BlackBerry

Exercise

Build an API that will provide basic encryption and decryption using the Cryptography API through the use of a SymmetricKey.

Complete the implementation of the encrypt method:
1. Create a new AES symmetric key using keyData.
2. Create a new EncryptorEngine and FormatterEngine using the newly created key.
3. Create a BlockEncryptor using the FormatterEngine.
4. Create a new Digest (SHA-1) and hash the data using the digest.
5. Encrypt the data and append the hash returning the ciphertext.
Complete the implementation of the decrypt method:
1. Create a new AES symmetric key using keyData.
2. Create a new DecryptorEngine and UnformatterEngine using the newly created key.
3. Create a BlockDecryptor using the UnformatterEngine.
4. Decrypt the data.
5. Create a new Digest (SHA-1) and hash the data using the digest.
6. Verify that the hash is correct and return the plaintext.

Note: You are required to import the net_rim_crypto.jar file into your project to access the Cryptography API.

In this exercise, you discovered the following things:

Go to the next exercise in “Security for BlackBerry Applications”, Advanced features of the cryptography API