//--------------------------------------------------------------
// 簡単なXOR暗号                                    '22.01.31 naka
//  実行例）
//   key           :Open Sesame
//
//   plain_ssid    :WiFi_AccessPoint_SSID
//   plain_passwd  :SSID_password
//   plain_token   :LINE_TOKEN_ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789
//
//   crypted_ssid  :)$GF$Z_5$D#'*D;B*SS#8#SY+%CL
//   crypted_passwd:*%/O-J_F$##5)CK`(#
//   crypted_token :#VGN-Z_*-FCG+VK1/E;M<47E1UCJ.C/`-U(S#F?C06CV)%C_0$$E8W$89(0[5(U
//
//   decrypt_ssid  :WiFi_AccessPoint_SSID
//   decrypt_passwd:SSID_password
//   decrypt_token :LINE_TOKEN_ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789
//--------------------------------------------------------------
void setup() {
  char crypted_ssid[128],crypted_passwd[128],crypted_token[128];
  char dec_ssid[128],dec_passwd[128],dec_token[128];

  Serial.begin(115200);
  
  char* key          = "Open Sesame";
  char* plain_ssid   = "WiFi_AccessPoint_SSID";
  char* plain_passwd = "SSID_password";
  char* plain_token  = "LINE_TOKEN_ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

  encrypt(crypted_ssid,plain_ssid,key);
  encrypt(crypted_passwd,plain_passwd,key);
  encrypt(crypted_token,plain_token ,key);

  decrypt(dec_ssid,crypted_ssid,key);
  decrypt(dec_passwd,crypted_passwd,key);
  decrypt(dec_token,crypted_token,key);

  Serial.printf("key           :%s\n\n",key);
  Serial.printf("plain_ssid    :%s\n",plain_ssid);
  Serial.printf("plain_passwd  :%s\n",plain_passwd);
  Serial.printf("plain_token   :%s\n",plain_token);
  Serial.printf("\n");

  Serial.printf("crypted_ssid  :%s\n",crypted_ssid);
  Serial.printf("crypted_passwd:%s\n",crypted_passwd);
  Serial.printf("crypted_token :%s\n",crypted_token);
  Serial.printf("\n");

  Serial.printf("decrypt_ssid  :%s\n",dec_ssid);
  Serial.printf("decrypt_passwd:%s\n",dec_passwd);
  Serial.printf("decrypt_token :%s\n",dec_token);
  Serial.printf("\n");

  sleep;
}

void loop() {
}

void encrypt( char*a, char*b, char* key) {
  char x[128];
  int i,j,k,m;
  k = 0;
  int n = strlen(key);
  for (i=0; b[i]!=0; i++) {
    x[i] = b[i]^key[k++];
    k %= n;
  }
  m = i;

  // 8bit -> 6bit
  // 8bit           0          1          2
  //        000000|00, 0000|0000, 00|000000        
  // 6bit        0        1        2      3  
  j = 0;
  for (i=0; i<m; j++) {
    switch (j%4) {
      case 0:
        a[j] = (x[i]&0xFC)>>2;
        break;
      case 1:
        a[j] = (x[i]&0x03)<<4 | (x[i+1]&0xF0)>>4; 
        i++;
        break;
      case 2:
        a[j] = (x[i]&0x0F)<<2 | (x[i+1]&0xC0)>>6; 
        i++;
        break;
      case 3:
        a[j] = x[i]&0x3F;
        i++; 
        break;
    }
  }

  // ascii文字に変換
  for (i=0; i<j; i++) {
    a[i] += (int)'#';
  }
  a[i] = 0;
  
}

void decrypt( char*a, char*b, char* key) {
  char x[128];
  int i,j,k,m;
  // ascii文字をbinaryに戻す
  for(i=0; b[i]!=0; i++) {
    x[i] = b[i] - (int)'#';
  }
  m = i - 1;

  // 6bit -> 8bit
  j = 0;
  for(i=0; j<m ; i++) {
    switch (i%3) {
      case 0:
        a[i] = (x[j]&0x3F)<<2 | (x[j+1]&0x30)>>4;
        j++;
        break;
      case 1:
        a[i] = (x[j]&0x0F)<<4 | (x[j+1]&0x3C)>>2; 
        j++;
        break;
      case 2:
        a[i] = (x[j]&0x03)<<6 | x[j+1]&0x3F;
        j += 2;
        break;
    }
  }
  m = i;
  
  k = 0;
  int n = strlen(key);
  for (i=0; i<m; i++) {
    a[i] ^= key[k++];
    k %= n;
  }
  a[i]= 0;
}