# Blockchain Support

#### Supported Blockchains

| Blockchain   | Status            | Signature Standard       |
| ------------ | ----------------- | ------------------------ |
| **Cardano**  | ✅ Fully Supported | CIP-30 / CIP-8           |
| **Ethereum** | 🔜 Coming Soon    | EIP-191 (personal\_sign) |
| **Solana**   | 🔜 Coming Soon    | Ed25519                  |

> **Note:** We are currently only supporting **Cardano**. Ethereum and Solana support will be available in the coming days.

***

#### Cardano

**Supported Wallets**

| Wallet     | ID          | Status        |
| ---------- | ----------- | ------------- |
| Eternl     | eternl      | ✅ Recommended |
| Nami       | nami        | ✅ Supported   |
| Flint      | flint       | ✅ Supported   |
| Yoroi      | yoroi       | ✅ Supported   |
| Lace       | lace        | ✅ Supported   |
| Typhon     | typhoncip30 | ✅ Supported   |
| GeroWallet | gerowallet  | ✅ Supported   |
| NuFi       | nufi        | ✅ Supported   |

**Signature Standard: CIP-30**

TAGBASE uses the [CIP-30](https://cips.cardano.org/cip/CIP-30) standard for wallet communication and [CIP-8](https://cips.cardano.org/cip/CIP-8) for message signing.

**Signing Process:**

```javascript
// 1. Enable wallet
const api = await window.cardano.eternl.enable();

// 2. Get address (hex-encoded)
const addresses = await api.getUsedAddresses();
const addressHex = addresses[0];

// 3. Convert message to hex
const messageHex = Buffer.from(message).toString('hex');

// 4. Sign using signData (returns COSE_Sign1)
const { signature, key } = await api.signData(addressHex, messageHex);
```

**Response Format:**

| Field     | Description                 |
| --------- | --------------------------- |
| signature | COSE\_Sign1 signature (hex) |
| key       | COSE\_Key public key (hex)  |

**Address Formats**

TAGBASE accepts both formats and normalizes automatically:

| Format | Example                 |
| ------ | ----------------------- |
| Bech32 | addr1qx2kd28nq8ac5pr... |
| Hex    | 019bd6451e65b9f5...     |

**Token Holder Verification**

For Cardano native tokens, TAGBASE verifies:

1. **Signature validity** — Cryptographic proof the wallet signed the message
2. **Token ownership** — The wallet (or any address under the same stake key) holds the token

**Stake Key Matching:**

Cardano wallets often use multiple payment addresses under a single stake key. TAGBASE handles this by:

1. Looking up the stake address for the signing address
2. Fetching all payment addresses linked to that stake key
3. Checking if any of those addresses hold the required token

```
Signing Address → Stake Key → All Payment Addresses → Token Holder Check
```

**Token Data Requirements**

For holder verification, tokens must have:

| Field       | Required | Description                  |
| ----------- | -------- | ---------------------------- |
| asset\_id   | Yes      | Policy ID + Asset Name (hex) |
| policy\_id  | Optional | Token policy ID              |
| fingerprint | Optional | CIP-14 asset fingerprint     |

> **Note:** Blockfrost API is used for on-chain token holder lookups.

***

#### Ethereum (Coming Soon)

**Planned Wallet Support**

* MetaMask
* WalletConnect
* Coinbase Wallet
* Rainbow
* Trust Wallet

**Signature Standard: EIP-191**

```javascript
// personal_sign message signing
const signature = await ethereum.request({
  method: 'personal_sign',
  params: [message, address]
});
```

**Token Standards**

Planned support for:

* ERC-721 (NFTs)
* ERC-1155 (Multi-tokens)
* ERC-20 (Fungible tokens)

***

#### Solana (Coming Soon)

**Planned Wallet Support**

* Phantom
* Solflare
* Backpack

**Signature Standard**

Ed25519 message signing via Solana wallet adapters.

***

#### Verification Message Format

All blockchains use the same message structure:

```
Tagbase Ownership Verification

Verification ID: VRF_abc123def456
Nonce: 7a9c3f2e-1234-5678-abcd-ef0123456789
Expires: 2024-01-15T10:35:00.000Z
```

| Component       | Purpose                             |
| --------------- | ----------------------------------- |
| Verification ID | Links signature to specific product |
| Nonce           | Prevents replay attacks             |
| Expires         | 5-minute validity window            |

***

#### Security Model

**What Gets Verified**

| Check              | Description                           |
| ------------------ | ------------------------------------- |
| Signature validity | Cryptographic proof of wallet control |
| Message integrity  | Signed message matches challenge      |
| Expiry check       | Challenge not older than 5 minutes    |
| Token ownership    | Wallet holds the required token       |

**What's NOT Required**

* No transaction fees (signing is free)
* No private key exposure
* No on-chain transactions
* No token transfers

**Privacy**

* Wallet addresses are **masked** in public responses (e.g., addr1q...x7k4)
* Full addresses stored securely for verification
* No wallet balances or other assets are accessed

***

#### Network Requirements

| Blockchain | Network           |
| ---------- | ----------------- |
| Cardano    | **Mainnet only**  |
| Ethereum   | Mainnet (planned) |
| Solana     | Mainnet (planned) |

> Testnet signatures are not accepted for production verifications.

***

#### Troubleshooting

| Issue                           | Cause                                 | Solution                            |
| ------------------------------- | ------------------------------------- | ----------------------------------- |
| "Token not in wallet"           | Token held by different address       | Use wallet containing the token     |
| "Signature verification failed" | Message mismatch or invalid signature | Retry with fresh challenge          |
| "Challenge expired"             | More than 5 minutes elapsed           | Request new challenge               |
| Wallet not detected             | Extension not installed/enabled       | Install and enable wallet extension |
| Wrong network                   | Connected to testnet                  | Switch wallet to mainnet            |

***

#### API Endpoints Summary

| Endpoint                           | Blockchain | Purpose               |
| ---------------------------------- | ---------- | --------------------- |
| POST /verifications/{id}/challenge | All        | Get signing challenge |
| POST /verifications/{id}/proof     | Cardano    | Submit CIP-30 proof   |
| POST /verifications/{id}/proof     | Ethereum   | Submit EIP-191 proof  |


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.tagbase.io/extension/blockchain-support.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.