Cryptvault

Allows for a versioned, secure generic crypt/decrypt in java.

Originally developed for spring-data-mongodb-encrypt, it is now offered as a general use library.

Features

• key versioning (to help migrating to new key without need to convert data)
• uses 256-bit AES by default
• supports any encryption available in Java (via JCE)
• simple
• no dependencies

Use

Add dependency:

<dependency>
    <groupId>com.bol</groupId>
    <artifactId>cryptvault</artifactId>
    <version>1.0.2</version>
</dependency>

And add the following to your application.yml:

cryptvault:
  keys:
    - version: 1
      key: hqHKBLV83LpCqzKpf8OvutbCs+O5wX5BPu3btWpEvXA=

And you're done!

Example usage:

@Autowired CryptVault cryptVault;

// encrypt
byte[] encrypted = cryptVault.encrypt("rock".getBytes());

// decrypt
byte[] decrypted = cryptVault.decrypt(encrypted);

new String(decrypted).equals("rock");   // true 

Manual configuration

You can also configure CryptVault yourself. Look at how spring autoconfig configures CryptVault for details.

Keys

This library supports AES 256 bit keys out of the box. It's possible to extend this, check the source code (CryptVault specifically) on how to do so.

To generate a key, you can use the following command line:

dd if=/dev/urandom bs=1 count=32 | base64

Exchange keys

It is advisable to rotate your keys every now and then. To do so, define a new key version in application.yml:

cryptvault:
  keys:
    - version: 1
      key: hqHKBLV83LpCqzKpf8OvutbCs+O5wX5BPu3btWpEvXA=
    - version: 2
      key: ge2L+MA9jLA8UiUJ4z5fUoK+Lgj2yddlL6EzYIBqb1Q=

spring-data-mongodb-encrypt would automatically use the highest versioned key for encryption by default, but supports decryption using any of the keys. This allows you to deploy a new key, and either let old data slowly get phased out, or run a nightly load+save batch job to force key migration. Once all old keys are phased out, you may remove the old key from the configuration.

You can use

cryptvault:
  default-key: 1

to override which version of the defined keys is considered 'default'.

Expected size of encrypted data

Depending on how much padding is used, you can expect 17..33 bytes for encryption overhead (salt + padding).