(CkPython) Compress and Encrypt a Large File (Low and Constant Memory Footprint)

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Demonstrates how to compress and encrypt a large file such that the memory footprint remains low and constant.

Note: This example requires Chilkat v9.5.0.99 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 example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

compress = chilkat.CkCompression()
compress.put_Algorithm("deflate")

# Set encryption params.
# The possible values are the same as for the corresponding properties in the Chilkat Crypt2 class/object.
# The encoded IV and Key must be specified as hex.
json = chilkat.CkJsonObject()
json.UpdateString("cryptAlgorithm","aes")
json.UpdateString("cipherMode","cbc")
json.UpdateInt("keyLength",128)
json.UpdateInt("paddingScheme",0)
json.UpdateString("encodedIV","000102030405060708090A0B0C0D0E0F")
json.UpdateString("encodedKey","000102030405060708090A0B0C0D0E0F")

# Do file-to-file compression+encryption in a single call.
inPath = "qa_data/largeFile.dat"
outPath = "c:/temp/qa_output/compressed_encrypted.dat"
success = compress.CompressEncryptFile(json,inPath,outPath)
if (success == False):
    print(compress.lastErrorText())
    sys.exit()

# We can do file-to-file decrypt/decompress like this:
inPath2 = outPath
outPath2 = "c:/temp/qa_output/restored.dat"
success = compress.DecryptDecompressFile(json,inPath2,outPath2)
if (success == False):
    print(compress.lastErrorText())
    sys.exit()

# Note: The above decrypt + decompress is the equivalent of doing the same in these two steps:
crypt = chilkat.CkCrypt2()
crypt.put_CryptAlgorithm("aes")
crypt.put_CipherMode("cbc")
crypt.put_KeyLength(128)
crypt.put_PaddingScheme(0)
crypt.SetEncodedIV("000102030405060708090A0B0C0D0E0F","hex")
crypt.SetEncodedKey("000102030405060708090A0B0C0D0E0F","hex")

decryptedPath = "c:/temp/qa_output/decrypted.dat"
success = crypt.CkDecryptFile(inPath2,decryptedPath)
if (success == False):
    print(crypt.lastErrorText())
    sys.exit()

outPath3 = "c:/temp/qa_output/restored_in_two_steps.dat"
success = compress.DecompressFile(decryptedPath,outPath3)
if (success == False):
    print(compress.lastErrorText())
    sys.exit()

print("Success.")