PureBasic

Set a Per-Recipient JWE Header

See more JSON Web Encryption (JWE) Examples

Demonstrates Jwe.SetRecipientHeader, which sets the per-recipient unprotected header for a recipient index.

Background. Per-recipient headers carry recipient-specific values such as a key id (kid), and are used with the JSON serialization forms that support multiple recipients.

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PureBasic

IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJwe.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    success.i = 0

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

    ;  Protected header: AES key-wrap with AES-256-GCM content encryption.
    header.i = CkJsonObject::ckCreate()
    If header.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckUpdateString(header,"alg","A256KW")
    CkJsonObject::ckUpdateString(header,"enc","A256GCM")
    success = CkJwe::ckSetProtectedHeader(jwe,header)
    If success = 0
        Debug CkJwe::ckLastErrorText(jwe)
        CkJwe::ckDispose(jwe)
        CkJsonObject::ckDispose(header)
        ProcedureReturn
    EndIf

    ;  The 256-bit key-wrapping key (base64) for recipient index 0.  In production, obtain the key from a
    ;  secure source rather than hard-coding it.
    base64Key.s = "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU="
    success = CkJwe::ckSetWrappingKey(jwe,0,base64Key,"base64")
    If success = 0
        Debug CkJwe::ckLastErrorText(jwe)
        CkJwe::ckDispose(jwe)
        CkJsonObject::ckDispose(header)
        ProcedureReturn
    EndIf

    ;  Set the per-recipient unprotected header for recipient 0, for example a key id used to identify
    ;  which key a recipient should use.
    recipHeader.i = CkJsonObject::ckCreate()
    If recipHeader.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckUpdateString(recipHeader,"kid","recipient-key-1")
    success = CkJwe::ckSetRecipientHeader(jwe,0,recipHeader)
    If success = 0
        Debug CkJwe::ckLastErrorText(jwe)
        CkJwe::ckDispose(jwe)
        CkJsonObject::ckDispose(header)
        CkJsonObject::ckDispose(recipHeader)
        ProcedureReturn
    EndIf

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

    CkStringBuilder::ckAppend(sbContent,"This is the secret content.")
    sbJwe.i = CkStringBuilder::ckCreate()
    If sbJwe.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJwe::ckEncryptSb(jwe,sbContent,"utf-8",sbJwe)
    If success = 0
        Debug CkJwe::ckLastErrorText(jwe)
        CkJwe::ckDispose(jwe)
        CkJsonObject::ckDispose(header)
        CkJsonObject::ckDispose(recipHeader)
        CkStringBuilder::ckDispose(sbContent)
        CkStringBuilder::ckDispose(sbJwe)
        ProcedureReturn
    EndIf

    Debug CkStringBuilder::ckGetAsString(sbJwe)


    CkJwe::ckDispose(jwe)
    CkJsonObject::ckDispose(header)
    CkJsonObject::ckDispose(recipHeader)
    CkStringBuilder::ckDispose(sbContent)
    CkStringBuilder::ckDispose(sbJwe)


    ProcedureReturn
EndProcedure