(Visual FoxPro) Sign JSON (or any Text) to Create a Detached PKCS7 Signature

Demonstrates how to sign JSON or any string using a certificate + private key from a .p12/.pfx to create a detached PKCS7 signature. (A detached signature is one that does not embed the original signed data.)

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loCrypt
LOCAL loCert
LOCAL lnSuccess
LOCAL loDetachedSig
LOCAL lcStringToSign
LOCAL lnVerified

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Crypt2')
loCrypt = CreateObject('Chilkat.Crypt2')

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Cert')
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123")
IF (lnSuccess <> 1) THEN
    ? loCert.LastErrorText
    RELEASE loCrypt
    RELEASE loCert
    CANCEL
ENDIF

* Tell the crypt component to use this cert.
lnSuccess = loCrypt.SetSigningCert(loCert)
IF (lnSuccess <> 1) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert
    CANCEL
ENDIF

loCrypt.HashAlgorithm = "sha256"

* By default, all the certs in the chain of authentication are included in the signature.
* If desired, we can choose to only include the signing certificate:
loCrypt.IncludeCertChain = 0

* Create the detached signature, which does NOT contain the original data.
* To create a PKCS7 signature that contains the original data, see CAdES Sign JSON
loCrypt.Charset = "utf-8"

lcStringToSign = '{ "abc": 123}'
loDetachedSig = loCrypt.SignString(lcStringToSign)
IF (loCrypt.LastMethodSuccess = 0) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert
    CANCEL
ENDIF

* Verify the signature against the original data.
lnVerified = loCrypt.VerifyString(lcStringToSign,loDetachedSig)
IF (lnVerified = 0) THEN
    ? loCrypt.LastErrorText
    RELEASE loCrypt
    RELEASE loCert
    CANCEL
ENDIF

? "Success!"

RELEASE loCrypt
RELEASE loCert