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Exhibit 2 of 23
Hall 1 · Exhibit 2 1 min

Symmetric vs. Asymmetric Encryption

Two families that protect the internet together

Two familiesSymmetric (one key) · Asymmetric (key pair)
Symmetric champAES — fast, ideal for bulk data
Asymmetric champsRSA · ECC · Diffie–Hellman
How the web uses bothHybrid handshake — asym exchange, sym data

Symmetric Encryption (Same Key)

Both sender and receiver use the same secret key to lock and unlock data. The champion algorithm is AES (Advanced Encryption Standard), used by the U.S. government for Top Secret data. AES is blazing fast — modern CPUs have dedicated hardware to run it instantly — making it ideal for encrypting data at rest (hard drives) and high-volume data in transit (streaming video).

Other notable symmetric ciphers include Twofish and Blowfish, used for disk encryption and high-performance applications. The fatal flaw: how do you share the key with a stranger over an open network?

Asymmetric Encryption (Two Keys)

Each user generates a mathematically linked pair: a Public Key (shared openly, used only to encrypt) and a Private Key (kept secret, used only to decrypt). Data encrypted with the Public Key can only be decrypted by the corresponding Private Key — even the Public Key itself cannot unscramble what it created.

The champion algorithms are , (Elliptic Curve Cryptography), and Diffie-Hellman (used for secure key exchanges over insecure channels). The flaw: asymmetric math is complex and slow.

The Hybrid Handshake

Every time you visit an HTTPS website, your browser performs a hybrid handshake: it uses slow asymmetric encryption (/) to securely exchange a temporary symmetric key, then switches to fast symmetric encryption (AES) for the rest of the session. This gives you the security of asymmetric key exchange with the speed of symmetric data encryption.

Symmetric vs. asymmetric encryptionSYMMETRICAES · ChaCha20Aliceshared keyBobshared key (same)ciphertextProblem: how do they share the key?ASYMMETRICRSA · ECC · ML-KEMAliceprivate keyBobAlice's public keyencrypted with public keySolves: public key is shared openly.
Symmetric solves speed; asymmetric solves key distribution. The internet uses both.

This hybrid approach — asymmetric for key exchange, symmetric for bulk data — is the foundation of all internet security and is directly relevant to understanding PQC migration.

Key Takeaways

  • Symmetric encryption uses one shared key — fast but has a key-distribution problem
  • Asymmetric encryption uses a key pair — solves distribution but is slow
  • The hybrid handshake combines both: asymmetric for key exchange, symmetric for data