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(Excel) AES and CHACHA20 Encrypt/Decrypt TextDemonstrates 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.
' This example assumes the Chilkat API to have been previously unlocked. ' See Global Unlock Sample for sample code. ' First build a string to be encrypted Dim sb As Chilkat.StringBuilder Set sb = Chilkat.NewStringBuilder i = 1 Do While i < 10 success = sb.AppendInt(i) success = sb.Append(" the quick brown fox jumped over the lazy dog." & vbCrLf) i = i + 1 Loop Debug.Print 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 Chilkat.Crypt2 Set crypt = Chilkat.NewCrypt2 ' Specify the encryption to be used. ' First we'll do AES-128 CBC crypt.CryptAlgorithm = "aes" crypt.CipherMode = "cbc" crypt.KeyLength = 128 ivHex = "000102030405060708090A0B0C0D0E0F" crypt.SetEncodedIV ivHex,"hex" 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 Chilkat.BinData Set bdEncrypted = Chilkat.NewBinData success = crypt.EncryptSb(sb,bdEncrypted) If (success <> True) Then Debug.Print crypt.LastErrorText Exit Sub End If ' Examine the encrypted bytes: Debug.Print 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 Chilkat.StringBuilder Set sbOriginal = Chilkat.NewStringBuilder success = crypt.DecryptSb(bdEncrypted,sbOriginal) If (success <> True) Then Debug.Print crypt.LastErrorText Exit Sub End If ' Examine the original data: Debug.Print 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) Debug.Print "----" Debug.Print "The original data should be here twice. Once from the AES decrypt, and again from the chacha20 decrypt." Debug.Print sbOriginal.GetAsString() Debug.Print "Success." |
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