(Xojo Plugin) AES and CHACHA20 Encrypt/Decrypt Text

Demonstrates the use of the new EncryptSb and DecryptSb methods introduced in Chilkat v9.5.0.67 to encrypt/decrypt the contents of StringBuilder objects.

Note: This example requires Chilkat v9.5.0.67 or greater.

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

Dim success As Boolean

// First build a string to be encrypted
Dim sb As New Chilkat.StringBuilder
Dim i As Int32
i = 1
While i < 10
    success = sb.AppendInt(i)
    success = sb.Append(" the quick brown fox jumped over the lazy dog." + EndOfLine.Windows)
    i = i + 1
Wend

System.DebugLog(sb.GetAsString())

// The string to be encrypted looks like this:

// 1 the quick brown fox jumped over the lazy dog.
// 2 the quick brown fox jumped over the lazy dog.
// 3 the quick brown fox jumped over the lazy dog.
// 4 the quick brown fox jumped over the lazy dog.
// 5 the quick brown fox jumped over the lazy dog.
// 6 the quick brown fox jumped over the lazy dog.
// ...

Dim crypt As New Chilkat.Crypt2

// Specify the encryption to be used.
// First we'll do AES-128 CBC
crypt.CryptAlgorithm = "aes"
crypt.CipherMode = "cbc"
crypt.KeyLength = 128

Dim ivHex As String
ivHex = "000102030405060708090A0B0C0D0E0F"
crypt.SetEncodedIV ivHex,"hex"

Dim keyHex As String
keyHex = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"
crypt.SetEncodedKey keyHex,"hex"

// When EncryptSb is called, the contents of the source (sb)
// remains unmodified.  The encrypted bytes are written into bdEncrypted.
// If bdEncrypted already contained data, it is replaced with the encrypted bytes.
Dim bdEncrypted As New Chilkat.BinData
success = crypt.EncryptSb(sb,bdEncrypted)
If (success <> True) Then
    System.DebugLog(crypt.LastErrorText)
    Return
End If

// Examine the encrypted bytes:
System.DebugLog(bdEncrypted.GetEncoded("base64_mime"))

// Sample encrypted data:

// 0DdNZ22ckMMJBiaKhAu3wUEfh16XW356NIUsDmNs/xwbHe/p1201OmpfzwXwKktkAefu2pckrBgC
// df+1w8lRo+KAy5n5wlAgMGM/UrsVJsp0BmDPk1vaxKrmrGpSXOVCQs1n2+0atIs5YLiOG+Va3+Mi
// EQNb4YK7bNMmvt0++irBxTiGnkx/RncfKwgkbBUpl2x7yV13MW6lapDT6Md0DKAMsTXFJYGeIdEf
// g2uxDDQzI5gUOUHTMrXQ8paD/K76KKB9Jpp/kAM9z8g/d8KUmuphA7KI64d38xsgOmcITlbhlCQ2
// PDkcU6RRzX0FUTUSMgQukhy0jkLZEjHX9poKJD+iJTOkcQUC3OqR9hKhSrvIgJN4lxdR71MheOoQ
// 2wmvRdq+agTWWh333Vmb6J6yDV79aSpnqEDrA8Ks7Xzciol0gve91+JtVJlJKjWwEzWEU8GxF7Q8
// eaWI70lsC5nTLGcbqgKu6gzkzHlHyHaE2FAQA/d5I2dvfsAYUQCza0Zdyw8mmTtHhlP2Tfxj1uPv
// H4Q7BGuKnx3SWT2CnpbX4091w7KzLAztrbFBo/Tf9w8ZpgTK9k1ryfW9/xnk6rW6iQ==

// Decrypt to restore back to the original:
Dim sbOriginal As New Chilkat.StringBuilder
success = crypt.DecryptSb(bdEncrypted,sbOriginal)
If (success <> True) Then
    System.DebugLog(crypt.LastErrorText)
    Return
End If

// Examine the original data:
System.DebugLog(sbOriginal.GetAsString())

// ----------------------------------------------------------------------------------
// To do chacha20 encryption, just change the settings:

crypt.CryptAlgorithm = "chacha20"
crypt.KeyLength = 256
// The initial count is the initial block counter for the chacha20 algorithm.
// It can be any integer, but must be set to the same when decrypting.
crypt.InitialCount = 22

// EncryptSb completely replaces the contents of bdEncrypted.
success = crypt.EncryptSb(sb,bdEncrypted)

// However.. DecryptSb appends the decrypted text to whatever may
// have already existed within sbOriginal.
success = crypt.DecryptSb(bdEncrypted,sbOriginal)

System.DebugLog("----")
System.DebugLog("The original data should be here twice.  Once from the AES decrypt, and again from the chacha20 decrypt.")
System.DebugLog(sbOriginal.GetAsString())
System.DebugLog("Success.")