CkPython

JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

See more JSON Web Encryption (JWE) Examples

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.

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: {"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)