128 / 256 bit SSL
128 / 256 bit SSL is also referred to as strong SSL security. The 128 / 256 bit tells users that the size of the encryption key used to encrypt the data being passed between a web browser and web server is 128 / 256 bits in size (mathematically this would be 2 to the power of 128 / 256 ). Because the size of the 128 / 256 bit key is large it is computationally unfeasible to crack and hence is known as strong SSL security.
Most web servers and web browsers support 128 / 256 bit SSL. However some versions outside of the US will only support 40 bit SSL and should be upgraded.