(one's) passport to (something) phrase
That which enables one to achieve, discover or get access to something good or worth having or doing.
This certificate is my passport to a decent job.
This phone is the police's passport to solving the crime.
A softly mellifluous voice is her passport to a professional singing career.
A resource that will allow the possessor to access to power, knowledge or understanding
The origin of this phrase is not clear.
A remark you make when you are leaving on the purpose of creating a stronger impact
The letter he left before leaving was his parting shot.