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Hritik Raj
Hritik Raj

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🔐 AWS 141: Data Protection at Rest - Mastering AWS KMS for File Encryption

#aws #kms #encryption #100daysofcloud

AWS KMS

🛡️ Securing the Vault: Encrypting Data with AWS KMS

Hey Cloud Architects 👋

Welcome to Day 41 of the #100DaysOfCloud Challenge!
Today, we are focusing on Cloud Security. The Nautilus DevOps team is prioritizing data integrity, and our mission is to implement a robust encryption workflow using AWS Key Management Service (KMS). We are ensuring that sensitive files remain unreadable to unauthorized users, even if they gain access to the storage layer.

This task is part of my hands-on practice on the KodeKloud Engineer platform, which provides excellent real-world scenarios for mastering DevOps security.

🎯 Objective

  • Provision a symmetric KMS key named nautilus-KMS-Key.
  • Encrypt a sensitive file (SensitiveData.txt) located in the /root/ directory.
  • Base64 encode the resulting ciphertext and save it as EncryptedData.bin.
  • Verify the setup by successfully decrypting the file back to its original state.

💡 Why KMS is a Game Changer

AWS KMS (Key Management Service) allows you to create and manage cryptographic keys across AWS services and your applications. It uses FIPS 140-2 validated hardware security modules (HSMs) to protect your keys.

🔹 Key Concepts

  • Symmetric Encryption: Using a single 256-bit secret key for both encryption and decryption.
  • Ciphertext vs. Plaintext: Plaintext is your readable data; Ciphertext is the encrypted version that appears as gibberish to anyone without the key.
  • Base64 Encoding: This process converts binary data into an ASCII string format, ensuring the encrypted data doesn't get corrupted during transit or storage.

🛠️ Step-by-Step: Security Workflow

🔹 Phase A: Create the KMS Key

First, we generate the master key that will handle our cryptographic operations.

  • Key Type: Symmetric.
  • Alias: nautilus-KMS-Key.
  • Configuration: Ensure the IAM user has the necessary permissions to use this key for encryption and decryption.

🔹 Phase B: Encrypt and Encode

We use the AWS CLI to perform the encryption. The --plaintext flag requires the fileb:// prefix to handle the file as binary.

  1. Perform Encryption: 
   aws kms encrypt --key-id alias/nautilus-KMS-Key --plaintext fileb:///root/SensitiveData.txt --output text --query CiphertextBlob > /root/EncryptedData.bin
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Note: The output is redirected to EncryptedData.bin as requested.

🔹 Phase C: Verify via Decryption

To confirm the encryption worked correctly, we must be able to reverse it.

  1. Decrypt the File: 
aws kms decrypt --ciphertext-blob fileb:///root/EncryptedData.bin --output text --query Plaintext | base64 --decode
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  1. Comparison: If the output matches the content of SensitiveData.txt, the verification is successful.

✅ Verify Success

  • File Integrity: Check that /root/EncryptedData.bin exists.
  • Key Configuration: Ensure the nautilus-KMS-Key alias points to the correct Key ID.
  • Validation: The validation script will successfully decrypt the binary file using your created key.

📝 Key Takeaways

  • 🚀 Alias Usage: Referencing keys by an Alias (e.g., alias/nautilus-KMS-Key) is better practice than using hardcoded Key IDs.
  • 🛡️ Binary Input: Always use the fileb:// prefix in AWS CLI when dealing with file inputs for encryption to prevent encoding errors.
  • 📦 Security Layers: Encrypting data at the application or OS level provides an extra layer of defense beyond standard disk encryption.

🚫 Common Mistakes

  • Missing Alias Prefix: Forgetting to add alias/ before the key name in the CLI command.
  • Permission Issues: Not giving the proper Key Policy permissions to the user performing the encryption.
  • Encoding Errors: Failing to base64 decode the plaintext result during manual verification, which results in a garbled string.

🌟 Final Thoughts

Encryption is a pillar of the "Shared Responsibility Model." By implementing AWS KMS for sensitive files, you ensure that Nautilus's data remains protected against unauthorized access. This is a fundamental skill for any security-conscious DevOps Engineer.

🌟 Practice Like a Pro

If you want to practice these security tasks in a live environment, check out:
👉 KodeKloud Engineer - Practice Labs

🔗 Let’s Connect

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