[solved] Storing hash values from SHA256

Using Arduino Programming Questions
#1

I am using this code and i can not save the output of the hash function to an array of char
can u help me how to do that?

#include "sha256.h"
#include <Arduino.h>
#include "./printf.h"

void printHash(uint8_t* hash) {
  int i;
  for (i=0; i<32; i++) {
    Serial.print("0123456789abcdef"[hash[i]>>4]);
    Serial.print("0123456789abcdef"[hash[i]&0xf]);
  }
  Serial.println();
}

void setup()
{ String FinalStr="1234567890";
Sha256.init();
  Sha256.print(FinalStr);
  printHash(Sha256.result());
}
void loop()
{
  
  
}
#2

What exactly is the problem?

#3

@AWOL

the sketch just print the values of the hash
i need to store it in a char array
i tried to check what is stored in hash but it was useless and there were different value from what is printed on the serial monitor

#4

there was a thread discussing something similar here

i tried it with no result too

#5

I have tried this function but it gives diff result

String GetHash256(uint8_t* hash) {
    char tmp[16];
    String sHash256 = "";

    int i;
    for (i=0; i<32; i++) {
        sprintf(tmp, "%.2X",hash[i]);
        sHash256.concat(tmp);
    }

    return sHash256 ;
}

any help plz?

#6

I have tried this function but it gives diff result

Different from what? It would be a lot easier to help you if you showed some output.

#7

hello paulS

when i tried saving an array directly from the function sha256.result it gives me the un encoded output of the hash
i need to save the encoded version of the hash

#8

Please post the complete program that you tried along with the output. Then show what you want the output to look like.

#9

mestek86:
hello paulS

when i tried saving an array directly from the function sha256.result it gives me the un encoded output of the hash
i need to save the encoded version of the hash

Then you saved the wrong data.

#10

code

#include "sha256.h"
#include <Arduino.h>
#include "./printf.h"

void printHash(uint8_t* hash) {
  int i;
  for (i=0; i<32; i++) {
    Serial.print("0123456789abcdef"[hash[i]>>4]);
    Serial.print("0123456789abcdef"[hash[i]&0xf]);
  }
  Serial.println();
}

void setup()
{Serial.begin(9600);
  String FinalStr="1234567890";
Sha256.init();
  Sha256.print(FinalStr);
  printHash(Sha256.result());
}
void loop()
{
 
 
}

output

c775e7b757ede630cd0aa1113bd102661ab38829ca52a6422ab782862f268646

#11

Where in the code do you store anything in an array?

  printHash(Sha256.result());

What, EXACTLY, is the return type of result()?

    Serial.print("0123456789abcdef"[hash[i]>>4]);

In English, what, exactly, do you think that statement is doing? It seems like you want to store the same value you print, in an array. So, why don't you?

#12

when i tried another code

#include "sha256.h"
#include <Arduino.h>
#include "./printf.h"

void printHash(uint8_t* hash) {
  int i;
  for (i=0; i<32; i++) {
    Serial.print("0123456789abcdef"[hash[i]>>4]);
    Serial.print("0123456789abcdef"[hash[i]&0xf]);
  }
  Serial.println();
}

void copyHash(char* buf, uint8_t* hash) {
  int i, j = 0;
  for (i = 0; i < 32; i++) {
    buf[j++] = "0123456789abcdef"[hash[i]>>4];
    buf[j++] = "0123456789abcdef"[hash[i]&0xf];
  }
  buf[j] = 0;
}


void setup()
{Serial.begin(9600);
  String FinalStr="1234567890";
Sha256.init();
  Sha256.print(FinalStr);
  printHash(Sha256.result());
  char buf[65];
  copyHash(buf, Sha256.result());
  for (int k=0;k<65;k++)
  Serial.print(buf[k]);
}


void loop()
{
 
 
}

output

c775e7b757ede630cd0aa1113bd102661ab38829ca52a6422ab782862f268646
2f64612d9642afc666117f4d4fc87c17dba06ad091e1ce611f70020f2278337e

#13

PaulS:
Where in the code do you store anything in an array?

  printHash(Sha256.result());

What, EXACTLY, is the return type of result()?

    Serial.print("0123456789abcdef"[hash[i]>>4]);

In English, what, exactly, do you think that statement is doing? It seems like you want to store the same value you print, in an array. So, why don't you?

cz i am not familiar with c++ or do not know even what to search to know how this statement is written or its meaning

#14

finally solved

#include "sha256.h"
void setup(void)
{char encoded[64];
        Serial.begin(9600);

        // this is actually the RFC4231 4.3 test

        Sha256.init();
        Sha256.print("123");
        uint8_t * result = Sha256.result();

       
        for (int i = 0; i < 32; i++) {
                Serial.print("0123456789abcdef"[result[i] >> 4]);
                Serial.print("0123456789abcdef"[result[i] & 0xf]);
                
                for(int i = 0; i < 64; i+=2)
                    {
                      encoded[i] = "0123456789abcdef"[result[i / 2] >> 4];
                      encoded[i + 1] = "0123456789abcdef"[result[i / 2] & 0xf];
                    }
        }
        Serial.print("\n");
                for(int z = 0; z < 64; z++)
                Serial.print(encoded[z]);
}


void loop(void)
{}

this is the code that worked for me finally
thank u fo every one who tried to help me
special thanks to daknuett for his support after posting my question at his github

https://github.com/daknuett/cryptosuite2/issues/9

#15