CODE EXAMPLE FOR BASIC

JWT EM VBNET

Dim PrivateKey As String = "MIIEowIBAAKCAQEAjtTe7UUP/CBI9s...BLABLABLA...JfwZ2hHqFPXA9ecbhc0".Replace(vbLf, "").Replace(vbCr, "")

Dim ar1 As JObject = New JObject()
ar1.Add("typ", "JWT")
ar1.Add("alg", "RS256")

Dim header As String = Base64UrlEncoder.Encode(ar1.ToString)

Dim ar2 As JObject = New JObject()
ar2.Add("iss", "INTEGRATION_ID")
ar2.Add("sub", "GUID_VERSION_OF_USER_ID")
ar2.Add("iat", DateDiff(DateInterval.Second, New Date(1970, 1, 1), Now().ToUniversalTime))
ar2.Add("exp", DateDiff(DateInterval.Second, New Date(1970, 1, 1), DateAdd(DateInterval.Hour, 1, Now().ToUniversalTime)))
ar2.Add("aud", "account-d.docusign.com")
ar2.Add("scope", "signature")

Dim body As String = Base64UrlEncoder.Encode(ar2.ToString)

Dim stringToSign As String = header & "." & body

Dim bytesToSign() As Byte = Encoding.UTF8.GetBytes(stringToSign)

Dim keyBytes() As Byte = Convert.FromBase64String(PrivateKey)

Dim privKeyObj = Asn1Object.FromByteArray(keyBytes)
Dim privStruct = RsaPrivateKeyStructure.GetInstance(privKeyObj)

Dim sig As ISigner = SignerUtilities.GetSigner("SHA256withRSA")

sig.Init(True, New RsaKeyParameters(True, privStruct.Modulus, privStruct.PrivateExponent))

sig.BlockUpdate(bytesToSign, 0, bytesToSign.Length)
Dim signature() As Byte = sig.GenerateSignature()

Dim sign As String = Base64UrlEncoder.Encode(signature)

Return header & "." & body & "." & sign