(CkPython) JWS Using HMAC SHA-256

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

Note: This example requires Chilkat v9.5.0.66 or greater.

Chilkat Python Downloads install with pip pip3 install chilkat or download... Python Module for Windows, MacOS, Linux, Alpine Linux, Solaris

import sys
import chilkat

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

# Note: This example requires Chilkat v9.5.0.66 or greater.

# First create the JWS Protected Header
jwsProtHdr = chilkat.CkJsonObject()
jwsProtHdr.AppendString("typ","JWT")
jwsProtHdr.AppendString("alg","HS256")
print("JWS Protected Header: " + jwsProtHdr.emit())

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

jws = chilkat.CkJws()

# Set the HMAC key:
hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
signatureIndex = 0
jws.SetMacKey(signatureIndex,hmacKey,"base64url")

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

# Set the payload.
bIncludeBom = False
payloadStr = "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.
jwsCompact = jws.createJws()
if (jws.get_LastMethodSuccess() != True):
    print(jws.lastErrorText())
    sys.exit()

print("JWS: " + jwsCompact)

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

# Now load the JWS, validate, and recover the original text.
jws2 = chilkat.CkJws()

# 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..
v = jws2.Validate(signatureIndex)
if (v < 0):
    # Perhaps Chilkat was not unlocked or the trial expired..
    print("Method call failed for some other reason.")
    print(jws2.lastErrorText())
    sys.exit()

if (v == 0):
    print("Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.")
    sys.exit()

# If we get here, the signature was validated..
print("Signature validated.")

# Recover the original content:
print(jws2.getPayload("utf-8"))

# Examine the protected header:
# joseHeader is a CkJsonObject
joseHeader = jws2.GetProtectedHeader(signatureIndex)
if (jws2.get_LastMethodSuccess() != True):
    print("No protected header found at the given index.")
    sys.exit()

joseHeader.put_EmitCompact(False)

print("Protected (JOSE) header:")
print(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"
# 	}