Lianja

CMS Sign Hash

Demonstrates how to use the SignHashENC method to sign a pre-computed hash. This method creates a CMS signature (PKCS7 detached signature).

This example requires Chilkat v9.5.0.90 or later.

Lianja

llSuccess = .F.

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

loCrypt = createobject("CkCrypt2")

// Create the hash to be signed...
loCrypt.HashAlgorithm = "sha256"
loCrypt.EncodingMode = "base64"
loCrypt.Charset = "utf-8"
// Create the SHA256 hash of a string using the utf-8 byte representation.
// Return the hash as base64.
lcBase64Hash = loCrypt.HashStringENC("This is the string to be hashed")

// Load a certificate for signing.
loCert = createobject("CkCert")
llSuccess = loCert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123")
if (llSuccess = .F.) then
    ? loCert.LastErrorText
    release loCrypt
    release loCert
    return
endif

loCrypt.SetSigningCert(loCert)

// Sign the hash to create a base64 CMS signature (which does not contain the original data).
// We can get the signature in a single line of base64 by specifying "base64", or 
// we can get multi-line base64 by specifying "base64_mime".
loCrypt.EncodingMode = "base64_mime"
lcBase64CmsSig = loCrypt.SignHashENC(lcBase64Hash,"sha256","base64")
if (loCrypt.LastMethodSuccess = .F.) then
    ? loCrypt.LastErrorText
    release loCrypt
    release loCert
    return
endif

// Note: In the above call to SignHashENC, the encoding of the returned CMS signature is specified by the EncodingMode property.
// However, the encoding of the passed-in hash is indicated by the 3rd argument.

? "CMS Signature: " + lcBase64CmsSig


release loCrypt
release loCert