user5427172 wrote:You seem to be more concerned with dealing with digital signatures of data than with encrypting data so I may have mislead you a little in my first response. When used in creating a digital signature, PKCS1 padding does not use random bytes for the padding; it uses fixed bytes. Since for signatures one is not trying to hide anything and one is trying to prove authenticity there is no need to try to hide the fact that two or more signatures relate to the same data. OAEPWithSHA1AndMGF1Padding always seems to have a random component.
Here is the reference regarding the OAEPWithSHA1AndMGF1Padding rather than PKCS1Padding:
What do you think about OAEPWithSHA1AndMGF1Padding vs. PKCS1Padding. Any insights?