(Ruby) Duplicate openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

1. Creates a SHA256 digest of the contents of the input file.
2. Verifies the SHA256 digest using the public key.

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

pubKey = Chilkat::CkPublicKey.new()

# Load the public key from an PEM file:
success = pubKey.LoadFromFile("pubKey.pem")
if (success != true)
    print pubKey.lastErrorText() + "\n";
    exit
end

# Load the data of the original file that was signed.
bdFileData = Chilkat::CkBinData.new()
success = bdFileData.LoadFile("in.dat")

# Load the signature.
bdSig = Chilkat::CkBinData.new()
success = bdSig.LoadFile("signature.sig")

rsa = Chilkat::CkRsa.new()

# Import the public key into the RSA component:
success = rsa.ImportPublicKeyObj(pubKey)
if (success != true)
    print rsa.lastErrorText() + "\n";
    exit
end

# OpenSSL uses big-endian.
rsa.put_LittleEndian(false)

success = rsa.VerifyBd(bdFileData,"sha256",bdSig)
if (success != true)
    print rsa.lastErrorText() + "\n";
    print "The signature was invalid." + "\n";
    exit
end

print "The signature was verified." + "\n";