(PowerBuilder) Validate a JWS Using ECDSA P-256 SHA-256

Validates a JSON Web Signature (JWS) that uses ECDSA P-256 SHA-256

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

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

integer li_rc
oleobject loo_SbPubKey
oleobject loo_PubKey
integer li_Success
oleobject loo_Jws
integer li_SignatureIndex
oleobject loo_SbJws
integer v
oleobject loo_JoseHeader

// 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.

// This example takes a JSON signature in compact serialization format,
// and uses an ECDSA public key to validate and recover the protected header and payload.

// We only need a public key for signature validation.  This is the ECDSA public key
// that is used:

//      {"kty":"EC", 
//       "crv":"P-256", 
//       "x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU", 
//       "y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0" 
//      } 

loo_SbPubKey = create oleobject
// Use "Chilkat_9_5_0.StringBuilder" for versions of Chilkat < 10.0.0
li_rc = loo_SbPubKey.ConnectToNewObject("Chilkat.StringBuilder")
if li_rc < 0 then
    destroy loo_SbPubKey
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_SbPubKey.Append("{~"kty~":~"EC~",")
loo_SbPubKey.Append("~"crv~":~"P-256~",")
loo_SbPubKey.Append("~"x~":~"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU~",")
loo_SbPubKey.Append("~"y~":~"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0~"")
loo_SbPubKey.Append("}")

loo_PubKey = create oleobject
// Use "Chilkat_9_5_0.PublicKey" for versions of Chilkat < 10.0.0
li_rc = loo_PubKey.ConnectToNewObject("Chilkat.PublicKey")

li_Success = loo_PubKey.LoadFromString(loo_SbPubKey.GetAsString())
if li_Success <> 1 then
    Write-Debug loo_PubKey.LastErrorText
    destroy loo_SbPubKey
    destroy loo_PubKey
    return
end if

loo_Jws = create oleobject
// Use "Chilkat_9_5_0.Jws" for versions of Chilkat < 10.0.0
li_rc = loo_Jws.ConnectToNewObject("Chilkat.Jws")

// Set the ECC public key:
li_SignatureIndex = 0
loo_Jws.SetPublicKey(li_SignatureIndex,loo_PubKey)

// Load the JWS.
loo_SbJws = create oleobject
// Use "Chilkat_9_5_0.StringBuilder" for versions of Chilkat < 10.0.0
li_rc = loo_SbJws.ConnectToNewObject("Chilkat.StringBuilder")

loo_SbJws.Append("eyJhbGciOiJFUzI1NiJ9")
loo_SbJws.Append(".")
loo_SbJws.Append("eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt")
loo_SbJws.Append("cGxlLmNvbS9pc19yb290Ijp0cnVlfQ")
loo_SbJws.Append(".")
loo_SbJws.Append("DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA")
loo_SbJws.Append("pmWQxfKTUJqPP3-Kg6NU1Q")

li_Success = loo_Jws.LoadJwsSb(loo_SbJws)
if li_Success <> 1 then
    Write-Debug loo_Jws.LastErrorText
    destroy loo_SbPubKey
    destroy loo_PubKey
    destroy loo_Jws
    destroy loo_SbJws
    return
end if

// Validate the 1st (and only) signature at index 0..
v = loo_Jws.Validate(li_SignatureIndex)
if v < 0 then
    // Perhaps Chilkat was not unlocked or the trial expired..
    Write-Debug "Method call failed for some other reason."
    Write-Debug loo_Jws.LastErrorText
    destroy loo_SbPubKey
    destroy loo_PubKey
    destroy loo_Jws
    destroy loo_SbJws
    return
end if

if v = 0 then
    Write-Debug "Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both."
    destroy loo_SbPubKey
    destroy loo_PubKey
    destroy loo_Jws
    destroy loo_SbJws
    return
end if

// If we get here, the signature was validated..
Write-Debug "Signature validated."
Write-Debug "--"

// Recover the original content:
Write-Debug "Recovered content:"
Write-Debug loo_Jws.GetPayload("utf-8")
Write-Debug "--"

// Examine the protected header:
loo_JoseHeader = loo_Jws.GetProtectedHeader(li_SignatureIndex)
if loo_Jws.LastMethodSuccess <> 1 then
    Write-Debug "No protected header found at the given index."
    destroy loo_SbPubKey
    destroy loo_PubKey
    destroy loo_Jws
    destroy loo_SbJws
    return
end if

loo_JoseHeader.EmitCompact = 0

Write-Debug "Protected (JOSE) header:"
Write-Debug loo_JoseHeader.Emit()
destroy loo_JoseHeader

// Output:

// 	Signature validated.
// 	--
// 	Recovered content:
// 	{"iss":"joe",
// 	 "exp":1300819380,
// 	 "http://example.com/is_root":true}
// 	--
// 	Protected (JOSE) header:
// 	{ 
// 	  "alg": "ES256"
// 	}


destroy loo_SbPubKey
destroy loo_PubKey
destroy loo_Jws
destroy loo_SbJws