(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.
It was often said by a photographer when he would like small children to look at the camera and smile before he took a photo.
When the photographer said “watch the birdie”, all of us looked at the camera and smiled.