless -g
npm i

Deploy the code to AWS. This will create a DynamoDB table, setup the API Gateway endpoint, upload the Lambda.

sls deploy -s dev --region us-east-1

This command should output the three API gateway endpoints. To hit the one with the UI, look for the GET endpoint that doesn't have a parameter.

Enjoy your newly created password sharing system.

Key management

To rotate the key, simply create a new key in KMS, and update the SSM parameter used by the Lambdas. Old secrets will still work as long as the KMS key is ok. Once you've updated SSM, schedule the old key to be deleted.