(Lianja) Create a JWS Using ECDSA P-256 SHA-256

Creates and validates a JSON Web Signature (JWS) that uses ECDSA P-256 SHA-256

Note: This example requires Chilkat v9.5.0.66 or greater.

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

// Note: This example requires Chilkat v9.5.0.66 or greater.

// Use the following ECC key loaded from JWK format.
loSbJwk = createobject("CkStringBuilder")
loSbJwk.Append('{"kty":"EC",')
loSbJwk.Append('"crv":"P-256",')
loSbJwk.Append('"x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",')
loSbJwk.Append('"y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0",')
loSbJwk.Append('"d":"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI"')
loSbJwk.Append("}")

loEccKey = createobject("CkPrivateKey")
// Note: This example loads the ECDSA key from JWK format.  Any format can be loaded
// into the private key object. (See the online reference documentation..)
llSuccess = loEccKey.LoadJwk(loSbJwk.GetAsString())
if (llSuccess <> .T.) then
    ? loEccKey.LastErrorText
    release loSbJwk
    release loEccKey
    return
endif

// Create the JWS Protected Header
loJwsProtHdr = createobject("CkJsonObject")
loJwsProtHdr.AppendString("alg","ES256")

loJws = createobject("CkJws")

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

// Set the ECC key:
loJws.SetPrivateKey(lnSignatureIndex,loEccKey)

// 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 loSbJwk
    release loEccKey
    release loJwsProtHdr
    release loJws
    return
endif

? "JWS: " + lcJwsCompact

// Note: ECC signatures use random values, so the output will be different each time a signature is produced.
// sample output:
// JWS: eyJhbGciOiJFUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.J6EGTNkeuEjehHHBu0SOKzifm8r35wbx49A5964pxzB7gannyZZPMkK7vmlaPJ-K8Xmm8cZsQySAPC12Xd8avw

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

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

loEccPubKey = loEccKey.GetPublicKey()

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

// 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 loSbJwk
    release loEccKey
    release loJwsProtHdr
    release loJws
    release loJws2
    return
endif

if (v = 0) then
    ? "Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both."
    release loSbJwk
    release loEccKey
    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 loSbJwk
    release loEccKey
    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": "ES256"
// }


release loSbJwk
release loEccKey
release loJwsProtHdr
release loJws
release loJws2