As you all know, plenty of X.509 Certificates use (PKCS#1 SHA1 with RSA encryption) as the Certificate Signature Algorithm for generating the signature of 2048 Bits long. We know that SHA1 hash function generates a hash value of 160 bits, so this makes the 2048 Bits Certificate Signature Value a combination of (160 bits + 1888 bits = 2048 Bits). My question is: From where do 1888 bits come from? Are they another a hash value or are they just padding?
Can someone briefly answer this question. If you also can provide me a source or a website to read more about it since I've been trying to find an answer of this one but I haven't gotten a good resource to explain this issue.
Thank you SO MUCH in advance :)