一个分组密码输入期望用长度是块大小的倍数。随着AES，输入的长度必须是16的倍数。

A block cipher expects input with a length that is a multiple of the block size. With AES, the length of the input must be a multiple of 16.

您必须向明文某种填充，使这一要求得到满足。 PKCS＃7填充是***的选择。

You must apply some sort of padding to the plaintext so that this requirement is satisfied. PKCS#7 padding is the best choice.

不过，经过再三考虑，CFB模式将块加密成一个流密码。流密码不需要填充。的.NET实现似乎在这方面被打破。

However, on second thought, CFB mode turns a block cipher into a stream cipher. Stream ciphers don't need padding. The .NET implementation seems to be broken in this regard.