110.3 Securing data with

Tech Tutorial: 110.3 Securing Data with Public Key Techniques #

Introduction #

In the realm of IT security, safeguarding data and communication is paramount. One of the most effective ways to achieve this is through the use of public key techniques, also known as asymmetric cryptography. This tutorial will guide you through the basics of using these techniques to secure data and communications on Linux systems.

Key Knowledge Areas: #

  • Understanding public and private keys
  • Generating key pairs
  • Encrypting and decrypting data
  • Signing and verifying data
  • SSH for secure remote communication

Utilities: #

  • gpg (GNU Privacy Guard)
  • ssh (Secure Shell)
  • openssl

Step-by-Step Guide #

1. Understanding Public and Private Keys #

In asymmetric cryptography, two keys are used: a public key and a private key. The public key can be shared with anyone, while the private key must be kept secure and private. Data encrypted with the public key can only be decrypted with the private key, and vice versa.

2. Generating Key Pairs #

Using GPG #

# Generate a new GPG key pair
gpg --full-generate-key

# List the generated keys
gpg --list-keys

# Export the public key
gpg --export -a "Your Name" > public.key

# Export the private key
gpg --export-secret-keys -a "Your Name" > private.key

Using OpenSSL #

# Generate a private key
openssl genrsa -out private.pem 2048

# Extract the public key
openssl rsa -in private.pem -outform PEM -pubout -out public.pem

3. Encrypting and Decrypting Data #

Using GPG #

# Encrypt a file using the public key
gpg --encrypt --recipient 'Your Name' -o encrypted_file.gpg file_to_encrypt.txt

# Decrypt the file using the private key
gpg --decrypt -o decrypted_file.txt encrypted_file.gpg

Using OpenSSL #

# Encrypt a file using the public key
openssl rsautl -encrypt -inkey public.pem -pubin -in file_to_encrypt.txt -out encrypted_file.ssl

# Decrypt the file using the private key
openssl rsautl -decrypt -inkey private.pem -in encrypted_file.ssl -out decrypted_file.txt

4. Signing and Verifying Data #

Using GPG #

# Sign a file
gpg --sign -o signed_file.gpg file_to_sign.txt

# Verify the signature
gpg --verify signed_file.gpg

Using OpenSSL #

# Generate a signature
openssl dgst -sha256 -sign private.pem -out signature.bin file_to_sign.txt

# Verify the signature
openssl dgst -sha256 -verify public.pem -signature signature.bin file_to_sign.txt

5. SSH for Secure Remote Communication #

# Generate SSH key pair
ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

# Copy the public key to the remote server
ssh-copy-id -i ~/.ssh/id_rsa.pub user@remote_host

# Connect to the remote server securely
ssh user@remote_host

Detailed Code Examples #

In the sections above, we’ve provided multiple examples for each utility and operation. These examples are ready to be used in real-world scenarios, providing a robust foundation for securing data and communication.

Conclusion #

By mastering the use of public key techniques, you can significantly enhance the security of data and communications. Whether you’re encrypting files, verifying signatures, or securing remote SSH access, the utilities and examples provided in this tutorial will help you implement strong security practices on Linux systems.