Practical Network Scanning

SSL/TLS key size

It is always preferable to have longer key lengths, but for public-key cryptography (asymmetric ciphers), 2048-bit keys have the same sort of property, so longer keys are meaningless. National Institute of Standards and Technology (NIST) suggests that a 2048-bit RSA key has a strength of 112 bits, therefore there are theoretically two thousand, one hundred and twelve possibilities to crack the private key. RSA claims that 1024-bit (asymmetric) keys are likely to be cracked sometime between 2006 and 2010, and 2048-bit keys are sufficient until 2030. At the same time, longer key sizes like 4096 significantly decrease server performance, which directly impacts browser response time.

The NIST recommends 2048-bit keys for RSA. ...