(CkPython) JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

This example duplicates the example A.3 in RFC 7516 for JSON Web Encryption (JWE).

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.

plaintext = "Live long and prosper."

jwe = chilkat.CkJwe()

# First build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256"}
jweProtHdr = chilkat.CkJsonObject()
jweProtHdr.AppendString("alg","A128KW")
jweProtHdr.AppendString("enc","A128CBC-HS256")
jwe.SetProtectedHeader(jweProtHdr)

print("JWE Protected Header: " + jweProtHdr.emit())
print("--")

# The example A.3 in RFC 7516 uses the following 128-bit AES key,
# specified in JWK (JSON Web Key) format:
#      {"kty":"oct",
#       "k":"GawgguFyGrWKav7AX4VKUg"
#      }
# This is just a way of saying: The key type ("kty") is 
# a bunch of octets ("k") in base64url encoding.
# We can simply set the AES wrapping key like this:
aesWrappingKey = "GawgguFyGrWKav7AX4VKUg"
jwe.SetWrappingKey(0,aesWrappingKey,"base64url")

# Encrypt and return the JWE:
strJwe = jwe.encrypt(plaintext,"utf-8")
if (jwe.get_LastMethodSuccess() != True):
    print(jwe.lastErrorText())
    sys.exit()

# Show the JWE we just created:
print(strJwe)

# Decrypt the JWE that was just produced.
# 1) Load the JWE.
# 2) Set the AES wrapping key.
# 3) Decrypt.
jwe2 = chilkat.CkJwe()
success = jwe2.LoadJwe(strJwe)
if (success != True):
    print(jwe2.lastErrorText())
    sys.exit()

# Set the AES wrap key.
jwe2.SetWrappingKey(0,aesWrappingKey,"base64url")

# Decrypt.
originalPlaintext = jwe2.decrypt(0,"utf-8")
if (jwe2.get_LastMethodSuccess() != True):
    print(jwe2.lastErrorText())
    sys.exit()

print("original text: ")
print(originalPlaintext)

# ---------------------------------------------------------------------------------
# It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.3.7
# because it was produced using the same AES Wrap key.

sbJwe = chilkat.CkStringBuilder()
sbJwe.Append("eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.")
sbJwe.Append("6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.")
sbJwe.Append("AxY8DCtDaGlsbGljb3RoZQ.")
sbJwe.Append("KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.")
sbJwe.Append("U0m_YmjN04DJvceFICbCVQ")

success = jwe2.LoadJweSb(sbJwe)
if (success != True):
    print(jwe2.lastErrorText())
    sys.exit()

jwe2.SetWrappingKey(0,aesWrappingKey,"base64url")

# Decrypt.
originalPlaintext = jwe2.decrypt(0,"utf-8")
if (jwe2.get_LastMethodSuccess() != True):
    print(jwe2.lastErrorText())
    sys.exit()

print(originalPlaintext)