(Tcl) JWE with DEFLATE Compression

Demonstrates how to DEFLATE ("zip") compress the JWE payload prior to encryption.

Note: This example requires Chilkat v9.5.0.66 or greater.

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load ./chilkat.dll

# 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.

# Create some plaintext to be encrypted.
# This example will demonstrate with and without DEFLATE (zip) compression.
set sbPlainText [new_CkStringBuilder]

set bCrLf 1
set line "Live long and prosper."
CkStringBuilder_AppendLine $sbPlainText $line $bCrLf
CkStringBuilder_AppendLine $sbPlainText $line $bCrLf
CkStringBuilder_AppendLine $sbPlainText $line $bCrLf
CkStringBuilder_AppendLine $sbPlainText $line $bCrLf

# The text to be encrypted:
puts [CkStringBuilder_getAsString $sbPlainText]

set jwe [new_CkJwe]

# Build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256","zip":"DEF"}
# The "zip":"DEF" parameter indicates that the plaintext payload should
# be compressed prior to encryption.
set jweProtHdr [new_CkJsonObject]

CkJsonObject_AppendString $jweProtHdr "alg" "A128KW"
CkJsonObject_AppendString $jweProtHdr "enc" "A128CBC-HS256"
CkJsonObject_AppendString $jweProtHdr "zip" "DEF"
CkJwe_SetProtectedHeader $jwe $jweProtHdr

# Set the AES key wrap key:
set aesWrappingKey "GawgguFyGrWKav7AX4VKUg"
CkJwe_SetWrappingKey $jwe 0 $aesWrappingKey "base64url"

# Encrypt and return the JWE in sbJweCompressed:
set sbJweCompressed [new_CkStringBuilder]

set success [CkJwe_EncryptSb $jwe $sbPlainText "utf-8" $sbJweCompressed]
if {$success != 1} then {
    puts [CkJwe_lastErrorText $jwe]
    delete_CkStringBuilder $sbPlainText
    delete_CkJwe $jwe
    delete_CkJsonObject $jweProtHdr
    delete_CkStringBuilder $sbJweCompressed
    exit
}

# Show the compressed JWE:
puts [CkStringBuilder_getAsString $sbJweCompressed]
puts "size of compressed JWE: [CkStringBuilder_get_Length $sbJweCompressed]"

# Now create a JWE without compression.
CkJsonObject_Delete $jweProtHdr "zip"
# Make sure to update the shared protected header:
CkJwe_SetProtectedHeader $jwe $jweProtHdr

set sbJweUncompressed [new_CkStringBuilder]

set success [CkJwe_EncryptSb $jwe $sbPlainText "utf-8" $sbJweUncompressed]
if {$success != 1} then {
    puts [CkJwe_lastErrorText $jwe]
    delete_CkStringBuilder $sbPlainText
    delete_CkJwe $jwe
    delete_CkJsonObject $jweProtHdr
    delete_CkStringBuilder $sbJweCompressed
    delete_CkStringBuilder $sbJweUncompressed
    exit
}

# Show the uncompressed JWE:
puts [CkStringBuilder_getAsString $sbJweUncompressed]
puts "size of uncompressed JWE: [CkStringBuilder_get_Length $sbJweUncompressed]"

# Decrypting is the same whether compression is used or not.
# The "zip" header in the JWE indicates that the payload should be 
# automatically decompressed (inflated) after decrypting.
set jwe2 [new_CkJwe]

set success [CkJwe_LoadJweSb $jwe2 $sbJweCompressed]
if {$success != 1} then {
    puts [CkJwe_lastErrorText $jwe2]
    delete_CkStringBuilder $sbPlainText
    delete_CkJwe $jwe
    delete_CkJsonObject $jweProtHdr
    delete_CkStringBuilder $sbJweCompressed
    delete_CkStringBuilder $sbJweUncompressed
    delete_CkJwe $jwe2
    exit
}

