Base64 编码

1
switch ( i )
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    {
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      case 1:
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        *((_BYTE *)v12 + v4) = aAbcdefghijklmn[(int)(unsigned __int8)byte_41A144[0] >> 2];
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        v5 = v4 + 1;
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        *((_BYTE *)v12 + v5) = aAbcdefghijklmn[((byte_41A144[1] & 0xF0) >> 4) | (16 * (byte_41A144[0] & 3))];
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        *((_BYTE *)v12 + ++v5) = aAbcdefghijklmn[64];
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        *((_BYTE *)v12 + ++v5) = aAbcdefghijklmn[64];
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        v4 = v5 + 1;
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        break;
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      case 2:
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        *((_BYTE *)v12 + v4) = aAbcdefghijklmn[(int)(unsigned __int8)byte_41A144[0] >> 2];
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        v6 = v4 + 1;
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        *((_BYTE *)v12 + v6) = aAbcdefghijklmn[((byte_41A144[1] & 0xF0) >> 4) | (16 * (byte_41A144[0] & 3))];
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        *((_BYTE *)v12 + ++v6) = aAbcdefghijklmn[((byte_41A144[2] & 0xC0) >> 6) | (4 * (byte_41A144[1] & 0xF))];
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        *((_BYTE *)v12 + ++v6) = aAbcdefghijklmn[64];
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        v4 = v6 + 1;
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        break;
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      case 3:
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        *((_BYTE *)v12 + v4) = aAbcdefghijklmn[(int)(unsigned __int8)byte_41A144[0] >> 2];
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        v7 = v4 + 1;
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        *((_BYTE *)v12 + v7) = aAbcdefghijklmn[((byte_41A144[1] & 0xF0) >> 4) | (16 * (byte_41A144[0] & 3))];
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        *((_BYTE *)v12 + ++v7) = aAbcdefghijklmn[((byte_41A144[2] & 0xC0) >> 6) | (4 * (byte_41A144[1] & 0xF))];
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        *((_BYTE *)v12 + ++v7) = aAbcdefghijklmn[byte_41A144[2] & 0x3F];
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        v4 = v7 + 1;
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        break;
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    }

1
#include <stdio.h>
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#include <string.h>
3

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int main(void)
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{
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    char flag[100] = "mTyqm7wjODkrNLcWl0eqO8K8gc1BPk1GNLgUpI";
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    int length = strlen(flag);
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    char t1[70] = "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz0987654321/+"; // 修改后的Base64表
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    char t2[70] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; // 标准Base64表
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    for (int i = 0; i < length; i++) // 遍历密文
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    {
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        for (int j = 0; j < 63; j++)
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        {
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            if (flag[i] == t1[j])
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            {
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                flag[i] = t2[j]; // 按标准表映射替换为标准密文
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                break;
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            }
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        }
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    }
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    printf("%s\n", flag);
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    getchar();
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}

1
  len = strlen(Str);
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  encoded_len = 4 * ((len + 2) / 3);
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  v12 = encoded_len;
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  v1 = 16 * ((encoded_len + 16) / 0x10u);
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  v2 = alloca(v1);
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  v3 = alloca(v1);
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  p_encoded = (char (*)[])&v10;
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  index = 0;
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  func(Str);
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  for ( i = 0; i < len; i += 3 )
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  {
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    value = 0;
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    for ( j = 0; j <= 2; ++j )
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    {
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      value <<= 8;
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      if ( i + j < len )
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        value |= (unsigned __int8)Str[i + j];
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    }
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    v4 = index++;
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    *((_BYTE *)p_encoded + v4) = base64_table[(value >> 18) & 0x3F];
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    v5 = index++;
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    *((_BYTE *)p_encoded + v5) = base64_table[(value >> 12) & 0x3F];
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    v6 = index++;
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    if ( i + 1 >= len )
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      v7 = 61;
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    else
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      v7 = base64_table[(value >> 6) & 0x3F];
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    *((_BYTE *)p_encoded + v6) = v7;
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    v8 = index++;
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    if ( i + 2 >= len )
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      v9 = '=';
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    else
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      v9 = base64_table[value & 0x3F];
34
    *((_BYTE *)p_encoded + v8) = v9;
35
  }
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  *((_BYTE *)p_encoded + index) = 0;
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  strcpy(Str, (const char *)p_encoded);
38
  fun(Str);

1
#include <stdio.h>
2
#include <ctype.h> // 包含字符处理函数的头文件
3

4
void toggleCase(char *str) {
5
    for (int i = 0; str[i] != '\0'; i++) {
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        // 如果是大写字母，则转换为小写
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        if (str[i] >= 'A' && str[i] <= 'Z') {
8
            str[i] = tolower(str[i]);
9
        }
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        // 如果是小写字母，则转换为大写
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        else if (str[i] >= 'a' && str[i] <= 'z') {
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            str[i] = toupper(str[i]);
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        }
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        // 其他字符不变
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    }
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}
17

18
int main() {
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    char str[100]; // 假设输入字符串的最大长度为99个字符
20

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    printf("请输入一个字符串: ");
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    fgets(str, sizeof(str), stdin); // 使用fgets读取字符串
23

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    toggleCase(str); // 调用函数进行大小写置换
25

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    printf("大小写置换后的字符串: %s", str); // 输出结果
27

28
    return 0;
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}