B4X Requires Chilkat v11.0.0+

Validate JWS Using RSASSA-PKCS1-v1_5 SHA-256

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) that uses RSASSA-PKCS1-v1_5 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.

'  This example takes a JSON signature in compact serialization format,
'  and uses an RSA public key to validate and recover the protected header and payload.

'  We only need a public key for signature validation.  This is the RSA public key
'  that is used:

'       {"kty":"RSA", 
'        "n":"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx
'             HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs
'             D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH
'             SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV
'             MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8
'             NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ", 
'        "e":"AQAB"
'       }

Dim sbPubKey As ChilkatStringBuilder
sbPubKey.Initialize
sbPubKey.Append("{" & Chr(34) & "kty" & Chr(34) & ":" & Chr(34) & "RSA" & Chr(34) & ",")
sbPubKey.Append(Chr(34) & "n" & Chr(34) & ":" & Chr(34) & "ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx")
sbPubKey.Append("HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs")
sbPubKey.Append("D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH")
sbPubKey.Append("SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV")
sbPubKey.Append("MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8")
sbPubKey.Append("NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ" & Chr(34) & ",")
sbPubKey.Append(Chr(34) & "e" & Chr(34) & ":" & Chr(34) & "AQAB" & Chr(34))
sbPubKey.Append("}")

Dim pubKey As ChilkatPublicKey
pubKey.Initialize
success = pubKey.LoadFromString(sbPubKey.GetAsString)
If success = False Then
    Log(pubKey.LastErrorText)
    Return
End If


Dim jws As ChilkatJws
jws.Initialize

'  Set the RSA public key:
Dim signatureIndex As Int = 0
jws.SetPublicKey(signatureIndex, pubKey)

'  Load the JWS.
Dim sbJws As ChilkatStringBuilder
sbJws.Initialize
sbJws.Append("eyJhbGciOiJSUzI1NiJ9")
sbJws.Append(".")
sbJws.Append("eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt")
sbJws.Append("cGxlLmNvbS9pc19yb290Ijp0cnVlfQ")
sbJws.Append(".")
sbJws.Append("cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7")
sbJws.Append("AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4")
sbJws.Append("BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K")
sbJws.Append("0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv")
sbJws.Append("hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB")
sbJws.Append("p0igcN_IoypGlUPQGe77Rw")

success = jws.LoadJwsSb(sbJws)
If success = False Then
    Log(jws.LastErrorText)
    Return
End If


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

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


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

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

'  Examine the protected header:

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

joseHeader.EmitCompact = False

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

'  Output:

'  	Signature validated.
'  	--
'  	Recovered content:
'  	{"iss":"joe", 
'  	 "exp":1300819380,
'  	 "http://example.com/is_root":true}
'  	--
'  	Protected (JOSE) header:
'  	{ 
'  	  "alg": "RS256"
'  	}