9.1. Filtering, Validating, and Sanitizing User Input9.2. Keeping Sensitive Credentials Out of Application Code9.3. Hashing and Validating Passwords9.4. Encrypting and Decrypting Data9.5. Storing Encrypted Data in a File9.6. Cryptographically Signing a Message to Be Sent to Another Application9.7. Verifying a Cryptographic Signature