CTR may refer to: Engineering, science and technology. Counter mode (CTR mode), a cryptographic mode of operation for block ciphers. X-ray crystal truncation rod, a technique to measure properties of crystal surfaces. Current transfer ratio, in an opto-isolator device. Content Threat Removal, a cyber security technology that defeats content threats. Government. Cooperative Threat Reduction, an initiative to secure and dismantle weapons of mass destruction in former Soviet Union states. Currency transaction report, a report about transactions that the Bank Secrecy Act requires U.S.
https://en.wikipedia.org/wiki/CTR