The base64 encode formatted output from Arduino HMAC-SHA1 does not match with

Projects Programming
1

I am working on an Arduino UNO project which is required an authorized authentication based on OAuth 1.0 to connects to the cloud. This is alike Authorizing a request to Twitter API, but I am stuck in the step of Creating a signature. The whole process of creating a signature requires algorithms like encodeURL, base64encode, and hmac-sha1. With my Arduino UNO, I use Cryptosuite library for hmac-sha1 and arduino-base64 library for base64encode. Both of them are working fine separately. However, I need to get a base64-formatted output of hmac-sha1. So I have tried this:

#include <avr/pgmspace.h>
#include <sha1.h>
#include <Base64.h>

uint8_t *in, out, i;
char b64[29];
static const char PROGMEM b64chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
char key[] = "testKey";
char basestring[] = "testing";


void printHash(uint8_t* hash) {
int i;
for (i=0; i<20; i++) {
Serial.print("0123456789abcdef"[hash[i]>>4]);
Serial.print("0123456789abcdef"[hash[i]&0xf]);
}
Serial.println();
}

void setup() {
Serial.begin(115200);

Serial.print("Result:");
Sha1.initHmac((uint8_t*)key, strlen(key));
Sha1.print(basestring);
printHash(Sha1.resultHmac());
Serial.println();

// encoding
char* input;
input = (char*)(Sha1.resultHmac());
int inputLen = strlen(input);
int encodedLen = base64_enc_len(inputLen);
char encoded[encodedLen];

// note input is consumed in this step: it will be empty afterwards
base64_encode(encoded, input, inputLen); 

Serial.print("base64 result: ");
Serial.println(encoded);

}

void loop() {
}

The output of printHash that I got is 60d41271d43b875b791e2d54c34bf3f018a29763, which is exactly same with the online verification tool.
However, I supposed to get YNQScdQ7h1t5Hi1Uw0vz8Biil2M= for the base64 result. But I got L18B0HicKRhuxmB6SIFpZP+DpHxU which seems wrong. I have tried to write a JAVA program and a python program, which also said that the output of the base64 result should be YNQScdQ7h1t5Hi1Uw0vz8Biil2M=

I also found this post: Issues talking between Arduino SHA1-HMAC and base64 encoding and Python. I have also tried the tidy function it mentioned from Adafruit-Tweet-Receipt. But the result I got from this function is also wrong.

The snippet of the function:

// base64-encode SHA-1 hash output. This is NOT a general-purpose base64
// encoder! It's stripped down for the fixed-length hash -- always 20
// bytes input, always 27 chars output + '='.
for(in = Sha1.resultHmac(), out=0; ; in += 3) { // octets to sextets
b64[out++] = in[0] >> 2;
b64[out++] = ((in[0] & 0x03) << 4) | (in[1] >> 4);
if(out >= 26) break;
b64[out++] = ((in[1] & 0x0f) << 2) | (in[2] >> 6);
b64[out++] = in[2] & 0x3f;
}
b64[out] = (in[1] & 0x0f) << 2;
// Remap sextets to base64 ASCII chars
for(i=0; i<=out; i++) b64[i] = pgm_read_byte(&b64chars[b64[i]]);
b64[i++] = '=';
b64[i++] = 0;

Basically my question is same as this post: Uint8_t to char array
But seems like there's no further discussion about the solution, I repost my question here.
And I also tried to modify the parameter of the base64 encode function from char* to unsigned char*
from
int base64_encode(char *output, char *input, int inputLen);
to
int base64_encode(char *output, unsigned char *input, int inputLen);

However, the encoded output is just same as the wrong result above.

Is there any obvious mistake I've made in here?

Thanks.

2

For the input format of base64 encoding part, I've also tried this:

  int shaLen = strlen((char*)Sha1.resultHmac());
  // encoding
  char input[shaLen];
  uint8_t* ptr = Sha1.resultHmac();
  int i = 0;
  for( i; i<shaLen; i++, ptr++ )
  {
    input[i] = DESER_INT8((*ptr));
  }
  input[i] = '\0';

by using

int8_t DESER_INT8(uint8_t x)
{
  return ((x >= (1 << 7))
          ? -(UINT8_MAX - x + 1)
          : x);
}

from this post conversion of uint8_t to sint8_t

But the output is still a wrong L18B0HicKRhuxmB6SIFpZP+DpHxU

Any further proper try I can take?
Thanks.

3

False alarm, I tried to access Sha1.resultHmac() twice. That makes the sha result different.

4

Hey ,I have same problem,can you show me your code! thanks! Sorry my english is poor.