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  "title" : "Combining parameters to generate a signature for SKAdNetwork 2"
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# Combining parameters to generate a signature for SKAdNetwork 2

Generate signatures to sign your ad with version 2.

## Discussion

To generate the signature, first combine the values of [Ad network install-validation keys](/documentation/StoreKit/ad-network-install-validation-keys) for the version 2.

> Important:
> Lowercase the string representation of the nonce: ``doc://com.apple.storekit/documentation/StoreKit/SKStoreProductParameterAdNetworkNonce``. Failing to do so results in an invalid signature. Only ads with valid signatures can get ad attributions.

Strings for version 2 and earlier don’t include a `fidelity-type` parameter. For version 2, combine the values into a UTF-8 string with an invisible separator (`‘\u2063’`) between them, in the exact order shown:

Listing 1. Parameter values combined, in order, for version 2.

```javascript
version + '\u2063' + ad-network-id + '\u2063' + campaign-id + '\u2063' + itunes-item-id + '\u2063' + nonce + '\u2063' + source-app-id + '\u2063' + timestamp
```

---

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