What is the halacha pertaining to a Jewish girl shaking hands with a non-Jewish man, or a non-religious Jewish man.
Please can you provide sources.
According to almost all poskim it is not permitted for a Jewish girl to shake a man’s hand, whether he is Jewish or not. The reason is because handshaking is done to show a relationship, even if it is only a business one, between the two people. Since all girls over the age of 11-12 are considered nida, they are considered ervah to everyone. Therefore, it is considered touching a person who is an ervah and not permitted. There are some options to avoid getting into an awkward situation, You can make sure to hold something large in your right hand, so it will be awkward to move it to the other hand and shake. You can bow slightly, as a show of respect, and that will give her the hint. If you are left with no choice you can just say that your custom is not to shake hands with men.
Please see the following link dinonline.org/2016/11/22/woman-shaking-hands/
Rabeinu Yona Sharei Teshuva 3-80, Sefer Chasidim 1090, Pri Deah 195 Sifsei Levi 20, Igros Moshe O:CH 1-113, Darcei Teshuva Y:D 183-15, Oz Nidberu 2-73, Krayono D’igrisa 1-164, Chezkas Tahara 195-63, Rivivos Efrayim 8-596(5), Shiurei Shevet Halevi 195 on Shach 20, Teshuvos V’hanhagos 4-300, Be’er Moshe 4 -130, Avnei Yoshpe 2-89(1).