# How much data can I encrypt with RSA before I need to change the key

How much data can be encrypted with the same RSA key before it has to be changed?

I looking for the total amount of data that can be encrypted for a single key pair, not the maximum length of data per iteration.

As an example, let's take a 2048-bit RSA key with a PKCS#1 "v1.5 padding". We can compute that the the maximum size of data which can be encrypted per iteration is 245 bytes (2048 bits - 88 bits). How many times can I reuse that key assuming that it encrypts 245 bytes each time?

I find a lot of information on this for AES but almost nothing for RSA.

• There is a good aswer in security.stackexcahge for this question. No need to repeat the D.W. answer. – kelalaka Nov 13 '18 at 19:48

For RSA using PKCS #1 v1.5 padding you generally don't want to go above $$2^{31}$$ but hopefully significantly fewer iterations. This is because of the birthday bound on the random padding used. If the random padding is identical to an earlier random padding then you can distinguish if a message is identical to a previous message.