Ruby SHA1 RSA signing different from command line OpenSSL? - ruby

Question

I'm trying to implement RSA SHA1 signature verification.
To my surprise, command line OpenSSL tool doesn't generate the same key as the Ruby OpenSSL.
If I run those commands :
MacBook-Pro-de-Geoffrey:ssl_tests Escaflowne$ cat data.txt
000
MacBook-Pro-de-Geoffrey:ssl_tests Escaflowne$ openssl dgst -sha1 -binary -sign prvkey.pem -out sig.bin data.txt
MacBook-Pro-de-Geoffrey:ssl_tests Escaflowne$ openssl base64 -in sig.bin -out sig64.txt
MacBook-Pro-de-Geoffrey:ssl_tests Escaflowne$ cat sig64.txt
AJEh2kA7O3j624Kdl7UCGN1HiEk/v2LQudB+cjxw1CfmRTjcSPBjUE/EAwy8NEut
K4zYgfRwwTs7NY3AwYiUEtAe5yohUM0Qv17qSDW+G4IWjwe9PKE7Sl00umiMdszA
q/1hqeQlHKgjme7YO7H6i1UcAXmriOOjn+ySRaovsHw=
So final base64 result in command line is :
AJEh2kA7O3j624Kdl7UCGN1HiEk/v2LQudB+cjxw1CfmRTjcSPBjUE/EAwy8NEut
K4zYgfRwwTs7NY3AwYiUEtAe5yohUM0Qv17qSDW+G4IWjwe9PKE7Sl00umiMdszA
q/1hqeQlHKgjme7YO7H6i1UcAXmriOOjn+ySRaovsHw=
Now, if I try signing it through my ruby script :
def sign_message(message)
privkey = OpenSSL::PKey::RSA.new(File.read(Rails.root.join('lib', 'payment', 'prvkey.pem')))
digest = OpenSSL::Digest.new('sha1')
expected_sign = privkey.sign(digest, message)
base_64_expected_sign = [expected_sign].pack('m')
puts "Expected Signature"
puts expected_sign
puts "Base 64 Expected Signature"
puts base_64_expected_sign
return base_64_expected_sign
end
And calling the function like this :
def test_sign
message = "000"
message_signature = sign_message(message)
puts "Message Signature : #{message_signature}"
puts "Valid : #{verify_signature(message_signature, message)}"
end
I get the output :
Expected Signature
??|??n?^~?T_1Y#??BR??u???k x?*????S?L?:.7
t??tc?)崪? ?}DMp?p2??4?D-f??jT;!e
?k??5??
Base 64 Expected Signature
QjhL1zQoUdGFLVCMg06/CKeE/HdhRTOhJ/p09wkWeK0qD/afsxfcU7tMtDou
Nw3rwXw/5W68XhZ+BK1UXwIxWUDbFYlCUpu6HnWTmI5rC3QP+f50Y8kp5bSq
gQkekH1ETXDmcDKvExeSNKVELWYe3uwTalQ7IWUMyWvnF541rvo=
Message Signature : QjhL1zQoUdGFLVCMg06/CKeE/HdhRTOhJ/p09wkWeK0qD/afsxfcU7tMtDou
Nw3rwXw/5W68XhZ+BK1UXwIxWUDbFYlCUpu6HnWTmI5rC3QP+f50Y8kp5bSq
gQkekH1ETXDmcDKvExeSNKVELWYe3uwTalQ7IWUMyWvnF541rvo=
So final ruby OpenSSL signature is :
QjhL1zQoUdGFLVCMg06/CKeE/HdhRTOhJ/p09wkWeK0qD/afsxfcU7tMtDou
Nw3rwXw/5W68XhZ+BK1UXwIxWUDbFYlCUpu6HnWTmI5rC3QP+f50Y8kp5bSq
gQkekH1ETXDmcDKvExeSNKVELWYe3uwTalQ7IWUMyWvnF541rvo=
Versus command line :
AJEh2kA7O3j624Kdl7UCGN1HiEk/v2LQudB+cjxw1CfmRTjcSPBjUE/EAwy8NEut
K4zYgfRwwTs7NY3AwYiUEtAe5yohUM0Qv17qSDW+G4IWjwe9PKE7Sl00umiMdszA
q/1hqeQlHKgjme7YO7H6i1UcAXmriOOjn+ySRaovsHw=
I've been struggling with this for some time now and I don't understand what could be making a difference!
UPDATE :
Well, apparently results match if I replace my message variable with File.read(Rails.root.join('lib', 'payment', 'data.txt'))
So basically, using a string with the same value as what's in the text file doesn't give the same result.
This means it's encoding related right ?
UPDATE 2 :
So the file says its encoded in us-ascii if I run file -I data.txt
However, if I do message.encoding.name it says its loaded as UTF-8
Also, message.encode('ascii') does not alter the result of the generated signature, it still corresponds with the command line openssl.
As soon as I switch to a string "000".encode('utf-8') or "000".encode('ascii'), the signatures don't match anymore.
So encoding doesn't seem to play a role at all.
How come there's a difference between the exact same content whether it comes from reading a file or written as a string ?

Answer 1

The file data.txt has a trailing newline that you are not taking into account in your code. Using
message = "000\n"
should work.
You could also do
message = File.binread("data.txt")
to make sure you get the exact data as the command line.