The Row Column Transformation (RC Transform) Cipher, also known as the Columnar Transposition Cipher, is a transposition cipher that arranges the plaintext in a grid with a fixed number of columns and a variable number of rows. The columns are then rearranged according to a predetermined key, and the letters are read off row by row to create the ciphertext. It was invented in the 19th century and was used during World War I and II, but it is vulnerable to known-plaintext attacks and other cryptographic attacks.