(Lianja) Verify an RSA Signature Against the Signed Hash

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Demonstrates how to validate an RSA Signature against the hash that was signed.

Chilkat Lianja Extension Download

Chilkat Lianja Extension

loBd = createobject("CkBinData")

for i = 0 to 100
    loBd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex")
next
lcSha256_base64 = loBd.GetHash("sha256","base64")
? "sha256 hash in base64 format: " + lcSha256_base64

lcBase64_rsa_sig = "AwF2BbOvL6jA5DwmMAc9n6J2Cc8PI6Rj5W079+aKJcIEtPWRzHor0Bvc3aftGM3Jbgj6SXlIC3M3RYS7UZOnfiHKFNZgbxaNT5WwsWooK42ZkC8DBZl0p7OunBUKd5SciUo+TKilioeUkriN3L1Zl9hwi3HVDVqgVo3XXskwIftSqLSFlepTLTmOWj9Y93dp8J4D9RyLtNgFQBc0WB22tyJTsuY56mLcWe1AMF3LizB9OrbwjynF2u16xWlrJdugccz795fJBUV9aQSD+8S3KeqwQhoi8RK1uhD68aGCyaSpBq0NZ8COAkn7MXaF4POxrAAt8udfHM+PRfSOptcH/w=="

// Get the public key to be used for signature verification.
loPubKey = createobject("CkPublicKey")
llSuccess = loPubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
if (llSuccess = .F.) then
    ? loPubKey.LastErrorText
    release loBd
    release loPubKey
    return
endif

loRsa = createobject("CkRsa")
loRsa.ImportPublicKeyObj(loPubKey)

// Verify the hash against the signature.
loRsa.EncodingMode = "base64"
llSuccess = loRsa.VerifyHashENC(lcSha256_base64,"sha256",lcBase64_rsa_sig)

if (llSuccess = .F.) then
    ? loRsa.LastErrorText
    ? "Signature invalid."
else
    ? "Signature valid."
endif



release loBd
release loPubKey
release loRsa