2

I have been trying to implement XTEA encryption on Cortex M3 Microcontroller in C , in IAR IDE , so far Encryption Decryption is working , but i am facing a problem , I have To Encode Ascii Strings,but the Encrypted String Sometimes contains a 0x00 in String Array ,not in end as null terminator but in middle somewhere , so the String functions do not get the correct length of String because of this extra 0x00 they assume its Null Terminator , Problem is that I have to Transmit this String over GPRS , and the backend is also using same kind of ASCII string expecting 0x00 only at the end , in firmware also rest of String Transmission is assuming it to be Null Terminating , is there any way to Replace this 0x00 in Encrypted String with some other value , in a manner that it can also be reproduced easily later in backend , suppose i add 0x01 to each Encrypted String Array , this may make one 0xff to 0x00 , is there a way to remove this 0x00 ,

or any other Simple Encryption Algorithm for Ascii String , easily implementable on microcontroller, that guarantee Non Zero value in encrypted string , the backend guys insist on having some algorithm being used in systems , does AES algorithm insures Non zero value?

4

3 回答 3

1

与其发明新的编码方案，不如考虑使用现有的编码方案。（您的文档会更容易。）

如果您的数据是ASCII，那么您只能使用 0 到 0x7F 的代码。 Base64是最好的方法。

于 2013-08-21T22:27:31.233 回答
0

如果你不介意你的字符串增长一点，你可以在编码期间用 0x01 0x01 替换 0x00 字节，用 0x01 0x02 替换 0x01 字节。

在远端，您可以在解码期间将 0x01 0x01 替换为 0x00 并将 0x01 0x02 替换为 0x01。

例如：

0x04 0x00 0x05 0x01 在传输过程中会变成 0x04 0x01 0x01 0x05 0x01 0x02。

于 2013-08-21T21:35:46.857 回答
0

您始终可以使用 base64 或其他编码方法，但我认为按照建议转义0x00 更好。

于 2013-08-21T22:07:19.397 回答