(Ruby) JWE with Binary Data

Demonstrates how to create a JWE that contains a binary payload (such as a JPG image).

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.

# Load a JPG file that will be the JWE payload.
jpgBytes = Chilkat::CkBinData.new()
success = jpgBytes.LoadFile("qa_data/jpg/starfish.jpg")
# Make sure your app checks the success/failure of the call to LoadFile..
print "Original JPG size = " + jpgBytes.get_NumBytes().to_s() + "\n";

jwe = Chilkat::CkJwe.new()

jweProtHdr = Chilkat::CkJsonObject.new()
jweProtHdr.AppendString("alg","A128KW")
jweProtHdr.AppendString("enc","A128CBC-HS256")
jwe.SetProtectedHeader(jweProtHdr)

aesWrappingKey = "GawgguFyGrWKav7AX4VKUg"
jwe.SetWrappingKey(0,aesWrappingKey,"base64url")

# Encrypt and return the JWE in sbJwe:
sbJwe = Chilkat::CkStringBuilder.new()
success = jwe.EncryptBd(jpgBytes,sbJwe)
if (success != true)
    print jwe.lastErrorText() + "\n";
    exit
end

# Show the JWE:
print sbJwe.getAsString() + "\n";
print "size of JWE: " + sbJwe.get_Length().to_s() + "\n";

# ---------------------------------------------------------
# Decrypt to get the original JPG file..

jwe2 = Chilkat::CkJwe.new()
success = jwe2.LoadJweSb(sbJwe)
if (success != true)
    print jwe2.lastErrorText() + "\n";
    exit
end

# Set the AES wrap key.
jwe2.SetWrappingKey(0,aesWrappingKey,"base64url")

# Decrypt.
jpgOriginal = Chilkat::CkBinData.new()
success = jwe2.DecryptBd(0,jpgOriginal)
if (success != true)
    print jwe2.lastErrorText() + "\n";
    exit
end

print "Decrypted JPG size = " + jpgOriginal.get_NumBytes().to_s() + "\n";

# Save the decrypted JPG to a file.
success = jpgOriginal.WriteFile("qa_output/jwe_decrypted_starfish.jpg")

print "success = " + success.to_s() + "\n";

# The output of this program, when tested, was:
# Original JPG size = 6229
# eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.9YFz_wteV ... 7Et3hKhpxnKEXw
# size of JWE: 8473
# Decrypted JPG size = 6229
# success = True