TC39

TC39 (Toy Cipher 39) is a simple encryption software using the Speck cipher made by the NSA for embedded software systems. This is made for my own amusement and education implementing cryptosystems.

Warning: There are ABSOLUTELY NO GUARANTEES about the security of this software. While I tried my best, there may be huge security flaws. Do NOT use this software for communicating stuff that you don't want others to see.

How it works

TC39 uses the Speck128/128 as its block cipher primitive. The implementation of Speck is adopted from the Wikipedia entry of Speck which itself is adopted from the IACR ePrint.

TC39 uses Speck128/128 in CTR mode. During encryption, a random 128 bit nonce is generated and put at the beginning of the output file. Then, TC39 processes the input file 128 bits at a time. If the entire file cannot fit in a 128 bit block, it is zero padded.

Currently the random number generator is a dummy implementation, but the core CTR mode encryption seems to work.

Todo

Implement MAC
Implement Base64 Encode and Decode for processing ciphertext
Better command line options
Implement multithreaded/parallel decode and encode
Try porting to different languages

Compilation

make clean
make

Examples

Generate key

dd if=/dev/urandom of=key bs=1 count=16

Encode

cat myname
./tc39 -e myname.in -o myname.tc39 -k key
hexdump -Cv myname.tc39

Decode

./tc39 -d myname.tc39 -o myname.out -k key
cat myname.out

hatsunearu/tc39