Lianja

Sign a JWS with an HMAC Key

See more JSON Web Signatures (JWS) Examples

Demonstrates Jws.SetMacKey, which sets the symmetric MAC key for a signature. The key bytes are supplied in a named encoding such as hex or base64.

Background. HMAC-based JWS (for example HS256) authenticates the payload with a shared symmetric key that both signer and verifier possess.

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llSuccess = .F.

loJws = createobject("CkJws")

//  Protected header specifying HMAC-SHA256.
loHeader = createobject("CkJsonObject")
loHeader.UpdateString("alg","HS256")
llSuccess = loJws.SetProtectedHeader(0,loHeader)
if (llSuccess = .F.) then
    ? loJws.LastErrorText
    release loJws
    release loHeader
    return
endif

llBIncludeBom = .F.
llSuccess = loJws.SetPayload("This is the content to sign.","utf-8",llBIncludeBom)
if (llSuccess = .F.) then
    ? loJws.LastErrorText
    release loJws
    release loHeader
    return
endif

//  Set the symmetric MAC key for signature 0.  The key bytes are provided in the named encoding (here
//  base64).  In production, obtain the key from a secure source rather than hard-coding it.
lcBase64Key = "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU="
llSuccess = loJws.SetMacKey(0,lcBase64Key,"base64")
if (llSuccess = .F.) then
    ? loJws.LastErrorText
    release loJws
    release loHeader
    return
endif

lcJwsCompact = loJws.CreateJws()
if (loJws.LastMethodSuccess = .F.) then
    ? loJws.LastErrorText
    release loJws
    release loHeader
    return
endif

? lcJwsCompact


release loJws
release loHeader