$$\begin{array}{c|lll} {k=3}\ \hline {Plaintext}&{A}&{B}&{C}&{D}&{\cdots}&{W}&{X}&{Y}&{Z}\ {CipherText}&{D}&{E}&{F}&{G}&{\cdots}&{Z}&{A}&{B}&{C}\ \end{array}$$
md测试
原文：https://www.cnblogs.com/sukfortune/p/9605815.html
