Xbase++ Requires Chilkat v11.0.0+

RSA Encryption -- Same Key Different Results

See more RSA Examples

The 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.

Xbase++

LOCAL nSuccess
LOCAL oRsa
LOCAL cPubKeyXml
LOCAL cPrivKeyXml
LOCAL oPubKey
LOCAL oPrivKey
LOCAL cPlainText
LOCAL nUsePrivateKey
LOCAL cEncryptedStr1
LOCAL cEncryptedStr2
LOCAL oRsa2
LOCAL cDecryptedStr1
LOCAL cDecryptedStr2

nSuccess := 0

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

oRsa := CreateObject("Chilkat.Rsa")

cPubKeyXml := "<RSAPublicKey><Modulus>xxyv1RDPU0MvfFIIa98HppXdcuI7zSu8uIqyGAy/VoxPvxZFX0acajznvjVRHipHbpcO6ryo2LwXUPf89qOqLb3Qd1lfD2ZnH+TQ6MZXNxfFRxTpTUd+tTR4EBYpd2t6kzq8ZRJYLdlviaMQQqUEwR54k7Op5HJYVKUcHIkP1xE=</Modulus><Exponent>AQAB</Exponent></RSAPublicKey>"

cPrivKeyXml := "<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>"

oPubKey := CreateObject("Chilkat.PublicKey")
nSuccess := oPubKey:LoadFromString(cPubKeyXml)
IF (nSuccess == 0)
    ? oPubKey:LastErrorText
    oRsa:destroy()
    oPubKey:destroy()
    RETURN
ENDIF

oPrivKey := CreateObject("Chilkat.PrivateKey")
nSuccess := oPrivKey:LoadXml(cPrivKeyXml)
IF (nSuccess == 0)
    ? oPrivKey:LastErrorText
    oRsa:destroy()
    oPubKey:destroy()
    oPrivKey:destroy()
    RETURN
ENDIF

nSuccess := oRsa:UsePublicKey(oPubKey)
IF (nSuccess == 0)
    ? oRsa:LastErrorText
    oRsa:destroy()
    oPubKey:destroy()
    oPrivKey:destroy()
    RETURN
ENDIF

//  Encrypt a string and return the encrypted data base64-encoded:
oRsa:EncodingMode := "base64"

cPlainText := "RSA gives different results with each call, weird but OK"

nUsePrivateKey := 0
cEncryptedStr1 := oRsa:EncryptStringENC(cPlainText, nUsePrivateKey)
? cEncryptedStr1

//  Do it again. The results are different...
cEncryptedStr2 := oRsa:EncryptStringENC(cPlainText, nUsePrivateKey)
? cEncryptedStr2

//  Now decrypt both strings, and the results are correct
//  in both cases:
oRsa2 := CreateObject("Chilkat.Rsa")
nSuccess := oRsa2:UsePrivateKey(oPrivKey)
IF (nSuccess == 0)
    ? oRsa:LastErrorText
    oRsa:destroy()
    oPubKey:destroy()
    oPrivKey:destroy()
    oRsa2:destroy()
    RETURN
ENDIF

oRsa2:EncodingMode := "base64"
nUsePrivateKey := 1

cDecryptedStr1 := oRsa2:DecryptStringENC(cEncryptedStr1, nUsePrivateKey)
? cDecryptedStr1

cDecryptedStr2 := oRsa2:DecryptStringENC(cEncryptedStr2, nUsePrivateKey)
? cDecryptedStr2

oRsa:destroy()
oPubKey:destroy()
oPrivKey:destroy()
oRsa2:destroy()