Why are the RSA signatures I generate with openssl and golang different?

Question

I use openssl command to sign the message \"Test.\", output with hexdump

# echo \"Test.\" | openssl rsautl -inkey privite.key -sign -hexdump
0000 - 09 1b ce          


        

Answer 1

The echo command prints a string with a trailing newline (\n or 0a):

> echo 'Test.' | hexdump -C
00000000  54 65 73 74 2e 0a                                 |Test..|
00000006

So in your case, you're signing Test.\n the first time, and Test. the second time in your Go program. Use echo's -n switch to suppress the trailing newline:

> echo -n 'Test.' | hexdump -C
00000000  54 65 73 74 2e                                    |Test.|
00000005