Lianja

Create and Verify an Opaque PKCS7/CMS Signature

See more Digital Signatures Examples

Demonstrates how to create a PKCS7 opaque signature, and also how to verify an opaque signature. An opaque signature is different than a detached PKCS7 signature in that it contains the original data. Verifying an opaque signature retrieves the original content. Lianja

llSuccess = .F.

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

loCrypt = createobject("CkCrypt2")

// A certificate and private key is needed to create a signature.
// Chilkat provides many different ways to load a certificate and private key, such
// as from a PFX/.p12, Java keystore, JWK, Windows registry-based certificate stores, and other sources.
// This example will load the certificate from a .crt and the private key from a .key file

loCert = createobject("CkCert")
// The LoadFromFile method will automatically detect the format and load it.
llSuccess = loCert.LoadFromFile("qa_data/certs/test_12345678a.cer")
if (llSuccess <> .T.) then
    ? loCert.LastErrorText
    release loCrypt
    release loCert
    return
endif

// Our private key is in an encrypted PKCS8 format.
// If you don't know the format of your key, but you do know it's encrypted,
// and requires a password, then just call any of the Chilkat methods that load
// a private key w/ a password argument.  Chilkat will auto-detect the format
// and load it correctly even if it's not the format indicated by the method name..
loPrivKey = createobject("CkPrivateKey")
lcPassword = "12345678a"
llSuccess = loPrivKey.LoadPkcs8EncryptedFile("qa_data/certs/test_12345678a.key",lcPassword)
if (llSuccess <> .T.) then
    ? loPrivKey.LastErrorText
    release loCrypt
    release loCert
    release loPrivKey
    return
endif

// Set properties required for signing.

// Tell it to use the cert and private key we've loaded.
llSuccess = loCrypt.SetSigningCert2(loCert,loPrivKey)
if (llSuccess <> .T.) then
    ? loCrypt.LastErrorText
    release loCrypt
    release loCert
    release loPrivKey
    return
endif

// Indicate we want the opaque signature in base64 format:
loCrypt.EncodingMode = "base64"

// Sign the string using the "utf-8" byte representation:
loCrypt.Charset = "utf-8"

// Create the opaque signature:
lcOriginalData = "This is the string to be signed."
lcOpaqueSig = loCrypt.OpaqueSignStringENC(lcOriginalData)
if (loCrypt.LastMethodSuccess <> .T.) then
    ? loCrypt.LastErrorText
    release loCrypt
    release loCert
    release loPrivKey
    return
endif

? lcOpaqueSig

// The output looks like this:
// MIIPgQYJKoZIhvcNAQcCoIIPcjCCD24CAQExCzAJBgUrDgMCGgUAMC8GCSqGSIb3DQEHAaAiBCBUaGlzIGlzIHRoZSBzdHJpbmcgdG8gYmUgc...

// ----------------------------------------------------------------------------------------------
// Now let's verify the signature and retrieve the original data.
// We'll use a new Crypt2 object to keep things completely separate...

loVCrypt = createobject("CkCrypt2")

loVCrypt.EncodingMode = "base64"
loVCrypt.Charset = "utf-8"

lcExtractedData = loVCrypt.OpaqueVerifyStringENC(lcOpaqueSig)
if (loVCrypt.LastMethodSuccess <> .T.) then
    ? loVCrypt.LastErrorText
    release loCrypt
    release loCert
    release loPrivKey
    release loVCrypt
    return
endif

? "The extracted data: " + lcExtractedData

// The output is:
// The extracted data: This is the string to be signed.


release loCrypt
release loCert
release loPrivKey
release loVCrypt