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# Environment Key Storage

Store the Expo signing key pair as base64-encoded environment variables.

### Encode the keys

Encode each PEM file as a single line:

```bash
base64 -i private-key.pem | tr -d '\n'
```

### Configure the server

Set the encoded public and private keys:

```dotenv
KEYS_STORAGE_TYPE=environment
PUBLIC_EXPO_KEY_B64=base64-encoded-public-key
PRIVATE_EXPO_KEY_B64=base64-encoded-private-key
```

The server validates both values during startup, and rejects raw PEM values, invalid base64, and double-encoded values.

### The CloudFront private key

If you use [CloudFront](/expo-open-ota/cdn/cloudfront.md), keep in mind that `KEYS_STORAGE_TYPE=environment` also decides where the server reads the CloudFront private key: it only looks at `PRIVATE_CLOUDFRONT_KEY_B64`, encoded the same way as the signing keys.

```dotenv
PRIVATE_CLOUDFRONT_KEY_B64=base64-encoded-cloudfront-private-key
```

The other CloudFront key sources are ignored in this mode — see [Keys](/expo-open-ota/key-store/keys.md) for the full rule.


---

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