> 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/input-format-for-precompiled-function-calls.md).

# Input Format for Precompiled Function Calls

### **1. Input Format Specification**

When invoking precompiled contracts for Dilithium5 or MLDSA-87 verification, the input must follow this structured byte format:

Copy

```
[...PUBLIC_KEY...MESSAGE...SIGNATURE]
```

#### **Field Definitions**

| Field        | Description                                                     |
| ------------ | --------------------------------------------------------------- |
| `PUBLIC_KEY` | The public key (Dilithium5: 1,312 bytes / MLDSA-87: \~3 KB)     |
| `MESSAGE`    | Original message (arbitrary length) that was signed             |
| `SIGNATURE`  | Cryptographic signature (Dilithium5: 2.8 KB / MLDSA-87: 2.5 KB) |

***

### **2. Precompiled Contract Addresses**

```
// Precompiled Contract Addresses
address constant DILITHIUM_VERIFIER = 0x0000000000000000000000000000000000000012;
address constant MLDSA_VERIFIER = 0x0000000000000000000000000000000000000013;
```

***

### **3. Verification Logic**

The precompiled contracts:

1. Validate that `SIGNATURE` matches `MESSAGE` when signed by `PUBLIC_KEY`.
2. Return `1` (success) or `0` (failure) as a 32-byte word.

***

### **4. Use Cases**

#### **4.1 Post-Quantum Secure Authentication**

* Verify off-chain signatures before executing sensitive transactions.

#### **4.2 Decentralized Identity**

* Validate quantum-proof credentials in DID (Decentralized Identifiers) systems.

#### **4.3 Gas Optimization**

* 30-50% cheaper than equivalent EVM-based signature verification.

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