user21332: I found a library for the Speck cipher here: https://github.com/Chien-Ning/ArduinoCrypto
And I'm trying to use but haven't had much luck. My code is the following:
#include <SPECK_AVR.h>
#include <SPECK_spec.h>

#include "SPECK_AVR.h"

void setup() {
  // put your setup code here, to run once:

  SpeckTxtLen = 32;
  SpeckKeyLen = 64;
  speckTxtKey[]= 0x65, 0x74, 0x69, 0x4c, 0x19, 0x18, 0x11, 0x10, 0x09, 0x08, 0x01, 0x00;

  speckKey();
  speckEnc();

  Serial.println("");
  for (int i = 0; i < SpeckTxtLen/8; i++){
  Serial.print(speckTxtKey[i], HEX);
  Serial.print(", ");
  }
}

void loop() {
  // put your main code here, to run repeatedly:

}

And I'm getting this error:
error: lvalue required as left operand of assignment

and
error: expected primary-expression before ']' token

Do you think I'm missing something in the usage of this library?
Thanks in advance

user972: speckTxtKey[]= 0x65, 0x74, 0x69, 0x4c, 0x19, 0x18, 0x11, 0x10, 0x09, 0x08, 0x01, 0x00;

That's not how you assign an array.
And you never defined a type for the array.
It sould be:
byte speckTxtKey[] = {0x65, 0x74, 0x69, 0x4c, 0x19, 0x18, 0x11, 0x10, 0x09, 0x08, 0x01, 0x00};

EDIT:
I checked the source of the library to figure out how to use it, but it doesn't seem the library is meant for actual use.
SpeckTxtLen and SpeckKeyLen are macros inside SPECK_AVR.h, which are supposed to be changed there, not in your code.
The library also defines speckTxtKey inside SPECKenc_AVR.cpp with predefined test data based on the chosen length.
This library looks like a test implementation of the speck cipher, which was just dumped onto GitHub.

21332: <p>I found a library for the Speck cipher here: <a href="https://github.com/Chien-Ning/ArduinoCrypto" rel="nofollow noreferrer">https://github.com/Chien-Ning/ArduinoCrypto</a></p>

<p>And I'm trying to use but haven't had much luck. My code is the following:</p>

<pre><code>#include &lt;SPECK_AVR.h&gt;
#include &lt;SPECK_spec.h&gt;

#include "SPECK_AVR.h"

void setup() {
  // put your setup code here, to run once:

  SpeckTxtLen = 32;
  SpeckKeyLen = 64;
  speckTxtKey[]= 0x65, 0x74, 0x69, 0x4c, 0x19, 0x18, 0x11, 0x10, 0x09, 0x08, 0x01, 0x00;

  speckKey();
  speckEnc();

  Serial.println("");
  for (int i = 0; i &lt; SpeckTxtLen/8; i++){
  Serial.print(speckTxtKey[i], HEX);
  Serial.print(", ");
  }
}

void loop() {
  // put your main code here, to run repeatedly:

}
</code></pre>

<p>And I'm getting this error:</p>

<pre><code>error: lvalue required as left operand of assignment
</code></pre>

<p>and</p>

<pre><code>error: expected primary-expression before ']' token
</code></pre>

<p>Do you think I'm missing something in the usage of this library?</p>

<p>Thanks in advance</p>
 972: <pre><code>speckTxtKey[]= 0x65, 0x74, 0x69, 0x4c, 0x19, 0x18, 0x11, 0x10, 0x09, 0x08, 0x01, 0x00;
</code></pre>

<p>That's not how you assign an array.<br>
And you never defined a type for the array.</p>

<p>It sould be:</p>

<pre><code>byte speckTxtKey[] = {0x65, 0x74, 0x69, 0x4c, 0x19, 0x18, 0x11, 0x10, 0x09, 0x08, 0x01, 0x00};
</code></pre>

<p><strong>EDIT</strong>:</p>

<p>I checked the source of the library to figure out how to use it, but it doesn't seem the library is meant for actual use.</p>

<p><code>SpeckTxtLen</code> and <code>SpeckKeyLen</code> are macros inside <em>SPECK_AVR.h</em>, which are supposed to be changed there, not in your code.</p>

<p>The library also defines <code>speckTxtKey</code> inside <em>SPECKenc_AVR.cpp</em> with predefined test data based on the chosen length.</p>

<p>This library looks like a test implementation of the speck cipher, which was just dumped onto GitHub.</p>
