Visual Basic 6.0 Requires Chilkat v11.0.0+

Validate a JWS Using ECDSA P-521 SHA-512

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) that uses ECDSA P-521 SHA-512 Visual Basic 6.0

Dim success As Long
success = 0

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

'  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-521", 
'        "x":"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk", 
'        "y":"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDly79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2" 
'       } 

Dim sbPubKey As New ChilkatStringBuilder
success = sbPubKey.Append("{""kty"":""EC"",")
success = sbPubKey.Append("""crv"":""P-521"",")
success = sbPubKey.Append("""x"":""AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk"",")
success = sbPubKey.Append("""y"":""ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDly79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2""")
success = sbPubKey.Append("}")

Dim pubKey As New PublicKey
success = pubKey.LoadFromString(sbPubKey.GetAsString())
If (success = 0) Then
    Debug.Print pubKey.LastErrorText
    Exit Sub
End If

Dim jws As New ChilkatJws

'  Set the ECC public key:
Dim signatureIndex As Long
signatureIndex = 0
success = jws.SetPublicKey(signatureIndex,pubKey)

'  Load the JWS.
Dim sbJws As New ChilkatStringBuilder
success = sbJws.Append("eyJhbGciOiJFUzUxMiJ9")
success = sbJws.Append(".")
success = sbJws.Append("UGF5bG9hZA")
success = sbJws.Append(".")
success = sbJws.Append("AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq")
success = sbJws.Append("wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp")
success = sbJws.Append("EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn")

success = jws.LoadJwsSb(sbJws)
If (success = 0) Then
    Debug.Print jws.LastErrorText
    Exit Sub
End If

'  Validate the 1st (and only) signature at index 0..
Dim v As Long
v = jws.Validate(signatureIndex)
If (v < 0) Then
    '  Perhaps Chilkat was not unlocked or the trial expired..
    Debug.Print "Method call failed for some other reason."
    Debug.Print jws.LastErrorText
    Exit Sub
End If

If (v = 0) Then
    Debug.Print "Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both."
    Exit Sub
End If

'  If we get here, the signature was validated..
Debug.Print "Signature validated."
Debug.Print "--"

'  Recover the original content:
Debug.Print "Recovered content:"
Debug.Print jws.GetPayload("utf-8")
Debug.Print "--"

'  Examine the protected header:

Dim joseHeader As New ChilkatJsonObject
success = jws.GetProtectedH(signatureIndex,joseHeader)
If (success = 0) Then
    Debug.Print jws.LastErrorText
    Exit Sub
End If

joseHeader.EmitCompact = 0

Debug.Print "Protected (JOSE) header:"
Debug.Print joseHeader.Emit()

'  Output:
'  (the string "Payload" was the content that was signed.)

'  	Signature validated.
'  	--
'  	Recovered content:
'  	Payload
'  	--
'  	Protected (JOSE) header:
'  	{
'  	  "alg": "ES512"
'  	}