The bit size indicates the length of the key size used for the encryption during a secure SSL session. The bigger the number, the longer it takes for computer(s) to crack or break the code. Generally there are two strengths of certificate in existence - 40 bit & 128 bit. 256 bit is now also available.
- 40 bit: It is computationally feasible to crack a 40 bit key. For this reason 40 bit encryption is rarely used
- 128 /256 bit: It is computationally unfeasible to crack a 128 / 256 bit key. All banking infrastructures use 128 / 256 bit encryption. It is strongly recommended to use of 128 / 256 bit SSL encryption for any application or website