(Ruby) 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 Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require '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.new()
jweProtHdr.AppendString("alg","RSA-OAEP")
jweProtHdr.AppendString("enc","A256GCM")
print "JWE Protected Header: " + jweProtHdr.emit() + "\n";
print "--" + "\n";

# ---------------------------------
# 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.new()
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.new()
success = rsaPrivKey.LoadJwk(sbJwk.getAsString())
if (success != true)
    print rsaPrivKey.lastErrorText() + "\n";
    exit
end

# 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.new()
jwe.SetProtectedHeader(jweProtHdr)
jwe.SetPublicKey(0,rsaPubKey)

strJwe = jwe.encrypt(plaintext,"utf-8")
if (jwe.get_LastMethodSuccess() != true)
    print jwe.lastErrorText() + "\n";
    exit
end

# 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 + "\n";

# 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.new()
success = jwe2.LoadJwe(strJwe)
if (success != true)
    print jwe2.lastErrorText() + "\n";
    exit
end

# 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() + "\n";
    exit
end

print "original text: " + "\n";
print originalPlaintext + "\n";

# ---------------------------------------------------------------------------------
# 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.new()
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() + "\n";
    exit
end

# 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() + "\n";
    exit
end

print originalPlaintext + "\n";