If working in banks is unlawful, then what is the ruling on working as an expert in counterfeiting currency and dealing with banks in this specialization?

Working in counterfeit currency detection is permissible and important. Care must be taken to deal with Islamic banks and avoid usury. Sustenance is preordained and cannot be attained through unlawful earnings. Whoever abandons something for the sake of Allah, Allah will compensate him with something better. "Indeed, the Holy Spirit has inspired in me that no soul will die until it completes its term and receives its full sustenance. So, fear Allah and be moderate in seeking sustenance. And let not the delay in receiving sustenance prompt any of you to seek it through disobedience to Allah, for what is with Allah cannot be attained except through obedience to Him." And "Indeed, you will not abandon anything for the sake of Allah, the Mighty and Majestic, except that Allah will replace it with something better for you."