Danni-Tech

Making the Complicated Simple

Security Plus PKI - PUBLIC/PRIVATE KEYS

  • Key Points from This Video on Public and Private Keys 

    • Introduction to Asymmetric Encryption:

      • Asymmetric encryption uses a key pair: one public key and one private key.
      • These keys are mathematically related—one key encrypts data, and the other decrypts it.

    • Encryption Example (John and Susie):

      1. John wants to send a secure message to Susie.
      2. John encrypts the message using Susie’s public key.
      3. Susie decrypts the message using her private key.
      • Key Point: Once data is encrypted with Susie’s public key, only her private key can decrypt it, ensuring confidentiality.

    • Message Signatures Example:

      • Purpose: To prove the authenticity of a message, not necessarily to secure it.
      1. John signs a message using his private key.
      2. He sends the signed message to Susie.
      3. Susie verifies the signature using John’s public key.
      • This process proves:
        • Authentication: The message came from John because only he controls his private key.
        • Integrity: The message wasn’t altered in transit because the signature verification succeeded.

    • Challenges with Asymmetric Encryption:

      • Not ideal for large data sets due to slower processing speeds.
      • Key Problem: How to securely exchange symmetric keys for bulk data encryption.

    • Hybrid Encryption:

      • Definition: A combination of asymmetric and symmetric encryption.
      • How It Works:
        1. John generates a symmetric secret key (random bits of 1s and 0s).
        2. He encrypts this symmetric key using Susie’s public key.
        3. Susie decrypts the symmetric key using her private key.
        4. Both John and Susie now share the symmetric key for encrypting and decrypting bulk data.
      • Real-World Use: Commonly used in SSL/TLS to secure data in transit.

    • Digital Signatures:

      • Purpose: To provide authentication, data integrity, and non-repudiation.
      • Process:
        1. Susie uses a hashing algorithm to generate a digest of her message.
        2. She signs the digest with her private key, creating a digital signature.
        3. John receives the message and verifies the signature using Susie’s public key.
        4. John also hashes the received message to generate a digest.
        5. If both digests match:
          • Integrity: The message wasn’t altered in transit.
          • Authentication: The signature proves the message came from Susie, as only she holds the private key.
          • Non-Repudiation: Susie cannot deny having sent the message because the signature can only be created with her private key, which is uniquely tied to her.

    • Key Takeaways:

      1. Public Key: Shared openly, used to encrypt data or verify signatures.
      2. Private Key: Kept secret, used to decrypt data or create signatures.
      3. Hybrid Encryption: Combines the strengths of symmetric and asymmetric encryption for secure key exchange and efficient data encryption.
      4. Digital Signatures: Ensure authentication, integrity, and non-repudiation—proving who sent the message, that it hasn’t been altered, and that the sender cannot deny their involvement.