Stärken
Very simple, well written, works perfectly, easy to follow.
Schwächen
Bug in easy-triple-des_0.0.1 version, you probably already found but just say just in case, at beginning of tdes_encrypt() there is simple mistake, when trying to align input to 8 bytes,padding 0's at end
if ((n%8)!=0) {
for (cnt=n; cnt<8*(n/8)+8; cnt++) {
*(in+cnt)=0x00;
}
}
It assumes the "in" variable can take the extra bytes but the below is used in the example
unsigned char plain_text[32]={0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x1A, 0x1B};
Cheers
Also should do CBC, it is more common, all you need to do is have an 8 byte input vector, initialized to 0, xored against the 8 byte chunk of the input before each 8 byte encrypt. vector also receives output 8 bytes on each cycle where you do the output printf.
Also the extern params are not actually reserved an address/defined.
