在下面給出的代碼塊中，我應該獲得這樣的輸出：
- 預期密文：
"'\r\u0006R\u0014\u0001\u001a\u0006\bR\a\u0006\u001c\u0012\rR\u0003\u001b\vE\t\a\b\u0004\0E\f\u0004\0\u0006S\u0011\v\u0017E\u0018\u0012\u001f\u001aR\u0001\u001b\u0014K" - 純文本：
"The quick brown fox jumps over the lazy dog." - 秘密：
"secret" - 我的輸出：
24 R
原代碼地址：https ://www.programmingalgorithms.com/algorithm/xor-encryption/c/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/***********************************************/
char *XORCipher(char *data, char *key, int dataLen, int keyLen) {
char *output = (char *)malloc(sizeof(char) * dataLen);
for (int i = 0; i < dataLen; i) {
output[i] = data[i] ^ key[i % keyLen];
}
return output;
}
int main(void) {
char *text = "The quick brown fox jumps over the lazy dog.";
char *key = "secret";
int dataLen = strlen((char *)text);
int keyLen = strlen((char *)key);
char *cipherText = XORCipher(text, key, dataLen, keyLen);
printf("%ld\n", strlen(cipherText));
char *plainText = XORCipher(cipherText, key, dataLen, keyLen);
printf("%s\n", cipherText);
printf("%s\n", plainText);
}
uj5u.com熱心網友回復：
如前所述，您的加密代碼并沒有什么問題，您只是無法列印所有這些位元組。
這是一個輕微的返工
- 將分配移到 XORCipher 函式之外（因此呼叫者負責記憶體管理）
- 添加了一個實用程式函式來列印位元組值以及 ASCII 文本
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static void XORCipher(const char *data, const char *key, char *dest, int dataLen, int keyLen) {
for (int i = 0; i < dataLen; i) {
dest[i] = data[i] ^ key[i % keyLen];
}
}
static void print_hex(const char *header, const unsigned char *data, int length) {
int i = 0;
while(i < length) {
char asc_line[17] = {0};
printf("%s(x): ", header, i);
for(int j = 0; j < 16; i , j ) {
if(i < length) {
printf("x ", data[i]);
asc_line[j] = (data[i] >= 32 && data[i] <= 127 ? data[i] : '.');
} else {
printf(" ");
}
}
printf("| %-16s |\n", asc_line);
}
printf("%s\n----\n", data);
}
int main(void) {
char *text = "The quick brown fox jumps over the lazy dog.";
char *key = "secret";
int dataLen = strlen((char *)text);
int keyLen = strlen((char *)key);
char *output = (char *)malloc(sizeof(char) * dataLen);
print_hex("Original text", text, dataLen);
XORCipher(text, key, output, dataLen, keyLen);
print_hex("Ciphered text", output, dataLen);
XORCipher(output, key, output, dataLen, keyLen);
print_hex("Deciphered text", output, dataLen);
}
輸出是
Original text(0000): 54 68 65 20 71 75 69 63 6b 20 62 72 6f 77 6e 20 | The quick brown |
Original text(0010): 66 6f 78 20 6a 75 6d 70 73 20 6f 76 65 72 20 74 | fox jumps over t |
Original text(0020): 68 65 20 6c 61 7a 79 20 64 6f 67 2e | he lazy dog. |
The quick brown fox jumps over the lazy dog.
----
Ciphered text(0000): 27 0d 06 52 14 01 1a 06 08 52 07 06 1c 12 0d 52 | '..R.....R.....R |
Ciphered text(0010): 03 1b 0b 45 09 07 08 04 00 45 0c 04 00 06 53 11 | ...E.....E....S. |
Ciphered text(0020): 0b 17 45 18 12 1f 1a 52 01 1b 14 4b | ..E....R...K |
'
RR
RE
----
Deciphered text(0000): 54 68 65 20 71 75 69 63 6b 20 62 72 6f 77 6e 20 | The quick brown |
Deciphered text(0010): 66 6f 78 20 6a 75 6d 70 73 20 6f 76 65 72 20 74 | fox jumps over t |
Deciphered text(0020): 68 65 20 6c 61 7a 79 20 64 6f 67 2e | he lazy dog. |
The quick brown fox jumps over the lazy dog.
----
（請注意，我正在破譯output后面output的內容——在這種情況下很好，因為我們知道密碼函式是逐位元組作業的。）
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