About RSA Public/Private Keys

Download 32-bit Chilkat RSA ActiveX (.msi)

Download All 32-bit Chilkat ActiveX Components (.zip)

Download All 64-bit Chilkat ActiveX Components (.zip)

LOCAL loCert
LOCAL lnSuccess
LOCAL loPubKey
LOCAL loPrivKey
LOCAL loRsa
LOCAL lcPrivKeyXml

loCert = CreateObject('Chilkat.Cert')

*  Load a digital certificate.
lnSuccess = loCert.LoadFromFile("digitalCert.cer")
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loCert.LastErrorText)
    QUIT
ENDIF

*  A .cer file does not contain the private key.  It should contain
*  the public key...
loPubKey = loCert.ExportPublicKey()

*  Let's have a look at it (in XML format).
? "Public Key from Certificate:"
? loPubKey.GetXml()

*  An RSA public key consists of a modulus and exponent.

*  An RSA private key includes both the modulus and exponent,
*  as well as other "big" numbers: P, Q, D, etc.

*  Let's load an RSA private key from a DER-encoded file:
loPrivKey = CreateObject('Chilkat.PrivateKey')

lnSuccess = loPrivKey.LoadRsaDerFile("PrivateKey.key")
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loPrivKey.LastErrorText)
    QUIT
ENDIF

*  If this private key is the matching half to the public key from
*  the certificate, then the modulus and exponent should
*  be identical.  (Thus, a "private key" really contains both the public part as well as the private parts...).
? "Private Key from DER:"
? loPrivKey.GetXml()

loRsa = CreateObject('Chilkat.Rsa')
lnSuccess = loRsa.UnlockComponent("Anything for 30-day trial.")
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loRsa.LastErrorText)
    QUIT
ENDIF

*  You now realize that the private key really contains both
*  private and public parts.  Therefore, we may import the private
*  key and the choose to use either the public or private in our
*  encrypt/decrypt operations:

lcPrivKeyXml = loPrivKey.GetXml()
lnSuccess = loRsa.ImportPrivateKey(lcPrivKeyXml)
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loRsa.LastErrorText)
    QUIT
ENDIF