(CkPython) JWE using RSAES-OAEP and AES GCM

This example duplicates the example A.1 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 = "The true sign of intelligence is not knowledge but imagination."

# ---------------------------------
# A.1.1 JOSE Header
# First build the JWE Protected Header.
# We want to build this: {"alg":"RSA-OAEP","enc":"A256GCM"}
jweProtHdr = chilkat.CkJsonObject()
jweProtHdr.AppendString("alg","RSA-OAEP")
jweProtHdr.AppendString("enc","A256GCM")
print("JWE Protected Header: " + jweProtHdr.emit())
print("--")

# ---------------------------------
# A.1.2 Content Encryption Key
# Note: Chilkat automatically generates the random CEK internally.
# The application does not need to explicitly take this step.

# ---------------------------------
# A.1.3.  Key Encryption
# The application should load an RSA private key from any format.
# However, the application does not need to explicitly construct the JWE Encrypted Key.
# Chilkat automatically does it internally.
# The design of the Chilkat JWE API is to allow the application to create the JWE
# after specifying the inputs.  (This is in contrast to forcing the application developer
# to painstakingly go through each step of the JWE construction process.)

# The specific RSA key used in the A.1 example is the following JWK:
sbJwk = chilkat.CkStringBuilder()
sbJwk.Append("{\"kty\": \"RSA\",")
sbJwk.Append("\"n\": \"oahUIoWw0K0usKNuOR6H4wkf4oBUXHTxRvgb48E-BVvxkeDNjbC4he8rUW")
sbJwk.Append("cJoZmds2h7M70imEVhRU5djINXtqllXI4DFqcI1DgjT9LewND8MW2Krf3S")
sbJwk.Append("psk_ZkoFnilakGygTwpZ3uesH-PFABNIUYpOiN15dsQRkgr0vEhxN92i2a")
sbJwk.Append("sbOenSZeyaxziK72UwxrrKoExv6kc5twXTq4h-QChLOln0_mtUZwfsRaMS")
sbJwk.Append("tPs6mS6XrgxnxbWhojf663tuEQueGC-FCMfra36C9knDFGzKsNa7LZK2dj")
sbJwk.Append("YgyD3JR_MB_4NUJW_TqOQtwHYbxevoJArm-L5StowjzGy-_bq6Gw\",")
sbJwk.Append("\"e\": \"AQAB\",")
sbJwk.Append("\"d\": \"kLdtIj6GbDks_ApCSTYQtelcNttlKiOyPzMrXHeI-yk1F7-kpDxY4-WY5N")
sbJwk.Append("WV5KntaEeXS1j82E375xxhWMHXyvjYecPT9fpwR_M9gV8n9Hrh2anTpTD9")
sbJwk.Append("3Dt62ypW3yDsJzBnTnrYu1iwWRgBKrEYY46qAZIrA2xAwnm2X7uGR1hghk")
sbJwk.Append("qDp0Vqj3kbSCz1XyfCs6_LehBwtxHIyh8Ripy40p24moOAbgxVw3rxT_vl")
sbJwk.Append("t3UVe4WO3JkJOzlpUf-KTVI2Ptgm-dARxTEtE-id-4OJr0h-K-VFs3VSnd")
sbJwk.Append("VTIznSxfyrj8ILL6MG_Uv8YAu7VILSB3lOW085-4qE3DzgrTjgyQ\",")
sbJwk.Append("\"p\": \"1r52Xk46c-LsfB5P442p7atdPUrxQSy4mti_tZI3Mgf2EuFVbUoDBvaRQ-")
sbJwk.Append("SWxkbkmoEzL7JXroSBjSrK3YIQgYdMgyAEPTPjXv_hI2_1eTSPVZfzL0lf")
sbJwk.Append("fNn03IXqWF5MDFuoUYE0hzb2vhrlN_rKrbfDIwUbTrjjgieRbwC6Cl0\",")
sbJwk.Append("\"q\": \"wLb35x7hmQWZsWJmB_vle87ihgZ19S8lBEROLIsZG4ayZVe9Hi9gDVCOBm")
sbJwk.Append("UDdaDYVTSNx_8Fyw1YYa9XGrGnDew00J28cRUoeBB_jKI1oma0Orv1T9aX")
sbJwk.Append("IWxKwd4gvxFImOWr3QRL9KEBRzk2RatUBnmDZJTIAfwTs0g68UZHvtc\",")
sbJwk.Append("\"dp\": \"ZK-YwE7diUh0qR1tR7w8WHtolDx3MZ_OTowiFvgfeQ3SiresXjm9gZ5KL")
sbJwk.Append("hMXvo-uz-KUJWDxS5pFQ_M0evdo1dKiRTjVw_x4NyqyXPM5nULPkcpU827")
sbJwk.Append("rnpZzAJKpdhWAgqrXGKAECQH0Xt4taznjnd_zVpAmZZq60WPMBMfKcuE\",")
sbJwk.Append("\"dq\": \"Dq0gfgJ1DdFGXiLvQEZnuKEN0UUmsJBxkjydc3j4ZYdBiMRAy86x0vHCj")
sbJwk.Append("ywcMlYYg4yoC4YZa9hNVcsjqA3FeiL19rk8g6Qn29Tt0cj8qqyFpz9vNDB")
sbJwk.Append("UfCAiJVeESOjJDZPYHdHY8v1b-o-Z2X5tvLx-TCekf7oxyeKDUqKWjis\",")
sbJwk.Append("\"qi\": \"VIMpMYbPf47dT1w_zDUXfPimsSegnMOA1zTaX7aGk_8urY6R8-ZW1FxU7")
sbJwk.Append("AlWAyLWybqq6t16VFd7hQd0y6flUK4SlOydB61gwanOsXGOAOv82cHq0E3")
sbJwk.Append("eL4HrtZkUuKvnPrMnsUUFlfUdybVzxyjz9JF_XyaY14ardLSjf4L_FNY\"}")

