Zdenek,
The purpose of the id in the rest api is to be able to reference that signature as an endpoint. For example, you could use selfLink (which has the id) to update "performStaging" parameter in a subsequent REST call.
{
"enabled": true,
"id": "hXfCtmLZxvZZYi-xE5GHZQ",
"kind": "tm:asm:policies:signatures:signaturestate",
"lastUpdateMicros": 0,
"performStaging": true,
"selfLink": "https://localhost/mgmt/tm/asm/policies/7a8eq2Ll3DS51nX0DAJaUg/signatures/hXfCtmLZxvZZYi-xE5GHZQ?ver=12.1.3",
"signatureReference": {
"link": "https://localhost/mgmt/tm/asm/signatures/O-3q2O4fHlYdD97B0UIG3A?ver=12.1.3"
}
Why do you need to correlate the GUI Signature ID to the hash in REST api?
Thanks,
Tikka