CkPython

JWE using PBES2 Key Wrapping

See more JSON Web Encryption (JWE) Examples

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.

CkPython

import sys
import chilkat

success = False

# 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..
jweProtHdr = chilkat.CkJsonObject()
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 = chilkat.CkPrng()
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.get_LastMethodSuccess() != True):
    print(jwe.lastErrorText())
    sys.exit()

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

# Decrypt the JWE.
jwe2 = chilkat.CkJwe()
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.get_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.