Timing Method in Examples gives Large Error - Code is faster than you might think.

[budnail]

Not a big deal at all, but the method of timing the hash function also includes the time it takes to print the hash values. Typical code from examples below:

---

ms = micros(); // timing starts here
Sha256.initHmac(hmacKey1,20); // initialize and load the key - fair to include
Sha256.print("Hi There");// load the data - fair to include
printHash(Sha256.resultHmac()); //also includes time to serial print 32 hex characters
Serial.print(" Hash took : "); // includes time to print this label
Serial.print((micros() - ms)); // time calculated here
Serial.println(" micros");
Serial.println();

---

In one of my test cases, the time to perform the HMAC SHA256 was showing about 950 microseconds. After I reworked my code to not include the serial print, the time dropped to 344 microseconds. This time also included some code I added to convert the binary HMAC to Hex format.

I don't have a really good way to get accurate timing values that is worth sharing, but thought it might be a good idea to point this out for someone who might get discouraged on a slow processor. The code is much faster than the examples might indicate. Which is a good thing. I'm not suggesting that anything be changed unless there is a good place to add a note in the documentation.

[spaniakos]

You are right. I will rework some code in january, as until the 1st of
January i wont be able to test changes to the freamework. Also i will try
to make a unified hash/encryption library in order to have multiple choices.

Thanks for the remarks,
Spaniakos
On Dec 17, 2015 1:12 AM, "Bud Nail" [email protected] wrote:

Not a big deal at all, but the method of timing the hash function also
includes the time it takes to print the hash values. Typical code from

examples below:

ms = micros(); // timing starts here
Sha256.initHmac(hmacKey1,20); // initialize and load the key - fair to
include
Sha256.print("Hi There");// load the data - fair to include
printHash(Sha256.resultHmac()); //also includes time to serial print 32
hex characters
Serial.print(" Hash took : "); // includes time to print this label
Serial.print((micros() - ms)); // time calculated here
Serial.println(" micros");

Serial.println();

In one of my test cases, the time to perform the HMAC SHA256 was showing
about 950 microseconds. After I reworked my code to not include the serial
print, the time dropped to 344 microseconds. This time also included some
code I added to convert the binary HMAC to Hex format.

I don't have a really good way to get accurate timing values that is worth
sharing, but thought it might be a good idea to point this out for someone
who might get discouraged on a slow processor. The code is much faster than
the examples might indicate. Which is a good thing. I'm not suggesting that
anything be changed unless there is a good place to add a note in the
documentation.

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