Faster Yet Safer: Logging System Via Fixed-Key Blockcipher

System logs are crucial for forensic analysis, but to be useful, they need to be tamper-proof. To protect the logs, a number of secure logging systems have been proposed from both academia and the industry. Unfortunately, except for the recent KennyLoggings construction, all other logging systems are broken by an attack of Paccagnella et al. (CCS 2020). In this work, we build a secure logging system that improves KennyLoggings in several fronts: adoptability, security, and performance. Our key insight for performance gain is to use AES on a fixed, known key. While this trick is widely used in secure distributed computing, this is the first time it has found an application in the area of symmetric-key cryptography.