(CkPython) Validate JWS with Multiple Signatures using the General JSON Serialization Format

Validates and recovers data and headers from a JSON Web Signature (JWS) containing 3 signatures.

Note: Chilkat supports all of the following JWS algorithms:

   +--------------+-------------------------------+--------------------+
   | "alg" Param  | Digital Signature or MAC      | Implementation     |
   | Value        | Algorithm                     | Requirements       |
   +--------------+-------------------------------+--------------------+
   | HS256        | HMAC using SHA-256            | Required           |
   | HS384        | HMAC using SHA-384            | Optional           |
   | HS512        | HMAC using SHA-512            | Optional           |
   | RS256        | RSASSA-PKCS1-v1_5 using       | Recommended        |
   |              | SHA-256                       |                    |
   | RS384        | RSASSA-PKCS1-v1_5 using       | Optional           |
   |              | SHA-384                       |                    |
   | RS512        | RSASSA-PKCS1-v1_5 using       | Optional           |
   |              | SHA-512                       |                    |
   | ES256        | ECDSA using P-256 and SHA-256 | Recommended+       |
   | ES384        | ECDSA using P-384 and SHA-384 | Optional           |
   | ES512        | ECDSA using P-521 and SHA-512 | Optional           |
   | PS256        | RSASSA-PSS using SHA-256 and  | Optional           |
   |              | MGF1 with SHA-256             |                    |
   | PS384        | RSASSA-PSS using SHA-384 and  | Optional           |
   |              | MGF1 with SHA-384             |                    |
   | PS512        | RSASSA-PSS using SHA-512 and  | Optional           |
   |              | MGF1 with SHA-512             |                    |
   +--------------+-------------------------------+--------------------+

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, prepare the public keys that will be needed for each signature.

# ---------------------------------------------------
# Use the following RSA key loaded from JWK format.
sbRsaJwk = chilkat.CkStringBuilder()
sbRsaJwk.Append("{\"kty\":\"RSA\",")
sbRsaJwk.Append("\"n\":\"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx")
sbRsaJwk.Append("HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs")
sbRsaJwk.Append("D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH")
sbRsaJwk.Append("SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV")
sbRsaJwk.Append("MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8")
sbRsaJwk.Append("NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ\",")
sbRsaJwk.Append("\"e\":\"AQAB\"")
sbRsaJwk.Append("}")

rsaKey = chilkat.CkPublicKey()
success = rsaKey.LoadFromString(sbRsaJwk.getAsString())
if (success != True):
    print(rsaKey.lastErrorText())
    sys.exit()

# ---------------------------------------------------
# Use the following ECC public key loaded from JWK format.
sbEccJwk = chilkat.CkStringBuilder()
sbEccJwk.Append("{\"kty\":\"EC\",")
sbEccJwk.Append("\"crv\":\"P-256\",")
sbEccJwk.Append("\"x\":\"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU\",")
sbEccJwk.Append("\"y\":\"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0\"")
sbEccJwk.Append("}")

eccKey = chilkat.CkPublicKey()
success = eccKey.LoadFromString(sbEccJwk.getAsString())
if (success != True):
    print(eccKey.lastErrorText())
    sys.exit()

# ---------------------------------------------------
# The HMAC key (in base64url format)
hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"

# The code below will verify each of the signatures in this JWS:

# { 
#   "payload": "SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu",
#   "signatures": [
#     { 
#       "protected": "eyJhbGciOiJSUzI1NiIsImtpZCI6Im15UnNhS2V5In0",
#       "signature": "IPMQ02niTQDwLzsRZSCaEm9VEyAX_AVe3HWjniNt9kW-a8d6ZVbd2k6jGae8s1yIh0cgxDnXQ6-p6_sBI0cnMO0xpuJANhh2vFtNJl5lisad94-H3mB3lSfafRqxeYp5D8bh39BPv7y3PrUNVMQdKEJp_D5oJ0ROPTIYx3EG8eJQOx1HO0KqhcUo401XR6KSsIyFm5joBLNKTVzxZUTT1RRZZtwTdeZkbGevugIOX_9gHAtARpV6WaFA4Vvjnq8X9wPgqjWNCQRupadhTPz0JAsa-wy5vXQjsFlXAn43mDPpMfna5Ab3F5pS4yDwkbX6nRn7XBxH1SnnNJRFholQZw"
#     },
#     { 
#       "protected": "eyJhbGciOiJFUzI1NiIsImtpZCI6Im15RWNLZXkifQ",
#       "signature": "1OQtaT3pgZmkDxvlfghvxL_8kX16WIen6u1MadEq1pA4qytA0--_EwZDNk00GDPWFpoJtKznibMZzLOg_UhHIw"
#     },
#     { 
#       "protected": "eyJhbGciOiJIUzI1NiIsImtpZCI6Im15TWFjS2V5In0",
#       "signature": "YY8yVjmJJfy7YJOn3uUydG8WCY2PEuCvOLil5Ks5lnw"
#     }
#   ]
# }

