B4X Requires Chilkat v11.0.0+

JWS Using HMAC SHA-256

See more JSON Web Signatures (JWS) Examples

Creates a JSON Web Signatures (JWS) using HMAC SHA-256. B4X

Dim success As Boolean = False

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

'  First create the JWS Protected Header
Dim jwsProtHdr As ChilkatJsonObject
jwsProtHdr.Initialize
jwsProtHdr.AppendString("typ", "JWT")
jwsProtHdr.AppendString("alg", "HS256")
Log("JWS Protected Header: " & jwsProtHdr.Emit)

'  Output:
'  JWS Protected Header: {"typ":"JWT","alg":"HS256"}

Dim jws As ChilkatJws
jws.Initialize

'  Set the HMAC key:
Dim hmacKey As String = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
Dim signatureIndex As Int = 0
jws.SetMacKey(signatureIndex, hmacKey, "base64url")

'  Set the protected header:
jws.SetProtectedHeader(signatureIndex, jwsProtHdr)

'  Set the payload.
Dim bIncludeBom As Boolean = False
Dim payloadStr As String = "In our village, folks say God crumbles up the old moon into stars."
jws.SetPayload(payloadStr, "utf-8", bIncludeBom)

'  Create the JWS
'  By default, the compact serialization is used.
Dim jwsCompact As String = jws.CreateJws
If jws.LastMethodSuccess = False Then
    Log(jws.LastErrorText)
    Return
End If


Log("JWS: " & jwsCompact)

'  sample output:
'  JWS: eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.bsYsi8HJ0N6OqGI1hKQ9QQRNPxxA5qMpcHLtOvXatk8

'  Now load the JWS, validate, and recover the original text.
Dim jws2 As ChilkatJws
jws2.Initialize

'  Load the JWS.
success = jws2.LoadJws(jwsCompact)

'  Set the MAC key used for validation.
signatureIndex = 0
jws2.SetMacKey(signatureIndex, hmacKey, "base64url")

'  Validate the 1st (and only) signature at index 0..
Dim v As Int = jws2.Validate(signatureIndex)
If v < 0 Then
    '  Perhaps Chilkat was not unlocked or the trial expired..
    Log("Method call failed for some other reason.")
    Log(jws2.LastErrorText)
    Return
End If

If v = 0 Then
    Log("Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.")
    Return
End If


'  If we get here, the signature was validated..
Log("Signature validated.")

'  Recover the original content:
Log(jws2.GetPayload("utf-8"))

'  Examine the protected header:

Dim joseHeader As ChilkatJsonObject
joseHeader.Initialize
success = jws2.GetProtectedH(signatureIndex, joseHeader)
If success = False Then
    Log(jws2.LastErrorText)
    Return
End If


joseHeader.EmitCompact = False

Log("Protected (JOSE) header:")
Log(joseHeader.Emit)

'  Output:

'  	Signature validated.
'  	In our village, folks say God crumbles up the old moon into stars.
'  	Protected (JOSE) header:
'  	{ 
'  	  "typ": "JWT",
'  	  "alg": "HS256"
'  	}