In August, Google announced HTTPS as a ranking signal. But in order to benefit from this ranking factor, you need to use a 2048-bit encryption. I have only seen websites with 128-bit and 256-bit encryption. Am I missing something?
2048 bit signatures
You seem to be mixing up the signed certification to that of the actual encryption rate. Nowadays most good SSL providers will use a NIST recommended 2048 bit signed certification, because SHA2 is becoming the norm and actually recommended encryption rate you should be looking for is 256bit minimal however SHA2 supports 224, 256, 384 or 512 bits.