CTR
/ˌsiː-tiː-ˈɑːr/
n. “Turning blocks into streams, one counter at a time.”
GCM
/ˌdʒiː-siː-ˈɛm/
n. “Authenticated encryption with speed and style.”
GCM, or Galois/Counter Mode, is a modern mode of operation for block ciphers that provides both confidentiality and data integrity. Unlike traditional encryption modes such as CBC, which only encrypts data, GCM combines encryption with authentication, ensuring that any tampering with the ciphertext can be detected during decryption.