🧱 The Building Blocks
Cipher Layers Explained
In 5 minutes: Understanding what a cipher layer is
Prerequisite: None
🎯 The Simple Story
Imagine you have a Lego building set.
Lego Blocks:
🧱 Red brick
🧱 Blue brick
🧱 Green brick
🧱 Yellow brick
🧱 Purple brick
Each brick is different but all are Lego bricks.
You can combine them in any order to build anything!
Cipher layers are like Lego blocks:
Cipher Layers (Building Blocks):
🔐 AES Layer (Password encryption)
🤝 DH Layer (Key exchange handshakes)
📞 Signal Layer (2-person encryption)
🚪 MLS Layer (Group encryption)
🔒 ML-KEM Layer (Quantum-resistant encryption)
Each layer encrypts differently but all are cipher layers!
You can combine them in any order to build your encryption!
🧠 Mental Model
Hold this picture in your head:
Cipher Layer = Building Block
Layer definition:
1. Has a name: "AES Layer", "DH Layer", etc.
2. Has a version: "1.0.0", "2.0.0", etc.
3. Has a job: encrypt → decrypt
4. Accepts keys/parameters
5. Returns encrypted data with metadata
Layers work in isolation:
- Layer 1 doesn't care about Layer 2
- Layer 2 doesn't care about Layer 3
- Each does its own job
- Combined result = layered encryption
Like building blocks:
CascadingCipherManager:
┌─────────────────────────────┐
│ 🧱 CipherLayer Interface │
│ │
│ "To be a cipher layer:" │
│ 1. Have a name │
│ 2. Have a version │
│ 3. Implement encrypt() │
│ 4. Implement decrypt() │
│ 5. Validate keys() │
└─────────────────────────────┘
Different Layer Implementations:
┌─────────────────┐
│ AES CipherLayer │ ← Implements
│ - encrypt() │ CipherLayer
│ - decrypt() │ Interface
└─────────────────┘
┌─────────────────┐
│ DH CipherLayer │ ← Implements
│ - encrypt() │ CipherLayer
│ - decrypt() │ Interface
└─────────────────┘
┌─────────────────┐
│ Signal CipherLayer│ ← Implements
│ - encrypt() │ CipherLayer
│ - decrypt() │ Interface
└─────────────────┘
Think of it like:
🧱 Standard Lego bricks
- All are Lego (same interface)
- Different colors/sizes (different implementations)
- Can build anything with any bricks
- Each brick does one thing
📊 How Cipher Layers Work
Layer Isolation
Each cipher layer is independent:
AES Cipher Layer:
├─ Only knows how to: encrypt/decrypt with AES
├─ Doesn't care about: Signal
└─ Doesn't care about: MLS
Signal Cipher Layer:
├─ Only knows how to: encrypt/decrypt with Signal
├─ Doesn't care about: AES
└─ Doesn't care about: MLS
MLS Cipher Layer:
├─ Only knows how to: encrypt/decrypt with MLS
├─ Doesn't care about: AES
└─ Doesn't care about: Signal
Result: Layers are independent building blocks!
The Interface
Every cipher layer implements the same interface:
interface CipherLayer {
// Layer identity
name: string; // e.g., "AES-GCM-256"
version: string; // e.g., "1.0.0"
// Layer job
encrypt(data, keys); // Turn plaintext → ciphertext
decrypt(payload, keys); // Turn ciphertext → plaintext
// Validation
validateKeys(keys); // Check keys are good
}
This is key: All layers have the same interface! The manager can use any layer the same way!
🎭 The Story: Building Your Encryption Castle
Alice wants to build a secure castle (encryption system) to protect her treasure (messages).
Step 1: Pick Your Blocks
Alice has 5 cipher layer blocks:
1. AES Block (safe deposit box)
2. DH Block (handshake)
3. Signal Block (phone booth)
4. MLS Block (meeting room)
5. ML-KEM Block (magic lockbox)
Each block can protect your treasure differently.
Step 2: Stack Your Blocks
Day 1: Alice uses just AES Block
├─ Simple
├─ Fast
└─ Problem: Eve breaks AES → Game over!
Day 30: Alice adds Signal Block on top
├─ Still fast-ish
├─ Now has 2 layers
└─ Eve breaks AES → Still needs Signal!
Day 60: Alice adds MLS Block
├─ Now has 3 layers
├─ Eve: Broke AES... still need Signal + MLS!
└─ Getting harder!
Day 90: Alice adds DH + ML-KEM Blocks
├─ Now has 5 layers
├─ Eve: Broke AES + Signal + DH...
└─ Still needs MLS + ML-KEM!
Eve: "Why is this so hard?"
Alice: "Because I layered my protection!"
Step 3: Independence Matters
What if there's a bug in Signal Block?
Alice's castle:
┌───────────────────────────┐
│ MLS Block │ ← Still works!
│ ← Broken Signal Block │ ← Has bug!
│ ← DH Block │ ← Still works!
│ ← AES Block (broken too)│ ← Had vulnerability
└───────────────────────────┘
AES and Signal vulnerable but:
- Eve needs to break 3 MORE layers
- MLS, DH, ML-KEM still work
- Alice's treasure still safe!
This is the power of: Layer independence
🎮 Try It Yourself
Question 1: What does "layer independence" mean?
Show Answer
Layer independence means each cipher layer works independently. The AES layer doesn't care about the Signal layer. The Signal layer doesn't care about the MLS layer. Even if one layer has a bug or gets broken, the other layers continue to work and protect your data.
Question 2: Why implement a common interface for all cipher layers?
Show Answer This
Because of the "building block" design principle! If all layers implement the same CipherLayer interface, the CascadingCipherManager can use any layer without needing to know the details. It's like using any Lego brick to build anything - you don't need special tools for each different brick.
Question 3: True or False: If AES has a vulnerability, all layers in a cascading cipher are vulnerable.
Show Answer This
False! Because layers are independent, a vulnerability in AES doesn't affect DH, Signal, MLS, or ML-KEM. Eve would need to break AES AND the other layers to get your data. One layer compromised doesn't mean all layers are compromised.
💡 Why This Matters
Real-World Example: The TLS 1.3 Update
Old TLS (single layer):
Connection: TLS 1.2
└─ Uses: RSA + AES-GCM
└─ Problem: Quantum computers break both!
Result: Entire protocol needs replacement
New TLS 1.3 (can use cascading):
Connection: TLS 1.3
└─ Uses: Multiple cipher suites
├─ AES-GCM-256-SHA384 (future quantum-safe alternative)
├─ X25519 key exchange
└─ Optional: Post-quantum layer (still being standardized)
Result: Can transition to quantum-safe algorithms without breaking everything!
✅ Quick Check
Can you explain cipher layers to a 5-year-old?
Try saying this out loud:
"Cipher layers are like Lego blocks. Each brick is called a 'cipher layer'. There are red bricks, blue bricks, green bricks - but they're all Lego! You use different bricks to build different things. You can put a red brick on top of a blue brick on top of a green brick to build a tall tower. If someone takes one brick away, the tower still has other bricks holding it up!"
🎓 Key Takeaways
✅ Cipher Layer = Building block for encryption
✅ Common Interface = All layers look the same to manager
✅ Layer Independence = One broken doesn't break others
✅ Composability = Combine layers in any order
✅ Extensibility = Easy to add new layer types
Now you understand what cipher layers are. Next: How they cascade together!