(PowerBuilder) Charset Considerations when RSA Encrypting Strings

When encrypting strings, character encoding can be an issue. Encryption algorithms operate on binary data. If for example, your string includes a character such as é, the bytes used to represent it depend on the character encoding. In an "iso" encoding such as iso-8859-1, or in a "windows" encoding, such as "windows-1252", the é is represented by a single byte. In Unicode however, whether it's utf-8 or ucs-2, the é is represented by 2 bytes. When encrypting strings, the RSA component will first convert the string to the character encoding indicated by the Charset property. When decrypting strings, the RSA component converts from the character encoding indicated by the Charset property to the application's expected charset. In VB6 for example, this would be Unicode. In C++, it's ANSI. In Java, it's utf-8.

Note: This example requires Chilkat v11.0.0 or greater.

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integer li_rc
integer li_Success
oleobject loo_Rsa
string ls_PubKeyXml
oleobject loo_PubKey
string ls_PlainText
integer li_UsePrivateKey
string ls_EncryptedStr

li_Success = 0

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

loo_Rsa = create oleobject
li_rc = loo_Rsa.ConnectToNewObject("Chilkat.Rsa")
if li_rc < 0 then
    destroy loo_Rsa
    MessageBox("Error","Connecting to COM object failed")
    return
end if

// RSA public key in XML format:
ls_PubKeyXml = "<RSAPublicKey><Modulus>of3im3mRgd2NLXIGoK6uYLg6jj0Ug2b42rnqa5Tbwz2ieFqMJqt+++x2oqLYGurlz49nt+7/785g3XYWqoka4u9c9zul6YubIjnBM72dQy7rEkEfbUxgjcxqXyjZFx+FpaxFUecLu688XEu+9UA42VKiCgcl+E7TrqnfeeYpNXc=</Modulus><Exponent>AQAB</Exponent></RSAPublicKey>"

loo_PubKey = create oleobject
li_rc = loo_PubKey.ConnectToNewObject("Chilkat.PublicKey")

li_Success = loo_PubKey.LoadFromString(ls_PubKeyXml)
if li_Success = 0 then
    Write-Debug loo_PubKey.LastErrorText
    destroy loo_Rsa
    destroy loo_PubKey
    return
end if

li_Success = loo_Rsa.UsePublicKey(loo_PubKey)
if li_Success = 0 then
    Write-Debug loo_Rsa.LastErrorText
    destroy loo_Rsa
    destroy loo_PubKey
    return
end if

// Use the utf-8 character encoding.  When encrypting, the
// plain text is first converted to utf-8 bytes and then
// RSA encrypted.
loo_Rsa.Charset = "utf-8"

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

ls_PlainText = "éééé"

li_UsePrivateKey = 0
ls_EncryptedStr = loo_Rsa.EncryptStringENC(ls_PlainText,li_UsePrivateKey)
Write-Debug ls_EncryptedStr


destroy loo_Rsa
destroy loo_PubKey