How to get X-Apple-Sig-Key and X-Apple-Signature?

Question

iOS

Maybe someone knows how X-Apple-Sig-Key and X-Apple-Signature are generated in iTunes?

<key>X-Apple-Sig-Key</key>
<string>BNTiDkxz+7WbBxpilkvaUYoJreLWzPXEk1ub3CUiYqilvLFH9Ag//odqnKSizBBER6Zscm2B1xPY3m/kYoheST4=</string>
<key>X-Apple-Signature</key>
<string>MEUCIGeBK2njVKOLbM1OrHMcziaEhTvj69zmovqbKPur84K7AiEAreyE5ksCE897XUD2Bh6N6N9M2ZWPOBwy7jbmiZtNJ/g=</string>

To activate the device, itunes sends a POST request in base64 and it still contains this data, but how it generates it and where it takes it from is not clear, can anyone know or tell me where to look?

This request is preceded by calls to some URLs, for example:

Here, as I understand it, cookies are obtained, etc. Perhaps X-Apple-Sig-Key and X-Apple-Signature are generated from cookies ..?

Also, the data itself is encrypted with something, it looks like base64, but when I decode I see bugs .. mb who knows what kind of encoding? Any advice is worth its weight in gold)

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