Hash function in Arduino

Question

I’m doing a project where I need to randomly generate hash numbers.

The code has to work as follows.

A function random generates a random number, these numbers are concatenated with a String to generate the Hash of this String, ie each time a number is generated is also generated the Hash of that number, that should be loop. To generate the Hash I’m using a library called SpritzCipher.

The problem with this code is that it keeps generating the Hash of the word "random" instead of the Hash of the value concatenation with String (salt).

Follow the code I made:

#include <SpritzCipher.h>

char salt = "fkllrnjnfd";
int randNumber;
char valorConcat;

void randomico(){
  //Serial.begin(9600);
  randomSeed(analogRead(0)); // inicia a lista de valores aleatórios

  randNumber = random(100); // sorteia um número de 0 a 99

  valorConcat = char(randNumber) + salt;

  Serial.println(valorConcat);  // envia o valor de randNumber pela serial
  delay(500); // espera 500 ms
}


/* Data to input */

const byte testData[12] = {randomico};

/* Test vectors */
/* Data = 'testData' hash test vectors */
const byte testVector[32] =
{ 0xff, 0x8c, 0xf2, 0x68, 0x09, 0x4c, 0x87, 0xb9,
  0x5f, 0x74, 0xce, 0x6f, 0xee, 0x9d, 0x30, 0x03,
  0xa5, 0xf9, 0xfe, 0x69, 0x44, 0x65, 0x3c, 0xd5,
  0x0e, 0x66, 0xbf, 0x18, 0x9c, 0x63, 0xf6, 0x99
};


void testFunc(const byte ExpectedOutput[32], const byte *data, byte dataLen)
{
  byte hashLen = 32; /* 256-bit */
  byte digest[hashLen]; /* Output buffer */
  byte digest_2[hashLen]; /* Output buffer for chunk by chunk API */
  spritz_ctx hash_ctx; /* the CTX for chunk by chunk API */
  unsigned int i;

  /* Print input */
  for (i = 0; i < dataLen; i++) {
    Serial.write(data[i]);
  }
  Serial.println();

  spritz_hash_setup(&hash_ctx);
  /* For easy test: code add a byte each time */
  for (i = 0; i < dataLen; i++) {
    spritz_hash_update(&hash_ctx, data + i, 1);
  }
  spritz_hash_final(&hash_ctx, digest_2, hashLen);

  spritz_hash(digest, hashLen, data, dataLen);

  for (i = 0; i < sizeof(digest); i++) {
    if (digest[i] < 0x10) { /* To print "0F" not "F" */
      Serial.write('0');
    }
    Serial.print(digest[i], HEX);
  }

  /* Check the output */
  if (spritz_compare(digest, ExpectedOutput, sizeof(digest)) || spritz_compare(digest_2, ExpectedOutput, sizeof(digest_2))) {
    /* If the output is wrong "Alert" */
    digitalWrite(LED_BUILTIN, HIGH); /* Turn pin LED_BUILTIN On (Most boards have this LED connected to digital pin 13) */
    Serial.println("\n** WARNING: Output != Test_Vector **");
  }
  Serial.println();
}

void setup() {
  /* Initialize serial and wait for port to open */
  Serial.begin(9600);
  while (!Serial) {
    ; /* Wait for serial port to connect. Needed for Leonardo only */
  }

  /* initialize digital pin LED_BUILTIN (Most boards have this LED connected to digital pin 13) as an output */
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, LOW);
}

void loop() {
  Serial.println("[Spritz spritz_hash*() test]\n");


  /* Data: arcfour */
  testFunc(testVector, testData, sizeof(testData));

  delay(5000); /* Wait 5s */
  Serial.println();
}

Answer 1

It’s been a long time since I’ve dealt with Arduino, but I’ll take my chances if someone comes up with a different and correct solution, I erase the answer.

Try to change the function randomico thus:

string randomico(){
  //Serial.begin(9600);
  randomSeed(analogRead(0)); // inicia a lista de valores aleatórios
  randNumber = random(100); // sorteia um número de 0 a 99
  valorConcat = char(randNumber) + salt;
  Serial.println(valorConcat);  // envia o valor de randNumber pela serial
  delay(500); // espera 500 ms
  return valorConcat; // Retorna o valor concatenado
}

And on the line that calls the function: const byte testData[12] = {randomico()};