Lianja

Streaming Encryption by Encrypting in Chunks

See more Encryption Examples

Encrypt data in chunks. Lianja

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

loCrypt = createobject("CkCrypt2")

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

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

loCrypt.EncodingMode = "hex"
lcTxt1 = "The quick brown fox jumped over the lazy dog." + Chr(13) + Chr(10)
lcTxt2 = "-" + Chr(13) + Chr(10)
lcTxt3 = "Done." + Chr(13) + Chr(10)

loSbEncrypted = createobject("CkStringBuilder")

// 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.)
loCrypt.FirstChunk = .T.
loCrypt.LastChunk = .F.
loSbEncrypted.Append(loCrypt.EncryptStringENC(lcTxt1))

// Encrypt the 2nd chunk
loCrypt.FirstChunk = .F.
loCrypt.LastChunk = .F.
loSbEncrypted.Append(loCrypt.EncryptStringENC(lcTxt2))

// 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...
loCrypt.FirstChunk = .F.
loCrypt.LastChunk = .F.

for i = 0 to 4
    loSbEncrypted.Append(loCrypt.EncryptStringENC(lcTxt1))
    loSbEncrypted.Append(loCrypt.EncryptStringENC(lcTxt2))
next

// Now encrypt the last chunk:
loCrypt.FirstChunk = .F.
loCrypt.LastChunk = .T.
loSbEncrypted.Append(loCrypt.EncryptStringENC(lcTxt3))

? loSbEncrypted.GetAsString()

// Now decrypt in one call.
// (The data we're decrypting is both the first AND last chunk.)  
loCrypt.FirstChunk = .T.
loCrypt.LastChunk = .T.
lcDecryptedText = loCrypt.DecryptStringENC(loSbEncrypted.GetAsString())

? lcDecryptedText

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


release loCrypt
release loSbEncrypted