Chilkat2-Python

Duplicate SQL Server ENCRYPTBYPASSPHRASE

See more Encryption Examples

Demonstrates how to duplicate SQL Server's ENCRYPTBYPASSPHRASE. Chilkat2-Python

import chilkat2

# 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.

password = "tEst1234"
encryptedHex_v1 = "0x010000001E8E7DCDBD4061B951999E25D18445D2305474D2D71EEE98A241C755246F58AB"

# Here's an encrypted string using AES256/SHA256
encryptedHex_v2 = "0x02000000FFE880C0354780481E64EF25B6197A02E2A854A4BA9D8D9BDDFDAB27EB56537ABDA0B1D9C4D1050C91B313550DECF429"

sbEncHex = chilkat2.StringBuilder()
sbEncHex.Append(encryptedHex_v1)

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

crypt = chilkat2.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.
v1 = sbEncHex.StartsWith("01",False)

ivLen = 0

if (v1 == True):
    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"

# 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.
ivHex = sbEncHex.GetRange(0,ivLen * 2,True)
print("IV = " + ivHex)
crypt.SetEncodedIV(ivHex,"hex")

sbPassword = chilkat2.StringBuilder()
sbPassword.Append(password)
pwd_hash = sbPassword.GetHash(hashAlg,"hex","utf-16")
sbKey = chilkat2.StringBuilder()
sbKey.Append(pwd_hash)
if (v1 == True):
    # 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)

print("crypt key: " + sbKey.GetAsString())

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

# Decrypt
bd = chilkat2.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)
plainText = bd.GetString("utf-8")
print("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

encryptor = chilkat2.Crypt2()
encryptor.EncodingMode = "hex"

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

# Generate a random 8-byte IV
prng = chilkat2.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")

plainTextLen = 8
plainText = "ABCD1234"

# Encrypt the header + the plain-text.
bdData = chilkat2.BinData()
bdData.AppendEncoded("0DF0ADBA","hex")
bdData.AppendEncoded("0000","hex")
bdData.AppendInt2(plainTextLen,True)
print("header: " + bdData.GetEncoded("hex"))
bdData.AppendString(plainText,"utf-8")
encryptor.EncryptBd(bdData)

# Compose the result..
sbEnc = chilkat2.StringBuilder()
sbEnc.Append("0x01000000")
sbEnc.Append(ivHex)
sbEnc.Append(bdData.GetEncoded("hex"))

print("result: " + sbEnc.GetAsString())