# Is there a difference between the strength of Telgram's (MTproto) forward secrecy and Signal's?

If I understood correctly, the Signal protocol generates a new key after every message sent and forgets the previous one. Telegram, on the other hand, renews the key only after 100 messages or one week. Thus, is there a certain attack window (1 week / 100 messages) with Telegram's protocol?

I think renew keys after a key generation is problematic because assume that key is already generated by the application. If somehow generate key pass through a function $$H(x) = B(preImg(x))$$. In simple language a function that somehow analysis key pattern and calculate $$n$$ pre-images of $$x$$.