(CkPython) Create a JWS Using ECDSA P-256 SHA-256

Creates and validates a JSON Web Signature (JWS) that uses ECDSA P-256 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.

# Use the following ECC key loaded from JWK format.
sbJwk = chilkat.CkStringBuilder()
sbJwk.Append("{\"kty\":\"EC\",")
sbJwk.Append("\"crv\":\"P-256\",")
sbJwk.Append("\"x\":\"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU\",")
sbJwk.Append("\"y\":\"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0\",")
sbJwk.Append("\"d\":\"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI\"")
sbJwk.Append("}")

eccKey = chilkat.CkPrivateKey()
# Note: This example loads the ECDSA key from JWK format.  Any format can be loaded
# into the private key object. (See the online reference documentation..)
success = eccKey.LoadJwk(sbJwk.getAsString())
if (success != True):
    print(eccKey.lastErrorText())
    sys.exit()

# Create the JWS Protected Header
jwsProtHdr = chilkat.CkJsonObject()
jwsProtHdr.AppendString("alg","ES256")

jws = chilkat.CkJws()

# Set the protected header:
signatureIndex = 0
jws.SetProtectedHeader(signatureIndex,jwsProtHdr)

# Set the ECC key:
jws.SetPrivateKey(signatureIndex,eccKey)

# 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)

# Note: ECC signatures use random values, so the output will be different each time a signature is produced.
# sample output:
# JWS: eyJhbGciOiJFUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.J6EGTNkeuEjehHHBu0SOKzifm8r35wbx49A5964pxzB7gannyZZPMkK7vmlaPJ-K8Xmm8cZsQySAPC12Xd8avw

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

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

# eccPubKey is a CkPublicKey
eccPubKey = eccKey.GetPublicKey()

# Set the ECC public key used for validation.
signatureIndex = 0
jws2.SetPublicKey(signatureIndex,eccPubKey)

# 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 ECC 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:
# { 
#   "alg": "ES256"
# }