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Upon secure call, ZRTP-ID and CLI are checked for trustiness. If only one of this two changed (e.g.: SIM exchange, Â uninstall/install PrivateGSM PrivateWave -> a new ZRTP-ID is generated) we face a situation similar to what an MiTM attacker could try. For security reason, PrivateGSM PrivateWave warns that this situation, could be both valid and legal or a MiTM attack. So, secure call is hanged and you are forced to re-check SAS (Short Authentication Strings) to validate the other peer trust.
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