Arduino Serial Monitor Input 3DES Encryption

Question

I am trying to 3DES encryption using Serial Read, Found this 3DES Sample code in Github,

#include <DES.h>
DES des;
void setup() {
  Serial.begin(9600);
  Serial.println("Hello!");
}
void loop() {
  desTest();
  tdesTest();
  delay(2000);
}
void desTest()
{
  byte out[8];
  byte in[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
  byte key[] = { 0x3b, 0x38, 0x98, 0x37, 0x15, 0x20, 0xf7, 0x5e };
  
  Serial.println();
  Serial.println("========= DES test ==========");
  
  //encrypt
  Serial.print("Encrypt...");
  unsigned long time = micros();
  des.encrypt(out, in, key);
  time = micros() - time;
  Serial.print("done. (");
  Serial.print(time);
  Serial.println(" micros)");
  printArray(out);
  
  //decrypt
  for (int i = 0; i < 8; i++)
  {
    in[i] = out[i];
  }
  Serial.print("Decrypt...");
  time = micros();
  des.decrypt(out, in, key);
  time = micros() - time;
  Serial.print("done. (");
  Serial.print(time);
  Serial.println(" micros)");
  printArray(out);
}
void tdesTest()
{
  byte out[8];
  byte in[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
  byte key[] = { 
                  0x3b, 0x38, 0x98, 0x37, 0x15, 0x20, 0xf7, 0x5e, // key A
                  0x92, 0x2f, 0xb5, 0x10, 0xc7, 0x1f, 0x43, 0x6e, // key B
                  0x3b, 0x38, 0x98, 0x37, 0x15, 0x20, 0xf7, 0x5e, // key C (in this case A)
                };
  
  Serial.println();
  Serial.println("====== Triple-DES test ======");
  
  //encrypt
  Serial.print("Encrypt...");
  unsigned long time = micros();
  des.tripleEncrypt(out, in, key);
  time = micros() - time;
  Serial.print("done. (");
  Serial.print(time);
  Serial.println(" micros)");
  printArray(out);
  
  //decrypt
  for (int i = 0; i < 8; i++)
  {
    in[i] = out[i];
  }
  Serial.print("Decrypt...");
  time = micros();
  des.tripleDecrypt(out, in, key);
  time = micros() - time;
  Serial.print("done. (");
  Serial.print(time);
  Serial.println(" micros)");
  printArray(out);
}
void printArray(byte output[])
{
  for (int i = 0; i < 8; i++)
  {
    if (output[i] < 0x10)
    {
      Serial.print("0");
    }
    Serial.print(output[i], HEX);
    Serial.print(" ");
  }
  Serial.println();
}

I want to get user serial input from Serial Monitor to feed byte in[]. Which will encrypt user input, I will pad user input to 8 Bytes or restrict input to 8.

Library: https://github.com/Octoate/ArduinoDES

Could any one help me to get data from user input.

Edit 1: I was able to read the String to char and feed to byte in[] changed the code,

#include <DES.h>
DES des;

String  input;

char buf[30];
void setup() {
  Serial.begin(9600);
  Serial.println("Hello!");

}


void printArray(byte output[])
{
  for (int i = 0; i < 8; i++)
  {
    if (output[i] < 0x10)
    {
      Serial.print("0");
    }
    Serial.print(output[i], HEX);
    Serial.print(" ");
  }
  Serial.println();
}
void loop() {

  while (Serial.available() > 0) {

    String  input = Serial.readString(); // read the incoming data as string
    char buf[30];
/*
    input.toCharArray(buf, 9);
    Serial.println(buf);
*/
    input.toCharArray(buf, input.length() + 1);
    Serial.println(buf);

    
    byte out[8];
    byte in[] = {buf};
    Serial.println(buf);
    byte key[] = {
      0x3b, 0x38, 0x98, 0x37, 0x15, 0x20, 0xf7, 0x5e, // key A
      0x92, 0x2f, 0xb5, 0x10, 0xc7, 0x1f, 0x43, 0x6e, // key B
      0x3b, 0x38, 0x98, 0x37, 0x15, 0x20, 0xf7, 0x5e, // key C (in this case A)
    };

    Serial.println();
    Serial.println("====== Triple-DES test ======");

    //encrypt
    Serial.print("Encrypt...");
    unsigned long time = micros();
    des.tripleEncrypt(out, in, key);
    time = micros() - time;
    Serial.print("done. (");
    Serial.print(time);
    Serial.println(" micros)");
    printArray(out);

