> For the complete documentation index, see [llms.txt](https://qanchain.gitbook.io/qan/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://qanchain.gitbook.io/qan/quantum-proof-onchain/dilithium5.md).

# Dilithium5

### **1. Overview**

**Dilithium5** is a **NIST-standardized** (FIPS 204) post-quantum digital signature scheme based on **hard lattice problems**. As the highest security variant of the CRYSTALS-Dilithium family, it provides 256-bit security against quantum attacks while maintaining practical performance for blockchain use cases.

#### **Key Features**

* **NIST PQC Winner**: Selected as the primary standard for post-quantum signatures (2024).
* **Optimal Balance**: 256-bit quantum security with faster verification than RSA/ECDSA.
* **On-Chain Optimized**: Modified for QAN’s hybrid EVM (reduced key sizes via BLAKE3 hashing).

***

### **2. Technical Specifications**

#### **2.1 Algorithm Parameters**

| Parameter            | Dilithium5 Specification                  |
| -------------------- | ----------------------------------------- |
| **Security Level**   | 256-bit (NIST L5)                         |
| **Base Problem**     | Module-LWE + Module-SIS                   |
| **Signature Size**   | 4,592 bytes (compressed to 2.8 KB in QAN) |
| **Public Key Size**  | 1,312 bytes                               |
| **Private Key Size** | 2,560 bytes                               |

#### **2.2 Performance Benchmarks**

| Operation    | QAN Testnet (w/ Hardware Acceleration) |
| ------------ | -------------------------------------- |
| Verification | \~12 ms (*3x faster than RSA-4096*)    |

*Note: Benchmarked on QAN’s quantum-resistant VM with Intel SGX enclaves.*

***

### **3. QAN-Specific Optimizations**

#### **Key Size Compression**

QAN reduces Dilithium5’s native key sizes by:

* **BLAKE3 Hashing**: Compresses public keys from 1.3 KB → 0.9 KB.
* **Key Reuse**: Session-based ephemeral keys for smart contracts.

***

### **4. Comparative Analysis**

#### **4.1 vs. Classical Algorithms**

| Metric            | Dilithium5 | ECDSA (secp256k1) |
| ----------------- | ---------- | ----------------- |
| **Quantum-Safe?** | ✅ Yes      | ❌ No              |
| **Sig Verify**    | 12 ms      | 5 ms              |
| **Key Size**      | 1.3 KB     | 64 B              |

#### **4.2 vs. Other PQC Algorithms**

| Algorithm      | Security | Sig Size | Verification Speed |
| -------------- | -------- | -------- | ------------------ |
| **Dilithium5** | 256-bit  | 2.8 KB   | ⚡ 12 ms            |
| MLDSA-87       | 87-bit   | 2.5 KB   | ⚡ 10 ms            |
| Falcon-1024    | 256-bit  | 1.3 KB   | 🐢 38 ms           |

***

### **5. Use Cases in QAN**

* **High-Value Transactions**: Government, central bank digital currencies (CBDCs).
* **Smart Contract Oracles**: Tamper-proof data feeds with quantum-safe auth.
* **NFT Royalties**: Immutable signature chains for IP ownership.