B4J Code Snippet JSON Web Token (auth0/java-jwt)

You can use this class to generate JSON Web Token (JWT) for use in Web API B4J Server.
This code is using JavaObject from Java JWT github project (https://github.com/auth0/java-jwt) by Auth0.
I only add support for HMAC algorithms. If you want, you can modify this code to support RSA and ECDSA algorithms.
Example attached.

jwt-token.b4j:
'Non-UI application (console / server application)
#Region Project Attributes
    #CommandLineArgs:
    #MergeLibraries: True
#End Region
#AdditionalJar: java-jwt-4.0.0
#AdditionalJar: jackson-core-2.13.3
#AdditionalJar: jackson-databind-2.13.3
#AdditionalJar: jackson-annotations-2.13.3

Sub Process_Globals
    Dim jwt1 As JSONWebToken
    Dim jwt2 As JSONWebToken
End Sub

Sub AppStart (Args() As String)
    ' Generate a token
    Dim secret1 As String = "secret"
    jwt1.Initialize("HMAC256", secret1, False)
    If jwt1.IsInitialized Then
        Dim generatedToken As String = CreateAndSignToken
        Log( generatedToken )
        Dim parts() As String
        parts = Regex.Split("\.", generatedToken)
        For Each part As String In parts
            Log( part )
        Next
    End If
  
    ' Verify the token
    Dim secret2 As String = "secret" ' secret2 should be same as secret1 otherwise verification will failed
    jwt2.Initialize("HMAC256", secret2, False)
    VerifyAndGetClaims(generatedToken)
  
    StartMessageLoop
End Sub

Sub CreateAndSignToken As String
    jwt1.withIssuer("Computerise")
    jwt1.withClaim(CreateMap("user": "Aeric", "isAdmin": True))
    jwt1.withExpiresAt(DateTime.Now + 180000)
    jwt1.Sign
    Return jwt1.Token
End Sub

Sub VerifyAndGetClaims (Token As String)
    jwt2.Token = Token
    jwt2.Verify
    If jwt2.Verified Then
        Dim ExpDate As String = jwt2.exp
        Log( ExpDate )
  
        Dim claims As Object = jwt2.claims
        Log( claims )
  
        Dim issuer As Object = jwt2.getClaimByKey("iss")
        Log( issuer )
      
        Dim isAdmin As Object = jwt2.getClaimByKey("isAdmin")
        Log( isAdmin )
    Else
        LogError( jwt2.Error )
    End If
End Sub

JSONWebToken.bas:
Sub Class_Globals
    Private JWT As JavaObject
    Private ALG As JavaObject
    Private builder As JavaObject
    Private verifier As JavaObject
    Private m_Token As Object
    Private m_Initialized As Boolean
    Private m_Verified As Boolean
    Private m_Exception As String
End Sub

Public Sub Initialize (Algorithm As String, Secret As String, Base64Encode As Boolean)
    Private SupportedAlgorithms As List = Array As String("HMAC256", "HMAC384", "HMAC512")
    If SupportedAlgorithms.IndexOf(Algorithm) > -1 Then
        Algorithm = Algorithm.ToUpperCase
    Else
        Log("Algorithm not supported")
        Return
    End If
    If Base64Encode Then
        Dim su As StringUtils
        Secret = su.EncodeBase64(Secret.GetBytes("UTF8"))
        'Log ( Secret )
    End If
    Private AO As JavaObject
    AO.InitializeStatic("com.auth0.jwt.algorithms.Algorithm")
    ALG = AO.RunMethod(Algorithm, Array As String(Secret))
   
    JWT.InitializeStatic("com.auth0.jwt.JWT")
    builder = JWT.RunMethodJO("create", Null)
    verifier = JWT.RunMethodJO("require", Array(ALG)).RunMethodJO("build", Null)
    m_Initialized = True
End Sub

Public Sub IsInitialized As Boolean
    Return m_Initialized
End Sub

Public Sub withIssuer (Issuer As String)
    builder.RunMethodJO("withIssuer", Array(Issuer))
End Sub

Public Sub withClaim (claim As Map)
    For Each Key In claim.Keys
        builder.RunMethodJO("withClaim", Array(Key, claim.Get(Key)))
    Next
End Sub

Public Sub withExpiresAt (Date As Long)
    Dim NativeMe As JavaObject = Me
    Dim dt As Object = NativeMe.RunMethod("JavaDate", Array(Date))
    builder.RunMethodJO("withExpiresAt", Array(dt))
End Sub

Public Sub getToken As String
    Return m_Token
End Sub

Public Sub setToken (Token As String)
    m_Token = Token
End Sub

Public Sub Sign
    m_Token = builder.RunMethodJO("sign", Array(ALG))
End Sub

Public Sub Verify As JavaObject
    Try
        Dim jo As JavaObject
        jo = verifier.RunMethod("verify", Array(m_Token))
        m_Verified = True
    Catch
        'Log(LastException)
        m_Exception = LastException.Message
        m_Verified = False
    End Try
    Return jo
End Sub

Public Sub getVerified As Boolean
    Return m_Verified
End Sub

Public Sub getError As String
    Return m_Exception
End Sub

Public Sub exp As Object
    Try
        Return Verify.RunMethod("getExpiresAt", Null)
    Catch
        Log(LastException)
    End Try
    Return Null
End Sub

Public Sub claims As Object
    Try
        Return Verify.RunMethod("getClaims", Null)
    Catch
        Log(LastException)
    End Try
    Return Null
End Sub

Public Sub getClaimByKey (Key As String) As Object
    Try
        Return claims.As(Map).Get(Key)
    Catch
        Log(LastException)
    End Try
    Return Null
End Sub

#If Java
import java.util.Date;

public Date JavaDate(Long value)
{
    return new Date(value);
}
#End If

Download Additional Jars:
https://repo1.maven.org/maven2/com/auth0/java-jwt/4.0.0/java-jwt-4.0.0.jar
https://repo1.maven.org/maven2/com/...e/jackson-core/2.13.3/jackson-core-2.13.3.jar
https://repo1.maven.org/maven2/com/...n-databind/2.13.3/jackson-databind-2.13.3.jar
https://repo1.maven.org/maven2/com/...tations/2.13.3/jackson-annotations-2.13.3.jar
 

Attachments

  • jwt-token.zip
    2 KB · Views: 78
Last edited:

aeric

Expert
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Longtime User
Example updated.
 

hatzisn

Well-Known Member
Licensed User
Longtime User
Thanks aeric. Perfect.
 

hatzisn

Well-Known Member
Licensed User
Longtime User
I have done the RSA256 part. You can get it here:

 

aeric

Expert
Licensed User
Longtime User
I have done the RSA256 part. You can get it here:

Thanks @hatzisn for the hard work. RSA is much complicated. That's why I didn't implemented it. Glad you manage to add this feature to the project.
 

Johan Hormaza

Well-Known Member
Licensed User
I have done the RSA256 part. You can get it here:

Hi, how did you implement RSA256 in @aeric example?
 
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