(Ruby) Verify the RSA Signature of a SHA256 Hash

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Demonstrates how to verify an RSA signature of a SHA256 hash.

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

require 'chilkat'

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

# Let's say you have a file containing the 32-bytes of a SHA256 hash,
# and a file that is an RSA signature of those 32 bytes.
# Here's how you verify using the RSA public key found in a PEM.

pubKey = Chilkat::CkPublicKey.new()
success = pubKey.LoadFromFile("rsaPubKey.pem")
if (success == false)
    print pubKey.lastErrorText() + "\n";
    exit
end

rsa = Chilkat::CkRsa.new()

# Get the public key.
success = rsa.ImportPublicKeyObj(pubKey)
if (success == false)
    print rsa.lastErrorText() + "\n";
    exit
end

# Get the 32-byte SHA256 hash.
bdHash = Chilkat::CkBinData.new()
success = bdHash.LoadFile("myHash.sha256")
if (success == false)
    print "Failed to load SHA256 hash." + "\n";
    exit
end

# Get the RSA signature to be validated.
bdSig = Chilkat::CkBinData.new()
success = bdSig.LoadFile("mySig.sig")
if (success == false)
    print "Failed to load RSA signature." + "\n";
    exit
end

# Verify the signature against the SHA256 hash.
enc = "base64"
rsa.put_EncodingMode(enc)
success = rsa.VerifyHashENC(bdHash.getEncoded(enc),"sha256",bdSig.getEncoded(enc))
if (success == false)
    print rsa.lastErrorText() + "\n";
    exit
end

print "Signature validated." + "\n";