Xbase++ Requires Chilkat v11.0.0+

RSASSA-PSS Sign String to Create Base64 PCKS7 Signature

See more Digital Signatures Examples

Signs a string to create a PKCS7 signature in the base64 encoding. The signature algorithm is RSASSA-PSS with SHA256. Xbase++

LOCAL nSuccess
LOCAL oCrypt
LOCAL oPfx
LOCAL oCert
LOCAL cOriginalText
LOCAL cPkcs7sig
LOCAL cOpaqueSig
LOCAL cOrigTxt

nSuccess := 0

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

oCrypt := CreateObject("Chilkat.Crypt2")

//  Get a digital certificate with private key from a .pfx
//  (Chilkat has many different ways to provide a cert + private key for siging.
//  Using a PFX is just one possible option.)
oPfx := CreateObject("Chilkat.Pfx")
nSuccess := oPfx:LoadPfxFile("qa_data/rsassa-pss/privatekey.pfx", "PFX_PASSWORD")
IF (nSuccess == 0)
    ? oPfx:LastErrorText
    oCrypt:destroy()
    oPfx:destroy()
    RETURN
ENDIF

//  Get the certificate to be used for signing.
//  (The typical case for a PFX is that it contains a cert with an associated private key,
//  as well as other certificates in the chain of authentication.  The cert with the private
//  key should be in the first position at index 0.)

oCert := CreateObject("Chilkat.Cert")
nSuccess := oPfx:CertAt(0, oCert)
IF (nSuccess == 0)
    ? oPfx:LastErrorText
    oCrypt:destroy()
    oPfx:destroy()
    oCert:destroy()
    RETURN
ENDIF

oCrypt:SetSigningCert(oCert)

//  Indicate that RSASSA-PSS with SHA256 should be used.
oCrypt:SigningAlg := "pss"
oCrypt:HashAlgorithm := "sha256"

oCrypt:EncodingMode := "base64"

//  Sign a string and return the base64 PKCS7 detached signature
cOriginalText := "This is a test"
cPkcs7sig := oCrypt:SignStringENC(cOriginalText)
? "Detached Signature:"
? cPkcs7sig

//  This signature looks like this:
//  MIIG5wYJKoZIhvcNAQcCoIIG2DCCBtQCAQExDzANBgl .. YToLqEwTdU87ox5g7rvw==

//  The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
//  then copy-and-paste the Base64 signature into the form and decode..

//  The signature can be verified against the original data like this:
nSuccess := oCrypt:VerifyStringENC(cOriginalText, cPkcs7sig)
? "Signature verified: " + Str(nSuccess)
nSuccess := oCrypt:VerifyStringENC("Not the original text", cPkcs7sig)
? "Signature verified: " + Str(nSuccess)

//  Now we'll create an opaque signature (the opposite of a detached signature). 
//  An opaque signature is a PKCS7 message that contains both the original data and
//  the signature.  The verification process extracts the original data.
cOpaqueSig := oCrypt:OpaqueSignStringENC(cOriginalText)
? "Opaque Signature:"
? cOpaqueSig

//  The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
//  then copy-and-paste the Base64 signature into the form and decode..

//  We can verify and extract the original data:
cOrigTxt := oCrypt:OpaqueVerifyStringENC(cOpaqueSig)
IF (oCrypt:LastMethodSuccess != 1)
    ? "Signature verification failed."
    ? oCrypt:LastErrorText
    oCrypt:destroy()
    oPfx:destroy()
    oCert:destroy()
    RETURN
ENDIF

? "Signature verified."
? "Extracted text:" + cOrigTxt

oCrypt:destroy()
oPfx:destroy()
oCert:destroy()