(PureBasic) Create JWT Using RSA (RS256, RS384, or RS512)

Demonstrates how to create a JWT using an RSA private key. This is for JOSE headers with an "alg" of RS256, RS384, or RS512. When RSA is used, the private key signs (creates) the JWT, and the public key is for verification.

This example also demonstrates how to include time constraints:

• nbf: Not Before Time
• exp: Expiration Time
• iat: Issue At Time

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkJwt.pb"
IncludeFile "CkPrivateKey.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    ; Demonstrates how to create a JWT using an RSA private key.

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

    privKey.i = CkPrivateKey::ckCreate()
    If privKey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Load an RSA private key from a PEM file.
    success.i = CkPrivateKey::ckLoadEncryptedPemFile(privKey,"qa_data/pem/rsa_passwd.pem","passwd")
    If success <> 1
        Debug CkPrivateKey::ckLastErrorText(privKey)
        CkPrivateKey::ckDispose(privKey)
        ProcedureReturn
    EndIf

    jwt.i = CkJwt::ckCreate()
    If jwt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Build the JOSE header
    jose.i = CkJsonObject::ckCreate()
    If jose.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Use RS256.  Pass the string "RS384" or "RS512" to use RSA with SHA-384 or SHA-512.
    success = CkJsonObject::ckAppendString(jose,"alg","RS256")
    success = CkJsonObject::ckAppendString(jose,"typ","JWT")

    ; Now build the JWT claims (also known as the payload)
    claims.i = CkJsonObject::ckCreate()
    If claims.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJsonObject::ckAppendString(claims,"iss","http://example.org")
    success = CkJsonObject::ckAppendString(claims,"sub","John")
    success = CkJsonObject::ckAppendString(claims,"aud","http://example.com")

    ; Set the timestamp of when the JWT was created to now.
    curDateTime.i = CkJwt::ckGenNumericDate(jwt,0)
    success = CkJsonObject::ckAddIntAt(claims,-1,"iat",curDateTime)

    ; Set the "not process before" timestamp to now.
    success = CkJsonObject::ckAddIntAt(claims,-1,"nbf",curDateTime)

    ; Set the timestamp defining an expiration time (end time) for the token
    ; to be now + 1 hour (3600 seconds)
    success = CkJsonObject::ckAddIntAt(claims,-1,"exp",curDateTime + 3600)

    ; Produce the smallest possible JWT:
    CkJwt::setCkAutoCompact(jwt, 1)

    ; Create the JWT token.  This is where the RSA signature is created.
    token.s = CkJwt::ckCreateJwtPk(jwt,CkJsonObject::ckEmit(jose),CkJsonObject::ckEmit(claims),privKey)

    Debug token


    CkPrivateKey::ckDispose(privKey)
    CkJwt::ckDispose(jwt)
    CkJsonObject::ckDispose(jose)
    CkJsonObject::ckDispose(claims)


    ProcedureReturn
EndProcedure