(Ruby) JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

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.

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 = "Live long and prosper."

jwe = Chilkat::CkJwe.new()

# First build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256"}
jweProtHdr = Chilkat::CkJsonObject.new()
jweProtHdr.AppendString("alg","A128KW")
jweProtHdr.AppendString("enc","A128CBC-HS256")
jwe.SetProtectedHeader(jweProtHdr)

print "JWE Protected Header: " + jweProtHdr.emit() + "\n";
print "--" + "\n";

# 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() + "\n";
    exit
end

# Show the JWE we just created:
print strJwe + "\n";

# Decrypt the JWE that was just produced.
# 1) Load the JWE.
# 2) Set the AES wrapping key.
# 3) Decrypt.
jwe2 = Chilkat::CkJwe.new()
success = jwe2.LoadJwe(strJwe)
if (success != true)
    print jwe2.lastErrorText() + "\n";
    exit
end

# 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() + "\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.3.7
# because it was produced using the same AES Wrap key.

sbJwe = Chilkat::CkStringBuilder.new()
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() + "\n";
    exit
end

jwe2.SetWrappingKey(0,aesWrappingKey,"base64url")

# Decrypt.
originalPlaintext = jwe2.decrypt(0,"utf-8")
if (jwe2.get_LastMethodSuccess() != true)
    print jwe2.lastErrorText() + "\n";
    exit
end

print originalPlaintext + "\n";