Getting "is not static" when trying to deploy

I'm attemping to deploy a crypto class that we use on a desktop app to SQL Server. I'll use the encryptstring/decryptstring found in this class as User Defined Functions on SQL Server. When I try to deploy the class I'm getting this error:

Error 1 Method, property or field 'EncryptString' of class 'EncryptingDecryptingOASISPWDS.Crypto' in assembly 'EncryptingDecryptingOASISPWDS' is not static. EncryptingDecryptingOASISPWDS

Here is the code:

Imports System

Imports System.Data

Imports System.Data.SqlClient

Imports System.Data.SqlTypes

Imports Microsoft.SqlServer.Server

Imports System.Security.Cryptography

Imports System.Text 'for UnicodeEncoding

Imports System.IO 'for MemoryStream, FileStream, Stream, Path

Imports System.Threading 'for Thread.Sleep

Partial Public Class Crypto

'Private Const CodeVersion As String = "01.00.00"

'class member variables

Private m_sPassPhrase As String

'class private variables

Private mbytKey() As Byte 'crypto key

Private mbytIV() As Byte 'Initialization Vector

Private mbKeyIsSet As Boolean = False

Private mksKeyNotSetException As String = "Crypto passphrase is not set."

Private mksPassphraseTooSmall As String = "PassPhrase length must be at least {0} characters."

' class constructors

Public Sub New()

'no passphrase is useful for GetHashString/ValidPassword methods

End Sub

Public Sub New(ByVal CryptoPassPhrase As String)

PassPhrase = CryptoPassPhrase

End Sub

' class public properties

'generate and store encryption key & iv from passphrase

Public Property PassPhrase() As String

Get

Return m_sPassPhrase

End Get

Set(ByVal Value As String)

Const iMinLength As Integer = -1 '-1 disables min length

m_sPassPhrase = Value.Trim

'enforce a rule on minimum length if desired here

If (Value.Length > iMinLength) Or (iMinLength = -1) Then

Dim sha2 As New SHA256Managed()

'256 bits = 32 byte key

mbytKey = sha2.ComputeHash(BytesFromString(m_sPassPhrase))

'convert to Base64 for Initialization Vector, take last 16 chars

Dim sKey As String = Convert.ToBase64String(mbytKey)

mbytIV = Encoding.ASCII.GetBytes(sKey.Remove(0, sKey.Length - 16))

mbKeyIsSet = True

sha2 = Nothing

Else

mbKeyIsSet = False

Throw New Exception(String.Format(mksPassphraseTooSmall, (iMinLength + 1).ToString))

End If

End Set

End Property

'decrypt a stream

Public Function DecryptStream(ByVal EncryptedStream As MemoryStream) As MemoryStream

If mbKeyIsSet Then

Try

'create Crypto Service Provider, set key, transform and crypto stream

Dim oCSP As New RijndaelManaged()

oCSP.Key = mbytKey

oCSP.IV = mbytIV

Dim ct As ICryptoTransform = oCSP.CreateDecryptor()

Dim cs As CryptoStream = New CryptoStream(EncryptedStream, ct, CryptoStreamMode.Read)

'get bytes from encrypted stream

Dim byteArray(EncryptedStream.Length - 1) As Byte

Dim iBytesIn As Integer = cs.Read(byteArray, 0, EncryptedStream.Length)

cs.Close()

'create and write the decrypted output stream

Dim plainStream As New MemoryStream()

plainStream.Write(byteArray, 0, iBytesIn)

Return plainStream

Catch ex As Exception

Return Stream.Null

End Try

Else

Throw New Exception(mksKeyNotSetException)

End If

End Function

'decrypt a string - wrapper without Base64 flag (True by default)

Public Function DecryptString(ByVal EncryptedString As String) As String

Return _DecryptString(EncryptedString, True)

End Function

'decrypt a string - wrapper with Base64 flag

Public Function DecryptString(ByVal EncryptedString As String, ByVal Base64 As Boolean) As String

Return _DecryptString(EncryptedString, Base64)

