Xojo Plugin Requires Chilkat v11.0.0+

Create a JWS Using ECDSA P-256 SHA-256

See more JSON Web Signatures (JWS) Examples

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

Dim success As Boolean
success = False

//  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.
Dim sbJwk As New Chilkat.StringBuilder
success = sbJwk.Append("{""kty"":""EC"",")
success = sbJwk.Append("""crv"":""P-256"",")
success = sbJwk.Append("""x"":""f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU"",")
success = sbJwk.Append("""y"":""x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0"",")
success = sbJwk.Append("""d"":""jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI""")
success = sbJwk.Append("}")

Dim eccKey As New Chilkat.PrivateKey
//  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..)
success = eccKey.LoadJwk(sbJwk.GetAsString())
If (success = False) Then
    System.DebugLog(eccKey.LastErrorText)
    Return
End If

//  Create the JWS Protected Header
Dim jwsProtHdr As New Chilkat.JsonObject
success = jwsProtHdr.AppendString("alg","ES256")

Dim jws As New Chilkat.Jws

//  Set the protected header:
Dim signatureIndex As Int32
signatureIndex = 0
success = jws.SetProtectedHeader(signatureIndex,jwsProtHdr)

//  Set the ECC key:
success = jws.SetPrivateKey(signatureIndex,eccKey)

//  Set the payload.
Dim bIncludeBom As Boolean
bIncludeBom = False
Dim payloadStr As String
payloadStr = "In our village, folks say God crumbles up the old moon into stars."
success = jws.SetPayload(payloadStr,"utf-8",bIncludeBom)

//  Create the JWS
//  By default, the compact serialization is used.
Dim jwsCompact As String
jwsCompact = jws.CreateJws()
If (jws.LastMethodSuccess = False) Then
    System.DebugLog(jws.LastErrorText)
    Return
End If

System.DebugLog("JWS: " + jwsCompact)

//  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.
Dim jws2 As New Chilkat.Jws

//  Load the JWS.
success = jws2.LoadJws(jwsCompact)

Dim eccPubKey As New Chilkat.PublicKey
success = eccKey.ToPublicKey(eccPubKey)

//  Set the ECC public key used for validation.
signatureIndex = 0
success = jws2.SetPublicKey(signatureIndex,eccPubKey)

//  Validate the 1st (and only) signature at index 0..
Dim v As Int32
v = jws2.Validate(signatureIndex)
If (v < 0) Then
    //  Perhaps Chilkat was not unlocked or the trial expired..
    System.DebugLog("Method call failed for some other reason.")
    System.DebugLog(jws2.LastErrorText)
    Return
End If

If (v = 0) Then
    System.DebugLog("Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both.")
    Return
End If

//  If we get here, the signature was validated..
System.DebugLog("Signature validated.")

//  Recover the original content:
System.DebugLog(jws2.GetPayload("utf-8"))

//  Examine the protected header:
Dim joseHeader As New Chilkat.JsonObject
success = jws2.GetProtectedH(signatureIndex,joseHeader)
joseHeader.EmitCompact = False

System.DebugLog("Protected (JOSE) header:")
System.DebugLog(joseHeader.Emit())

//  Output:

//  Signature validated.
//  In our village, folks say God crumbles up the old moon into stars.
//  Protected (JOSE) header:
//  { 
//    "alg": "ES256"
//  }