(Chilkat2-Python) Streaming Encryption by Encrypting in Chunks

Encrypt data in chunks.

Chilkat2 Python Downloads install with pip pip3 install chilkat2 or download... Python Module for Windows, Linux, Alpine Linux, MacOS

import chilkat2

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

crypt = chilkat2.Crypt2()

crypt.CryptAlgorithm = "aes"
crypt.CipherMode = "cbc"
crypt.KeyLength = 128

crypt.SetEncodedKey("000102030405060708090A0B0C0D0E0F","hex")
crypt.SetEncodedIV("000102030405060708090A0B0C0D0E0F","hex")

crypt.EncodingMode = "hex"
txt1 = "The quick brown fox jumped over the lazy dog.\r\n"
txt2 = "-\r\n"
txt3 = "Done.\r\n"

sbEncrypted = chilkat2.StringBuilder()

# Encrypt the 1st chunk:
# (don't worry about feeding the data to the encryptor in 
# exact multiples of the encryption algorithm's block size.
# Chilkat will buffer the data.)
crypt.FirstChunk = True
crypt.LastChunk = False
sbEncrypted.Append(crypt.EncryptStringENC(txt1))

# Encrypt the 2nd chunk
crypt.FirstChunk = False
crypt.LastChunk = False
sbEncrypted.Append(crypt.EncryptStringENC(txt2))

# Now encrypt N more chunks...
# Remember -- we're doing this in CBC mode, so each call
# to the encrypt method depends on the state from previous
# calls...
crypt.FirstChunk = False
crypt.LastChunk = False

for i in range(0,5):
    sbEncrypted.Append(crypt.EncryptStringENC(txt1))
    sbEncrypted.Append(crypt.EncryptStringENC(txt2))

# Now encrypt the last chunk:
crypt.FirstChunk = False
crypt.LastChunk = True
sbEncrypted.Append(crypt.EncryptStringENC(txt3))

print(sbEncrypted.GetAsString())

# Now decrypt in one call.
# (The data we're decrypting is both the first AND last chunk.)  
crypt.FirstChunk = True
crypt.LastChunk = True
decryptedText = crypt.DecryptStringENC(sbEncrypted.GetAsString())

print(decryptedText)

# Note: You may decrypt in N chunks by setting the FirstChunk
# and LastChunk properties prior to calling the Decrypt* methods