I have an information that I would like to encrypt and give it to someone else. I would like to encrypt it using N separate passwords (say 5) and give each password to some other persons. However the tricky part is that I would like to have any M of them (M<=N, say M=4) to be able to get together and decipher the message. Is that possible using some sort of conventional free software?
My use case is to write a secret message, give it to one of my friends and then distribute passwords to others. However if one were to lose their part, the entire message would be lost. That is why I would like to have a redundancy. If you have any other idea how to solve this, I am open to it as well.