VB.NET

Duplicate SQL Server ENCRYPTBYPASSPHRASE

See more Encryption Examples

Demonstrates how to duplicate SQL Server's ENCRYPTBYPASSPHRASE. VB.NET

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

' For SQL Server 2008 - SQL Server 2016 we must use TripleDES with SHA1
' For SQL Server 2017 and later, use AES256 / SHA256.

Dim password As String = "tEst1234"
Dim encryptedHex_v1 As String = "0x010000001E8E7DCDBD4061B951999E25D18445D2305474D2D71EEE98A241C755246F58AB"


' Here's an encrypted string using AES256/SHA256
Dim encryptedHex_v2 As String = "0x02000000FFE880C0354780481E64EF25B6197A02E2A854A4BA9D8D9BDDFDAB27EB56537ABDA0B1D9C4D1050C91B313550DECF429"

Dim sbEncHex As New Chilkat.StringBuilder
sbEncHex.Append(encryptedHex_v1)

' If present, we don't want the leading "0x"
If (sbEncHex.StartsWith("0x",False) = True) Then
    sbEncHex.RemoveCharsAt(0,2)
End If


Dim crypt As New Chilkat.Crypt2
crypt.EncodingMode = "hex"

' The encrypted hex string will begin with either 01000000 or 02000000
' version 1 is produced by SQL Server 2008 to SQL Server 2016, and we must use TripleDES with SHA1
' version 2 is for SQL Server 2017 and later, and uses AES256 / SHA256.
Dim v1 As Boolean = sbEncHex.StartsWith("01",False)

Dim ivLen As Integer = 0
Dim hashAlg As String

If (v1 = True) Then
    crypt.CryptAlgorithm = "3des"
    crypt.CipherMode = "cbc"
    crypt.KeyLength = 168
    ivLen = 8
    hashAlg = "sha1"
Else
    crypt.CryptAlgorithm = "aes"
    crypt.CipherMode = "cbc"
    crypt.KeyLength = 256
    ivLen = 16
    hashAlg = "sha256"
End If


' Remove the SQL Server version info (i.e. the "01000000")
sbEncHex.RemoveCharsAt(0,8)

' Get the IV part of the sbEncHex, and also remove it from the StringBuilder.
Dim ivHex As String = sbEncHex.GetRange(0,ivLen * 2,True)
Debug.WriteLine("IV = " & ivHex)
crypt.SetEncodedIV(ivHex,"hex")

Dim sbPassword As New Chilkat.StringBuilder
sbPassword.Append(password)
Dim pwd_hash As String = sbPassword.GetHash(hashAlg,"hex","utf-16")
Dim sbKey As New Chilkat.StringBuilder
sbKey.Append(pwd_hash)
If (v1 = True) Then
    ' For v1, we only want the 1st 16 bytes of the 20 byte hash.
    ' (remember, the hex encoding uses 2 chars per byte, so we remove the last 8 chars)
    sbKey.Shorten(8)
End If


Debug.WriteLine("crypt key: " & sbKey.GetAsString())

crypt.SetEncodedKey(sbKey.GetAsString(),"hex")


' Decrypt
Dim bd As New Chilkat.BinData
bd.AppendEncoded(sbEncHex.GetAsString(),"hex")
crypt.DecryptBd(bd)

' The result is composed of a header of 8 bytes which we can discard.
' The remainder is the decrypted text.

' The header we are discarding is composed of:
' Bytes 0-3: Magic number equal to 0DF0ADBA
' Bytes 4-5: Number of integrity bytes, which is 0 unless an authenticator is used. We're assuming no authenticator is used.
' Bytes 6-7: Number of plain-text bytes. We really don't need this because the CBC padding takes care of it.

' Therefore, just return the data after the 1st 8 bytes.
' Assuming the encrypted string was utf-8 text...
bd.RemoveChunk(0,8)
Dim plainText As String = bd.GetString("utf-8")
Debug.WriteLine("decrypted plain text: " & plainText)

' The output:

' IV = 1E8E7DCDBD4061B9
' crypt key: 710B9C2E61ACCC9570D4112203BD9738
' decrypted plain text: Hello world.


' ------------------------------------------------------------------------------------------
' To encrypt, do the reverse...

' Let's do v1 with TripleDES with SHA1

Dim encryptor As New Chilkat.Crypt2
encryptor.EncodingMode = "hex"

encryptor.CryptAlgorithm = "3des"
encryptor.CipherMode = "cbc"
encryptor.KeyLength = 168

' Generate a random 8-byte IV
Dim prng As New Chilkat.Prng
ivHex = prng.GenRandom(8,"hex")
encryptor.SetEncodedIV(ivHex,"hex")

' The binary password is generated the same as above.
' We'll use the same password (and same binary password)
encryptor.SetEncodedKey(sbKey.GetAsString(),"hex")

Dim plainTextLen As Integer = 8
plainText = "ABCD1234"

' Encrypt the header + the plain-text.
Dim bdData As New Chilkat.BinData
bdData.AppendEncoded("0DF0ADBA","hex")
bdData.AppendEncoded("0000","hex")
bdData.AppendInt2(plainTextLen,True)
Debug.WriteLine("header: " & bdData.GetEncoded("hex"))
bdData.AppendString(plainText,"utf-8")
encryptor.EncryptBd(bdData)

' Compose the result..
Dim sbEnc As New Chilkat.StringBuilder
sbEnc.Append("0x01000000")
sbEnc.Append(ivHex)
sbEnc.Append(bdData.GetEncoded("hex"))

Debug.WriteLine("result: " & sbEnc.GetAsString())