# Set the AES wrap key.
CkJwe_SetWrappingKey $jwe2 0 $aesWrappingKey "base64url"

# Decrypt (also automatically decompresses).
set sbOriginalText [new_CkStringBuilder]

set success [CkJwe_DecryptSb $jwe2 0 "utf-8" $sbOriginalText]
if {$success != 1} then {
    puts [CkJwe_lastErrorText $jwe2]
    delete_CkStringBuilder $sbPlainText
    delete_CkJwe $jwe
    delete_CkJsonObject $jweProtHdr
    delete_CkStringBuilder $sbJweCompressed
    delete_CkStringBuilder $sbJweUncompressed
    delete_CkJwe $jwe2
    delete_CkStringBuilder $sbOriginalText
    exit
}

puts "original text from compressed JWE: "
puts [CkStringBuilder_getAsString $sbOriginalText]

# -----------------------------------------------------------
# Do the same with the uncompressed JWE

set success [CkJwe_LoadJweSb $jwe2 $sbJweUncompressed]
if {$success != 1} then {
    puts [CkJwe_lastErrorText $jwe2]
    delete_CkStringBuilder $sbPlainText
    delete_CkJwe $jwe
    delete_CkJsonObject $jweProtHdr
    delete_CkStringBuilder $sbJweCompressed
    delete_CkStringBuilder $sbJweUncompressed
    delete_CkJwe $jwe2
    delete_CkStringBuilder $sbOriginalText
    exit
}

# Set the AES wrap key.
CkJwe_SetWrappingKey $jwe2 0 $aesWrappingKey "base64url"

# Decrypt.
CkStringBuilder_Clear $sbOriginalText
set success [CkJwe_DecryptSb $jwe2 0 "utf-8" $sbOriginalText]
if {$success != 1} then {
    puts [CkJwe_lastErrorText $jwe2]
    delete_CkStringBuilder $sbPlainText
    delete_CkJwe $jwe
    delete_CkJsonObject $jweProtHdr
    delete_CkStringBuilder $sbJweCompressed
    delete_CkStringBuilder $sbJweUncompressed
    delete_CkJwe $jwe2
    delete_CkStringBuilder $sbOriginalText
    exit
}

puts "original text from uncompressed JWE: "
puts [CkStringBuilder_getAsString $sbOriginalText]

# ------------------------------------------------
# The output of this example is:
# (Note: Your output data will be different because the content encryption key is randomly generated.)

# eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiemlwIjoiREVGIn0.xuW-pEAIdEUFnk10m8ocursvktO8Of9ByCCAt6LgKkkOtCWCUn1kQw.zpGj-9WVni3cQxyOuZbcGA.0hzP1myua3oYpUHwCIY_3edBUREbUpLaX6wYuJduOdI.Ppc6aEO3y3B8BJ1FKMPjlA
# size of compressed JWE: 212
# eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.N4KeyC7nnSFkieJOyE24_zKeuV_m7v5UKoJb1TgV4Yc_r2RzUPNvyA.6AEdyXSCKx-iMmUJyypSLg.QpixfyrwhGpmwUDp623viik4smPav7vwPLiC2r-V-jwnSfEH3mxWu6DbrIz3mixaqATwynmEBzVPxvS9jTXpSAGCnniib4_0WoPl3r_wF5tlsKOEe--jpNso-DKd1Tp8jJxj3JkFWt3IRnUUKGj17g.sBfDwFc5fzpaI-UW8-SW4g
# size of uncompressed JWE: 303
# original text from compressed JWE: 
# Live long and prosper.
# Live long and prosper.
# Live long and prosper.
# Live long and prosper.
# 
# original text from uncompressed JWE: 
# Live long and prosper.
# Live long and prosper.
# Live long and prosper.
# Live long and prosper.
# 

delete_CkStringBuilder $sbPlainText
delete_CkJwe $jwe
delete_CkJsonObject $jweProtHdr
delete_CkStringBuilder $sbJweCompressed
delete_CkStringBuilder $sbJweUncompressed
delete_CkJwe $jwe2
delete_CkStringBuilder $sbOriginalText