(Lianja) Create JWS Using Private Key on a Smart Card

See more JSON Web Signatures (JWS) Examples

Creates and validates a JSON Web Signature (JWS) using the private key associated with a certificate on a smart card.

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

// Load the certificate from a smart card.
loCert = createobject("CkCert")
llSuccess = loCert.LoadFromSmartcard("")
if (llSuccess = .F.) then
    ? loCert.LastErrorText
    release loCert
    return
endif

// Note: Chilkat provides many different ways to load a certificate from a smartcard or USB token,
// such as selecting a certificate if the card contains multiple certificates with private keys,
// or working with lower-level PKCS11 or ScMinidriver API's (both of which Chilkat provides).

// If the associated private key was present on the smartcard, then you can simply
// get it from the Chilkat cert object:
loPrivKey = loCert.ExportPrivateKey()
if (loCert.LastMethodSuccess = .F.) then
    ? loCert.LastErrorText
    release loCert
    return
endif

// You can check the key type to make sure it's RSA.
// This will output "rsa" if the key is RSA.
? "Key type = " + loPrivKey.KeyType

// Create the JWS Protected Header
loJwsProtHdr = createobject("CkJsonObject")
loJwsProtHdr.AppendString("alg","RS256")

loJws = createobject("CkJws")

// Set the protected header:
lnSignatureIndex = 0
loJws.SetProtectedHeader(lnSignatureIndex,loJwsProtHdr)

// Set the RSA key:
loJws.SetPrivateKey(lnSignatureIndex,loPrivKey)

// Set the payload.
llBIncludeBom = .F.
lcPayloadStr = "In our village, folks say God crumbles up the old moon into stars."
loJws.SetPayload(lcPayloadStr,"utf-8",llBIncludeBom)

// Create the JWS
// By default, the compact serialization is used.
lcJwsCompact = loJws.CreateJws()
if (loJws.LastMethodSuccess <> .T.) then
    ? loJws.LastErrorText
    release loPrivKey
    release loCert
    release loJwsProtHdr
    release loJws
    return
endif

? "JWS: " + lcJwsCompact

// sample output:
// JWS: eyJhbGciOiJQUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.TRWhwRo5dMv9-8OzrInfJTwmUGYgjLfHk8lqF072ND-FmLWEBnUTOpY8oJXp8FdWw2SalbdOeNlrtlJjwk4XK8Ql2iJ_2qMCtxsvLPhKBOqFoAF4aBvTOEDVJDxf0DaBSiydEEtfTVV2iwBcjWabu5J2XieR5y7QZQtuHsn7T3qKBvCcCejN3Y2oqAT3qMHvu1fTms1r_91wBn_K7Wjd9UkZ1n02qQcUHJznR_OF2BgN7_KWIDAF9ZS9keoju2NPpPelO4yxa2XUPnehY3G7dHKoCxUEQR4d2Xc5voqDASTVCDqQS4PVOZdvT3Ein6-SanAlCwbWBbkvT8g6-5PImQ

// Now load the JWS, validate, and recover the original text.
loJws2 = createobject("CkJws")

// Load the JWS.
llSuccess = loJws2.LoadJws(lcJwsCompact)

loRsaPubKey = loPrivKey.GetPublicKey()
release loPrivKey

// Set the RSA public key used for validation.
lnSignatureIndex = 0
loJws2.SetPublicKey(lnSignatureIndex,loRsaPubKey)
release loRsaPubKey

// Validate the 1st (and only) signature at index 0..
v = loJws2.Validate(lnSignatureIndex)
if (v < 0) then
    // Perhaps Chilkat was not unlocked or the trial expired..
    ? "Method call failed for some other reason."
    ? loJws2.LastErrorText
    release loCert
    release loJwsProtHdr
    release loJws
    release loJws2
    return
endif

if (v = 0) then
    ? "Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both."
    release loCert
    release loJwsProtHdr
    release loJws
    release loJws2
    return
endif

// If we get here, the signature was validated..
? "Signature validated."

// Recover the original content:
? loJws2.GetPayload("utf-8")

// Examine the protected header:
loJoseHeader = loJws2.GetProtectedHeader(lnSignatureIndex)
if (loJws2.LastMethodSuccess <> .T.) then
    ? "No protected header found at the given index."
    release loCert
    release loJwsProtHdr
    release loJws
    release loJws2
    return
endif

loJoseHeader.EmitCompact = .F.

? "Protected (JOSE) header:"
? loJoseHeader.Emit()
release loJoseHeader

// Output:

// 	Signature validated.
// 	In our village, folks say God crumbles up the old moon into stars.
// 	Protected (JOSE) header:
// 	{ 
// 	  "alg": "RS256"
// 	}


release loCert
release loJwsProtHdr
release loJws
release loJws2