> For the complete documentation index, see [llms.txt](https://cryptic-documentation.gitbook.io/cryptic-pq/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cryptic-documentation.gitbook.io/cryptic-pq/crytic-enterprise-whitepaper/6.-use-cases.md).

# 6. Use Cases

#### 6.1 Blockchain & Web3

{% @mermaid/diagram content="sequenceDiagram
participant User as Web3 User
participant Wallet as Wallet App
participant Cryptic as Cryptic API
participant Blockchain as Blockchain Network

```
Note over User,Blockchain: Initial Setup
User->>Wallet: Connect wallet
Wallet->>User: Sign auth message (ECDSA)
User->>Cryptic: POST /keys/dilithium3/generate<br/>Auth: Chain Signature
Cryptic->>Cryptic: Verify signature, extract address
Cryptic->>Cryptic: Generate PQC key pair
Cryptic-->>Wallet: { key_id, public_key }
Wallet->>Wallet: Store key_id locally

Note over User,Blockchain: Post-Quantum Transaction
User->>Wallet: Initiate transaction
Wallet->>Wallet: Build transaction payload
Wallet->>Cryptic: POST /keys/{key_id}/sign<br/>{ message: tx_hash }
Cryptic->>Cryptic: Sign with Dilithium3
Cryptic-->>Wallet: { signature }
Wallet->>Wallet: Attach PQC signature to tx
Wallet->>Blockchain: Submit dual-signed transaction<br/>(ECDSA + Dilithium3)
Blockchain->>Blockchain: Verify both signatures
Blockchain-->>User: ✅ Transaction confirmed

Note over Blockchain: Future quantum computer<br/>cannot forge PQC signature" %}
```

**Problem**: Most blockchain protocols use ECDSA/EdDSA, vulnerable to quantum attacks

**Solution**: Cryptic provides post-quantum signing for:

* Transaction signing
* Multi-sig wallets
* Smart contract deployment
* Cross-chain bridges

**Case Study: Filecoin**

* Use Case: Quantum-resistant storage proofs
* Implementation: Dilithium3 signatures for proof-of-spacetime
* Benefits: Future-proof against quantum attacks on storage network

**Integration Pattern**:

1. User authenticates with existing wallet (chain signature)
2. Generate PQC key pair in Cryptic
3. Dual-sign transactions: Traditional (ECDSA) + PQC (Dilithium3)
4. Blockchain validates both signatures
5. Gradual transition as ecosystem adopts PQC

#### 6.2 Certificate Authorities

**Problem**: X.509 certificates will need post-quantum signatures

**Solution**: Cryptic CA integration

* Generate PQC root and intermediate certificates
* Sign certificate requests with Dilithium3
* Hybrid classical/PQC certificate chains during transition

#### 6.3 Secure Messaging

**Problem**: Signal, WhatsApp use ECDH - quantum vulnerable

**Solution**: Kyber768 for key exchange

* Post-quantum key encapsulation
* Forward secrecy
* Hybrid X25519 + Kyber768 during transition

#### 6.4 Document Signing

**Problem**: PDF signatures, code signing uses RSA/ECDSA

**Solution**: Dilithium3 signatures

* Legal document signing
* Software package signing
* Notarization services

#### 6.5 IoT & Edge Computing

**Problem**: IoT devices lack resources for PQC

**Solution**: Cryptic as crypto accelerator

* Offload PQC operations to TEE
* Lightweight client SDK
* Session-based authentication