Lianja

Duplicate SQL Server ENCRYPTBYPASSPHRASE

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Demonstrates how to duplicate SQL Server's ENCRYPTBYPASSPHRASE. Lianja

// 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.

lcPassword = "tEst1234"
lcEncryptedHex_v1 = "0x010000001E8E7DCDBD4061B951999E25D18445D2305474D2D71EEE98A241C755246F58AB"

// Here's an encrypted string using AES256/SHA256
lcEncryptedHex_v2 = "0x02000000FFE880C0354780481E64EF25B6197A02E2A854A4BA9D8D9BDDFDAB27EB56537ABDA0B1D9C4D1050C91B313550DECF429"

loSbEncHex = createobject("CkStringBuilder")
loSbEncHex.Append(lcEncryptedHex_v1)

// If present, we don't want the leading "0x"
if (loSbEncHex.StartsWith("0x",.F.) = .T.) then
    loSbEncHex.RemoveCharsAt(0,2)
endif

loCrypt = createobject("CkCrypt2")
loCrypt.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.
llV1 = loSbEncHex.StartsWith("01",.F.)

lnIvLen = 0

if (llV1 = .T.) then
    loCrypt.CryptAlgorithm = "3des"
    loCrypt.CipherMode = "cbc"
    loCrypt.KeyLength = 168
    lnIvLen = 8
    lcHashAlg = "sha1"
else
    loCrypt.CryptAlgorithm = "aes"
    loCrypt.CipherMode = "cbc"
    loCrypt.KeyLength = 256
    lnIvLen = 16
    lcHashAlg = "sha256"
endif

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

// Get the IV part of the sbEncHex, and also remove it from the StringBuilder.
lcIvHex = loSbEncHex.GetRange(0,lnIvLen * 2,.T.)
? "IV = " + lcIvHex
loCrypt.SetEncodedIV(lcIvHex,"hex")

loSbPassword = createobject("CkStringBuilder")
loSbPassword.Append(lcPassword)
lcPwd_hash = loSbPassword.GetHash(lcHashAlg,"hex","utf-16")
loSbKey = createobject("CkStringBuilder")
loSbKey.Append(lcPwd_hash)
if (llV1 = .T.) 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)
    loSbKey.Shorten(8)
endif

? "crypt key: " + loSbKey.GetAsString()

loCrypt.SetEncodedKey(loSbKey.GetAsString(),"hex")

// Decrypt
loBd = createobject("CkBinData")
loBd.AppendEncoded(loSbEncHex.GetAsString(),"hex")
loCrypt.DecryptBd(loBd)

// 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...
loBd.RemoveChunk(0,8)
lcPlainText = loBd.GetString("utf-8")
? "decrypted plain text: " + lcPlainText

// 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

loEncryptor = createobject("CkCrypt2")
loEncryptor.EncodingMode = "hex"

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

// Generate a random 8-byte IV
loPrng = createobject("CkPrng")
lcIvHex = loPrng.GenRandom(8,"hex")
loEncryptor.SetEncodedIV(lcIvHex,"hex")

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

lnPlainTextLen = 8
lcPlainText = "ABCD1234"

// Encrypt the header + the plain-text.
loBdData = createobject("CkBinData")
loBdData.AppendEncoded("0DF0ADBA","hex")
loBdData.AppendEncoded("0000","hex")
loBdData.AppendInt2(lnPlainTextLen,.T.)
? "header: " + loBdData.GetEncoded("hex")
loBdData.AppendString(lcPlainText,"utf-8")
loEncryptor.EncryptBd(loBdData)

// Compose the result..
loSbEnc = createobject("CkStringBuilder")
loSbEnc.Append("0x01000000")
loSbEnc.Append(lcIvHex)
loSbEnc.Append(loBdData.GetEncoded("hex"))

? "result: " + loSbEnc.GetAsString()


release loSbEncHex
release loCrypt
release loSbPassword
release loSbKey
release loBd
release loEncryptor
release loPrng
release loBdData
release loSbEnc