Visual Basic 6.0

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. Visual Basic 6.0

Dim success As Long
success = 0

Dim bd As New ChilkatBinData
Dim i As Long
For i = 0 To 100
    success = bd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex")
Next
Dim sha256_base64 As String
sha256_base64 = bd.GetHash("sha256","base64")
Debug.Print "sha256 hash in base64 format: " & sha256_base64

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

' Get the public key to be used for signature verification.
Dim pubKey As New PublicKey
success = pubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
If (success = 0) Then
    Debug.Print pubKey.LastErrorText
    Exit Sub
End If

Dim rsa As New ChilkatRsa
success = rsa.UsePublicKey(pubKey)
If (success = 0) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

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

If (success = 0) Then
    Debug.Print rsa.LastErrorText
    Debug.Print "Signature invalid."
Else
    Debug.Print "Signature valid."
End If