    //decrypt
    for (int i = 0; i < 8; i++)
    {
      in[i] = out[i];
    }
    Serial.print("Decrypt...");
    time = micros();
    des.tripleDecrypt(out, in, key);
    time = micros() - time;
    Serial.print("done. (");
    Serial.print(time);
    Serial.println(" micros)");
    printArray(out);
    delay(2000);
  }


}

But I don't think getting the correct, Please find the below,

But when I feed manually like below,

...
input.toCharArray(buf, input.length() + 1);
    Serial.println(buf);

    //tdesTest();
    byte out[8];
    byte in[] = {"12345678"}; //Manually feeding hardcoding the value need to get the value from serial read to here
    Serial.println(buf);
    byte key[] = {
      0x3b, 0x38, 0x98, 0x37, 0x15, 0x20, 0xf7, 0x5e, // key A
      0x92, 0x2f, 0xb5, 0x10, 0xc7, 0x1f, 0x43, 0x6e, // key B
      0x3b, 0x38, 0x98, 0x37, 0x15, 0x20, 0xf7, 0x5e, // key C (in this case A)
    };

    Serial.println();
    Serial.println("====== Triple-DES test ======");
...

I get the expected output,

Hi @Majenko, Thanks for the reply, I can read the serial string from while (Serial.available > 0) { a = Serial.readString(); // read the incoming data as string } But I could not find a way to feed it to the "byte in[ ]" in tdesTest Method due to unable to feed the string. — VinRocka
– VinRocka, Commented Jul 2, 2021 at 13:05
Well, that all depends on what format your input is in and what format you need to feed into the in array. — Majenko
– Majenko, Commented Jul 2, 2021 at 13:10
I want to input String from Serial and convert it to Char and feed to in[ ] @Majenko — VinRocka
– VinRocka, Commented Jul 2, 2021 at 13:46
Yes, I gathered that. But what is in the string, and how does that relate to what would be put into in[]? — Majenko
– Majenko, Commented Jul 2, 2021 at 13:48

Majenko · Accepted Answer · 2021-07-02 14:17:21Z

1

From your comments I think I understand what you are after. So, assuming you have read some string into a String object called input and you have an array in[8] to populate you can:

Clear the in[] array to a preset state
Copy the string content into in[]

As code:

memset(in, 0, 8); // Erase the contents of in[]
input.toCharArray((char *)in, 8); // Copy up to 8 bytes from the string

answered Jul 2, 2021 at 14:17

Majenko

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Comments are not for extended discussion; this conversation has been moved to chat.

Majenko
– Majenko

2021-07-03 09:02:02 +00:00
Commented Jul 3, 2021 at 9:02

Add a comment |

VinRocka · Accepted Answer · 2021-07-03 07:55:13Z

#include <DES.h>
DES des;
byte in[8];
String  input;

char buf[30];
void setup() {
  Serial.begin(9600);
  Serial.println("Hello!");

}

void tdesTest() {
  byte out[8];


  byte key[] = {
    0x3b, 0x38, 0x98, 0x37, 0x15, 0x20, 0xf7, 0x5e, // key A
    0x92, 0x2f, 0xb5, 0x10, 0xc7, 0x1f, 0x43, 0x6e, // key B
    0x3b, 0x38, 0x98, 0x37, 0x15, 0x20, 0xf7, 0x5e, // key C (in this case A)
  };

  Serial.println();
  Serial.println("====== Triple-DES test ======");

  //encrypt
  Serial.print("Encrypt...");
  unsigned long time = micros();
  des.tripleEncrypt(out, in, key);
  time = micros() - time;
  Serial.print("done. (");
  Serial.print(time);
  Serial.println(" micros)");
  printArray(out);

  //decrypt
  for (int i = 0; i < 8; i++)
  {
    in[i] = out[i];
  }
  Serial.print("Decrypt...");
  time = micros();
  des.tripleDecrypt(out, in, key);
  time = micros() - time;
  Serial.print("done. (");
  Serial.print(time);
  Serial.println(" micros)");
  printArray(out);
  delay(2000);
}


void printArray(byte output[])
{
  for (int i = 0; i < 8; i++)
  {
    if (output[i] < 0x10)
    {
      Serial.print("0");
    }
    Serial.print(output[i], HEX);
    Serial.print(" ");
  }
  Serial.println();
}

void loop() {

  while (Serial.available() > 0) {

    String  input = Serial.readString(); // read the incoming data as string
    memset(in, 0, 9); // Erase the contents of in[]
    input.toCharArray((char *)in, 9); // Copy up to 8 bytes from the string
    tdesTest();


  }
}

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