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(Visual Basic 6.0) RSA Encryption -- Same Key Different ResultsThe RSA encryption algorithm produces different results for each call, even when encrypting the same data with the same key. Decryption however, will produce the correct results. This example demonstrates. *** The reason this occurs is that RSA encryption uses PKCS1 v1.5 padding, and this padding scheme uses random bytes. It is random bytes in the padding that causes the result to be different each time. Note: This example requires Chilkat v11.0.0 or greater.
Dim success As Long success = 0 ' This example assumes the Chilkat API to have been previously unlocked. ' See Global Unlock Sample for sample code. Dim rsa As New ChilkatRsa Dim pubKeyXml As String pubKeyXml = "<RSAPublicKey><Modulus>xxyv1RDPU0MvfFIIa98HppXdcuI7zSu8uIqyGAy/VoxPvxZFX0acajznvjVRHipHbpcO6ryo2LwXUPf89qOqLb3Qd1lfD2ZnH+TQ6MZXNxfFRxTpTUd+tTR4EBYpd2t6kzq8ZRJYLdlviaMQQqUEwR54k7Op5HJYVKUcHIkP1xE=</Modulus><Exponent>AQAB</Exponent></RSAPublicKey>" Dim privKeyXml As String privKeyXml = "<RSAKeyValue><Modulus>xxyv1RDPU0MvfFIIa98HppXdcuI7zSu8uIqyGAy/VoxPvxZFX0acajznvjVRHipHbpcO6ryo2LwXUPf89qOqLb3Qd1lfD2ZnH+TQ6MZXNxfFRxTpTUd+tTR4EBYpd2t6kzq8ZRJYLdlviaMQQqUEwR54k7Op5HJYVKUcHIkP1xE=</Modulus><Exponent>AQAB</Exponent><P>4cpW9fvG99Jsz8/AO7PDHTl+pPRAglksrR2kClLV2g9DEeFe/bvmCxLUgMCJ+0eGQ1zA6aA7McKr13zTQ7jKpQ==</P><Q>4cCS/kFlq/P1ExF37Fkh4pCodOEGutepLEG7Q/KljT3ZGlAY+2l8fGu4f+hrkUuGoFl7NOMaJflULoPIgQaq/Q==</Q><DP>lkjcSsvzqh3YKRXJiLNkyf3rypV8noYGU4+oEOsDxilkZfFRDafUPUiiQrRk4ui/d/SzvozU+ZDuWfaOk8PatQ==</DP><DQ>SYCD25i7W8Mwdibn3uIecEAdOQDTSh5RjIFSUYs9b8FFYJXXrHPp/jCsf6jS7RmkGa1Iui1/JAIL8KEjtS7QmQ==</DQ><InverseQ>EDAJa3TpNdPQ3GIdBpnTgFTQY5A60DcszsUW/iCYoXQdPVJ9BLBxVTe9jiLzGuNuzLkVBwQlCy0Bf84hACRV9A==</InverseQ><D>cMFdDYKkddlRNczaugOmOH8b1egpx2liSPs6GYZ2gFObAXJiPK8m+r6c2ckls7hrlUP0DZhi4cG6Tn7xANb0Ek17P7QquVhQYOmFy/YHzm+IJbcwwq7pJHhZBhtcjyXqfUZ+BADGE//GQbrSVwVltpOj5KcxG88NAprLn2MMxfE=</D></RSAKeyValue>" Dim pubKey As New PublicKey success = pubKey.LoadFromString(pubKeyXml) If (success = 0) Then Debug.Print pubKey.LastErrorText Exit Sub End If Dim privKey As New PrivateKey success = privKey.LoadXml(privKeyXml) If (success = 0) Then Debug.Print privKey.LastErrorText Exit Sub End If success = rsa.UsePublicKey(pubKey) If (success = 0) Then Debug.Print rsa.LastErrorText Exit Sub End If ' Encrypt a string and return the encrypted data base64-encoded: rsa.EncodingMode = "base64" Dim plainText As String plainText = "RSA gives different results with each call, weird but OK" Dim usePrivateKey As Long usePrivateKey = 0 Dim encryptedStr1 As String encryptedStr1 = rsa.EncryptStringENC(plainText,usePrivateKey) Debug.Print encryptedStr1 ' Do it again. The results are different... Dim encryptedStr2 As String encryptedStr2 = rsa.EncryptStringENC(plainText,usePrivateKey) Debug.Print encryptedStr2 ' Now decrypt both strings, and the results are correct ' in both cases: Dim rsa2 As New ChilkatRsa success = rsa2.UsePrivateKey(privKey) If (success = 0) Then Debug.Print rsa.LastErrorText Exit Sub End If rsa2.EncodingMode = "base64" usePrivateKey = 1 Dim decryptedStr1 As String decryptedStr1 = rsa2.DecryptStringENC(encryptedStr1,usePrivateKey) Debug.Print decryptedStr1 Dim decryptedStr2 As String decryptedStr2 = rsa2.DecryptStringENC(encryptedStr2,usePrivateKey) Debug.Print decryptedStr2 |
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