# Load this JWK into a Chilkat private key object.
rsaPrivKey = chilkat.CkPrivateKey()
success = rsaPrivKey.LoadJwk(sbJwk.getAsString())
if (success != True):
    print(rsaPrivKey.lastErrorText())
    sys.exit()

# The public key is used to encrypt (i.e. create the JWE), 
# and the private key is used to decrypt.
# The RSA public key is simply a subset of the private key.  The RSA public key
# is composed of the "n" and "e" members shown above.  These are also known as the
# modulus and exponent.
# We can simply get the public key object from the private key object
# rsaPubKey is a CkPublicKey
rsaPubKey = rsaPrivKey.GetPublicKey()

# ---------------------------------
# A.1.4.  Initialization Vector
# Chilkat automatically generates the necessary random IV internally.  
# The application does not need to do this explicitly.

# ---------------------------------
# A.1.5.  Additional Authenticated Data
# The Additional Authenticated Data encryption parameter is
# ASCII(BASE64URL(UTF8(JWE Protected Header))).
# Again, Chilkat automatically takes care of this internally.
# The application does not need to explicitly take this step.

# ---------------------------------
# A.1.6.  Content Encryption
# Again... this step is handled by Chilkat internally.

# ---------------------------------
# A.1.7.  Complete Representation
# The application need only call the Encrypt, EncryptSb, or EncryptBd method
# return the fully assembled JWE.  
# The final representation in the Compact Serialization 
# is the string BASE64URL(UTF8(JWE Protected Header)) || '.' ||
# BASE64URL(JWE Encrypted Key) || '.' || BASE64URL(JWE Initialization
# Vector) || '.' || BASE64URL(JWE Ciphertext) || '.' || BASE64URL(JWE
# Authentication Tag).

jwe = chilkat.CkJwe()
jwe.SetProtectedHeader(jweProtHdr)
jwe.SetPublicKey(0,rsaPubKey)

strJwe = jwe.encrypt(plaintext,"utf-8")
if (jwe.get_LastMethodSuccess() != True):
    print(jwe.lastErrorText())
    sys.exit()

# Note: The RSA OAEP algorithm uses random padding bytes internally.
# Therefore, the results will appear different each time -- even if the
# identical plaintext is encrypted with the identical RSA key. 
# (Do not expect the appearance of the results to be the same as what
# is published in the RFC.  However, what is published in the RFC *should*
# be decryptable using the code that follows.)
print(strJwe)

# Let's decrypt the JWE that was just produced.
# Do the following to decrypt a JWE:
# 1) Load the JWE.
# 2) Set the private key for decryption.
# 3) Decrypt.
jwe2 = chilkat.CkJwe()
success = jwe2.LoadJwe(strJwe)
if (success != True):
    print(jwe2.lastErrorText())
    sys.exit()

# Provide the RSA private key for decryption.
# (The JWE was encrypted for a single recipient at index 0.)
jwe2.SetPrivateKey(0,rsaPrivKey)

# 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.1.7
# because it was produced using the same RSA key.

sbJwe = chilkat.CkStringBuilder()
sbJwe.Append("eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.")
sbJwe.Append("OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe")
sbJwe.Append("ipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDb")
sbJwe.Append("Sv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaV")
sbJwe.Append("mqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je8")
sbJwe.Append("1860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi")
sbJwe.Append("6UklfCpIMfIjf7iGdXKHzg.")
sbJwe.Append("48V1_ALb6US04U3b.")
sbJwe.Append("5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6ji")
sbJwe.Append("SdiwkIr3ajwQzaBtQD_A.")
sbJwe.Append("XFBoMYUZodetZdvTiFvSkQ")

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

# Provide the RSA private key for decryption.
jwe2.SetPrivateKey(0,rsaPrivKey)

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

print(originalPlaintext)