Danni-Tech

Making the Complicated Simple

Security Plus PKI - ASYMMETRIC ENCRYPTION

  • Key Points from This Video on Asymmetric Encryption:

    • What is Encryption?

      • Encryption ensures confidentiality, meaning only the intended party can access and read the data.
      • The process involves converting plaintext (e.g., “friend”) into ciphertext using an encryption algorithm, which can then be decrypted back to plaintext using a decryption algorithm.

    • Why Key-Based Encryption is Important:

      • Basic encryption is not secure enough because anyone with access to the algorithm could decrypt the data.
      • Key-based encryption introduces a secret key, ensuring only those with the correct key can decrypt the ciphertext.

    • Types of Key-Based Encryption:

      1. Symmetric Encryption: Uses the same key for encryption and decryption.
      2. Asymmetric Encryption: Uses different keys for encryption and decryption (covered in this video).

    • How Asymmetric Encryption Works:

      • Asymmetric encryption uses a pair of keys: one for encryption and a mathematically related key for decryption.
      • Example:
        • Encrypting the word “friend” with key 7 (shifting letters forward):
          • F → M
          • R → Y
          • I → P
          • E → L
          • N → U
          • D → K
        • Resulting ciphertext: “MYPLUK”
        • Decrypting with the related key 19 (shifting letters backward) restores the original word: “FRIEND”.

    • Trapdoor Functions:

      • Asymmetric encryption relies on trapdoor functions, which are easy to compute in one direction but difficult to reverse without the specific key.

    • Mathematically Related Keys:

      • The encryption and decryption keys are mathematically related.
      • Example:
        • Encrypt with 7, decrypt with 19
        • Encrypt with 5, decrypt with 21
        • Encrypt with 11, decrypt with 15
      • In these examples, the keys add up to 26 (the total number of letters in the alphabet), completing a full cycle.

    • Public and Private Keys:

      • Asymmetric encryption uses a public key (shared with others) and a private key (kept secret).
      • Data encrypted with the public key can only be decrypted with the private key, ensuring security even if the encrypted data is intercepted.

    • Pros and Cons of Asymmetric Encryption:

      • Advantages:
        1. Higher security since the private key is never shared.
        2. Ideal for securing communications, digital signatures, and encrypting session keys.
      • Drawbacks:
        1. Slower than symmetric encryption due to complex mathematical operations and larger key sizes.
        2. Ciphertext expansion occurs, meaning the encrypted data is larger than the original plaintext, which can affect bandwidth and transmission times.

    • Common Asymmetric Encryption Algorithms and Key Sizes:

      1. DSA (Digital Signature Algorithm): 2048-bit key
      2. RSA (Rivest-Shamir-Adleman): 2048-bit key
      3. Diffie-Hellman: 2048-bit key
      4. ECDSA (Elliptic Curve Digital Signature Algorithm): 256-bit key
      5. ECDH (Elliptic Curve Diffie-Hellman): 256-bit key

    • Key Takeaways:

      • Asymmetric encryption uses larger key sizes than symmetric encryption, which increases the load on the CPU.
      • It’s best suited for small amounts of data that require high security.