sbJws = chilkat.CkStringBuilder()
sbJws.Append("{ ")
sbJws.Append("  \"payload\": \"SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu\",")
sbJws.Append("  \"signatures\": [")
sbJws.Append("    { ")
sbJws.Append("      \"protected\": \"eyJhbGciOiJSUzI1NiIsImtpZCI6Im15UnNhS2V5In0\",")
sbJws.Append("      \"signature\": \"IPMQ02niTQDwLzsRZSCaEm9VEyAX_AVe3HWjniNt9kW-a8d6ZVbd2k6jGae8s1yIh0cgxDnXQ6-p6_sBI0cnMO0xpuJANhh2vFtNJl5lisad94-H3mB3lSfafRqxeYp5D8bh39BPv7y3PrUNVMQdKEJp_D5oJ0ROPTIYx3EG8eJQOx1HO0KqhcUo401XR6KSsIyFm5joBLNKTVzxZUTT1RRZZtwTdeZkbGevugIOX_9gHAtARpV6WaFA4Vvjnq8X9wPgqjWNCQRupadhTPz0JAsa-wy5vXQjsFlXAn43mDPpMfna5Ab3F5pS4yDwkbX6nRn7XBxH1SnnNJRFholQZw\"")
sbJws.Append("    },")
sbJws.Append("    { ")
sbJws.Append("      \"protected\": \"eyJhbGciOiJFUzI1NiIsImtpZCI6Im15RWNLZXkifQ\",")
sbJws.Append("      \"signature\": \"1OQtaT3pgZmkDxvlfghvxL_8kX16WIen6u1MadEq1pA4qytA0--_EwZDNk00GDPWFpoJtKznibMZzLOg_UhHIw\"")
sbJws.Append("    },")
sbJws.Append("    { ")
sbJws.Append("      \"protected\": \"eyJhbGciOiJIUzI1NiIsImtpZCI6Im15TWFjS2V5In0\",")
sbJws.Append("      \"signature\": \"YY8yVjmJJfy7YJOn3uUydG8WCY2PEuCvOLil5Ks5lnw\"")
sbJws.Append("    }")
sbJws.Append("  ]")
sbJws.Append("}")

jws = chilkat.CkJws()

success = jws.LoadJwsSb(sbJws)
if (success != True):
    print(jws.lastErrorText())
    sys.exit()

# The payload is easily accessible:
print("Payload: " + jws.getPayload("utf-8"))

sbKeyId = chilkat.CkStringBuilder()
bCaseSensitive = False

numSignatures = jws.get_NumSignatures()
i = 0
while i < numSignatures :
    # protHeader is a CkJsonObject
    protHeader = jws.GetProtectedHeader(i)

    print("--------------------------")
    print(str(i) + ": ")

    # Get the protected header.
    protHeader.put_EmitCompact(False)
    print(protHeader.emit())

    # Get the key ID ("kid") member.

    # Note: In this example, the "kid" values are contained in the protected headers.
    # They could've just as easily been located in unprotected headers.  In that case,
    # we would've called GetUnprotectedHeader(i) instead of GetProtectedHeader(i).

    sbKeyId.Clear()
    sbKeyId.Append(protHeader.stringOf("kid"))

    # Set the key based on key ID.
    if (sbKeyId.ContentsEqual("myRsaKey",bCaseSensitive) == True):
        jws.SetPublicKey(i,rsaKey)

    if (sbKeyId.ContentsEqual("myEcKey",bCaseSensitive) == True):
        jws.SetPublicKey(i,eccKey)

    if (sbKeyId.ContentsEqual("myMacKey",bCaseSensitive) == True):
        jws.SetMacKey(i,hmacKey,"base64url")

    # Validate this signature.
    v = jws.Validate(i)
    if (v < 0):
        # Perhaps Chilkat was not unlocked or the trial expired..
        print("Validate failed for some other reason.")
        print(jws.lastErrorText())
    else:
        if (v == 0):
            print("Invalid signature.  The key was incorrect, the JWS was invalid, or both.")
        else:
            print("Signature validated.")

    i = i + 1

# The output of this program is:

# 	Payload: In our village, folks say God crumbles up the old moon into stars.
# 	--------------------------
# 	0: 
# 	{
# 	  "alg": "RS256",
# 	  "kid": "myRsaKey"
# 	}
# 
# 	Signature validated.
# 	--------------------------
# 	1: 
# 	{
# 	  "alg": "ES256",
# 	  "kid": "myEcKey"
# 	}
# 
# 	Signature validated.
# 	--------------------------
# 	2: 
# 	{
# 	  "alg": "HS256",
# 	  "kid": "myMacKey"
# 	}
# 
# 	Signature validated.