(Classic ASP) Verify an RSA Signature Against the Signed Hash

See more Apple Keychain Examples

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

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

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<%
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.BinData")
set bd = Server.CreateObject("Chilkat.BinData")

For i = 0 To 100
    success = bd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex")
Next
sha256_base64 = bd.GetHash("sha256","base64")
Response.Write "<pre>" & Server.HTMLEncode( "sha256 hash in base64 format: " & sha256_base64) & "</pre>"

base64_rsa_sig = "AwF2BbOvL6jA5DwmMAc9n6J2Cc8PI6Rj5W079+aKJcIEtPWRzHor0Bvc3aftGM3Jbgj6SXlIC3M3RYS7UZOnfiHKFNZgbxaNT5WwsWooK42ZkC8DBZl0p7OunBUKd5SciUo+TKilioeUkriN3L1Zl9hwi3HVDVqgVo3XXskwIftSqLSFlepTLTmOWj9Y93dp8J4D9RyLtNgFQBc0WB22tyJTsuY56mLcWe1AMF3LizB9OrbwjynF2u16xWlrJdugccz795fJBUV9aQSD+8S3KeqwQhoi8RK1uhD68aGCyaSpBq0NZ8COAkn7MXaF4POxrAAt8udfHM+PRfSOptcH/w=="

' Get the public key to be used for signature verification.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.PublicKey")
set pubKey = Server.CreateObject("Chilkat.PublicKey")
success = pubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( pubKey.LastErrorText) & "</pre>"
    Response.End
End If

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Rsa")
set rsa = Server.CreateObject("Chilkat.Rsa")
success = rsa.ImportPublicKeyObj(pubKey)

' Verify the hash against the signature.
rsa.EncodingMode = "base64"
success = rsa.VerifyHashENC(sha256_base64,"sha256",base64_rsa_sig)

If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( rsa.LastErrorText) & "</pre>"
    Response.Write "<pre>" & Server.HTMLEncode( "Signature invalid.") & "</pre>"
Else
    Response.Write "<pre>" & Server.HTMLEncode( "Signature valid.") & "</pre>"
End If


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