original passage: In academic cryptography, a "weakness" or a "break" in a scheme is usually defined quite conservatively: it might require impractical amounts of time, memory, or known plaintexts. It also might require the attacker be able to do things many real-world attackers can't: for example, the attacker may need to choose particular plaintexts to be encrypted or even to ask for plaintexts to be encrypted using several keys related to the secret key. Furthermore, it might only reveal a small amount of information, enough to prove the cryptosystem imperfect but too little to be useful to real-world attackers. Finally, an attack might only apply to a weakened version of cryptographic tools, like a reduced-round block cipher, as a step towards breaking of the full system.
original sentence: In academic cryptography, a "weakness" or a "break" in a scheme is usually defined quite conservatively: it might require impractical amounts of time, memory, or known plaintexts.
sentence2: Would an academic call a method that thwarts a scheme a break or a weakness if it requires more time than the universe has existed with current computing power?
sentence1: In academic cryptography, a "weakness" or a "break" in a scheme is usually defined quite conservatively: it might require impractical amounts of time or memory, though usually requires a practical number of known plaintexts. It also might require the attacker be able to do things many real-world attackers can't: for example, the attacker may need to choose particular plaintexts to be encrypted or even to ask for plaintexts to be encrypted using several keys related to the secret key. Furthermore, it might only reveal a small amount of information, enough to prove the cryptosystem imperfect but too little to be useful to real-world attackers. Finally, an attack might only apply to a weakened version of cryptographic tools, like a reduced-round block cipher, as a step towards breaking of the full system.