I forget a password to restaure data from old Iphone to new one, dat cripte in iTunes

If you can't remember the encryption password you won't be able to use that backup : About encrypted backups in iTunes - Apple Support

You can't use an encrypted backup without its password.

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If you don't have your password, here's what to do:

• If someone else set up your device, ask them for the password.
• Use an iCloud backup instead of iTunes. If you don't have an iCloud backup, you can make one.
• If it's still relevant, try using an older iTunes backup.