The verfication is done with your public key.
Basicly its a o = m^d (mod N)
where o is the signature, m is the message and d is the private key
Because RSA has some vulnerabilites, the message gets hashed first.
To check the signature you calulate o^e = m (mod N)
where e is the public key to the former used private key.
If the hashes match the message wasnt changed durring transport.
This works because ed = 1 (mod phi(N))
while e and N again are part of the public key
and d is the private key
If you want more details, read the rfc 3447, its explained for RSA, but the principle is still the same
Link: http://tools.ietf.org/html/rfc3447#page-27
Edit: phi(x) is eulers phi function ( http://en.wikipedia.org/wiki/Euler%27s_totient_function )
Basicly its a o = m^d (mod N)
where o is the signature, m is the message and d is the private key
Because RSA has some vulnerabilites, the message gets hashed first.
To check the signature you calulate o^e = m (mod N)
where e is the public key to the former used private key.
If the hashes match the message wasnt changed durring transport.
This works because ed = 1 (mod phi(N))
while e and N again are part of the public key
and d is the private key
If you want more details, read the rfc 3447, its explained for RSA, but the principle is still the same
Link: http://tools.ietf.org/html/rfc3447#page-27
Edit: phi(x) is eulers phi function ( http://en.wikipedia.org/wiki/Euler%27s_totient_function )
thank you very much!
