(Chilkat2-Python) JWE using PBES2 Key Wrapping

Demonstrates how to create and decrypt a JWE that using PBES2 key wrapping.

This example demonstrates PBES2 with HMAC SHA-256 and A128KW wrapping. It is also possible to do the following by simply changing the "alg" parameter:

• PBES2 with HMAC SHA-384 and A192KW wrapping
• PBES2 with HMAC SHA-512 and A256KW wrapping

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

Chilkat2 Python Downloads install with pip pip3 install chilkat2 or download... Python Module for Windows, Linux, Alpine Linux, MacOS, Solaris

import sys
import chilkat2

# 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 = chilkat2.Jwe()

# First build the JWE Protected Header..
jweProtHdr = chilkat2.JsonObject()
jweProtHdr.AppendString("alg","PBES2-HS256+A128KW")
jweProtHdr.AppendString("enc","A128GCM")

# PBES2 requires two additional parameters:
# 1) A random salt parameter ("p2s") containing 8 or more bytes in base64url format.
# 2) An iteration count parameter ("p2c").  A minimum count of 1000 is recommended.
#    The iteration count is intended to make the PBES2 computation more expensive (time consuming)
#    to prevent brute-force attacks.
prng = chilkat2.Prng()
jweProtHdr.AppendString("p2s",prng.GenRandom(16,"base64url"))
jweProtHdr.AppendString("p2c","1000")

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

# Don't forget to actually provide the protected header to the JWE object:
jwe.SetProtectedHeader(jweProtHdr)

# Set the PBES2 password
recipientIndex = 0
jwe.SetPassword(recipientIndex,"top secret")

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

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

# Decrypt the JWE.
jwe2 = chilkat2.Jwe()
success = jwe2.LoadJwe(strJwe)
if (success != True):
    print(jwe2.LastErrorText)
    sys.exit()

# Set the PBES2 password
jwe2.SetPassword(recipientIndex,"top secret")

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

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

# Sample output:

# JWE Protected Header: {"alg":"PBES2-HS256+A128KW","enc":"A128GCM","p2s":"z39rTEfRy1T1Yn_D1mZRlg","p2c":"1000"}
# --
# eyJhbGciOiJQQkVTMi1IUzI1NitBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIiwicDJzIjoiejM5clRFZlJ5MVQxWW5fRDFtWlJsZyIsInAyYyI6IjEwMDAifQ.koYt6PrFmYwcwdcT7ZcvXHA1d-Xez5h4.luGlbvEnZp-7IsBOj42Yhw.YMTcfLf8Qe4zazozGV2OAu3cUdQ8Kg.rWub47ESWkc6IqZJTvSTmg
# original text: 
# Live long and prosper.