encryption/decryption with multiple keys

Question

Is it possible to encrypt data, such that it can be decrypted with several different keys?

Example:

I\'ve encrypted data with key1, but I want

Answer 1

Multiple (more than two) key RSA is maybe like this - well i'm not a mathematician, so this algorithm is not necessarily secure, i just want to give an idea with it.

m=p*q*r; p,q,r are big prime numbers

fi(m)=(p-1)(q-1)(r-1)

d==(e1*e2*e3*...*ei)^(-1) (mod fi(m)); e1...ei are arbitrary numbers, d is calculated to fulfill the equation

y1==x^e1 (mod m)

y2==y1^e2 (mod m)

y3==y2^e3 (mod m)

...

x==yi^d (mod m)

This algorithm could be used for example to increase the speed of The Onion Router.