Does Crystal store any sensitive information?

Question

If a developer compiles a Crystal program, what metadata will the binary file store and how to remove any sensitive information? By sensitive I mean device identificators, local IP addresses or anything else.

Answer 1

I know Crystal store basic debug information when you use:

crystal build myprogram.cr

Then you can use --debug flag to store all debug info (posible sensitive information as source code by example):

crystal build --debug myprogram.cr

To avoid debug info use --no-debug flag:

crystal build --no-debug myprogram.cr

And to optimize and obfuscate even more the binary use --release flag:

crystal build --release --no-debug myprogram.cr

As far I know compiled languages could store sensitive information when you compile using debug flags. The sensitive information commonly is the source code embed with the binary generated.

You can use objdump -s --section .comment myprogram.bin to see binary metadata like the follow:

.stdin:     file format elf64-x86-64

Contents of section .comment:
 0000 4743433a 2028474e 55292036 2e312e31  GCC: (GNU) 6.1.1
 0010 20323031 36303830 32004743 433a2028   20160802.GCC: (
 0020 474e5529 20362e33 2e312032 30313730  GNU) 6.3.1 20170
 0030 31303900 4743433a 2028474e 55292034  109.GCC: (GNU) 4
 0040 2e372e32 20323031 32313031 35202852  .7.2 20121015 (R
 0050 65642048 61742034 2e372e32 2d352900  ed Hat 4.7.2-5).