End Function

'encrypt a stream

Public Function EncryptStream(ByVal PlainStream As MemoryStream) As MemoryStream

Try

'open stream for encrypted data

Dim encStream As New MemoryStream()

'create Crypto Service Provider, set key, transform and crypto stream

Dim oCSP As New RijndaelManaged()

oCSP.Key = mbytKey

oCSP.IV = mbytIV

Dim ct As ICryptoTransform = oCSP.CreateEncryptor()

Dim cs As CryptoStream = New CryptoStream(encStream, ct, CryptoStreamMode.Write)

'get input stream into byte array

Dim byteArray() As Byte = PlainStream.ToArray()

'write input bytes to crypto stream and close up

cs.Write(byteArray, 0, PlainStream.Length)

cs.FlushFinalBlock()

cs.Close()

Return encStream

Catch ex As Exception

Return Stream.Null

End Try

End Function

'encrypt a string - wrapper without Base64 flag (True by default)

<Microsoft.SqlServer.Server.SqlFunction()> _

Function EncryptString(ByVal PlainText As String) As String

Return _EncryptString(PlainText, True)

End Function

''encrypt a string - wrapper with Base64 flag

<Microsoft.SqlServer.Server.SqlFunction()> _

Public Function EncryptString2(ByVal PlainText As String, ByVal Base64 As Boolean) As String

Return _EncryptString(PlainText, Base64)

End Function

'calculates the hash of InputValue, returns a string

'- SHA1 hash is always 20 bytes (160 bits)

Public Function GetHashString(ByVal InputValue As String) As String

Try

Dim inputBytes() As Byte = BytesFromString(InputValue)

Dim hashValue() As Byte = New SHA1Managed().ComputeHash(inputBytes)

Return BytesToHexString(hashValue)

Catch ex As Exception

Return String.Empty

End Try

End Function

'returns True if hash of Passphrase matches HashValue

Public Function ValidPassword(ByVal Passphrase As String, ByVal HashValue As String) As Boolean

Return (GetHashString(Passphrase) = HashValue)

End Function

'internal string decryption

Private Function _DecryptString(ByVal EncryptedString As String, ByVal Base64 As Boolean) As String

Try

'put string in byte array depending on Base64 flag

Dim byteArray() As Byte

If Base64 Then

byteArray = Convert.FromBase64String(EncryptedString)

Else

byteArray = BytesFromString(EncryptedString)

End If

'create the streams, decrypt and return a string

Dim msEnc As New MemoryStream(byteArray)

Dim msPlain As MemoryStream = DecryptStream(msEnc)

Return BytesToString(msPlain.GetBuffer)

Catch ex As Exception

Return String.Empty

End Try

End Function

'internal string encryption

Private Function _EncryptString(ByVal PlainText As String, ByVal Base64 As Boolean) As String

Try

'put string in byte array

Dim byteArray() As Byte = BytesFromString(PlainText)

'create streams and encrypt

Dim msPlain As New MemoryStream(byteArray)

Dim msEnc As MemoryStream = EncryptStream(msPlain)

'return string depending on Base64 flag

If Base64 Then

Return Convert.ToBase64String(msEnc.ToArray)

Else

Return BytesToString(msEnc.ToArray)

End If

Catch ex As Exception

Return String.Empty

End Try

End Function

'returns a Unicode byte array from a string

Private Function BytesFromString(ByVal StringValue As String) As Byte()

Return (New UnicodeEncoding()).GetBytes(StringValue)

End Function

'returns a hex string from a byte array

Private Function BytesToHexString(ByVal byteArray() As Byte) As String

Dim sb As New StringBuilder(40)

Dim bValue As Byte

For Each bValue In byteArray

sb.AppendFormat(bValue.ToString("x2").ToUpper)

Next

Return sb.ToString

End Function

'returns a Unicode string from a byte array

Private Function BytesToString(ByVal byteArray() As Byte) As String

Return (New UnicodeEncoding()).GetString(byteArray)

End Function

'Return True when the file is available for writing

'- returns False if output file locked, for example

Private Function CheckWriteAccess(ByVal FileName As String) As Boolean

'2 second delay with 10,200

Dim iCount As Integer = 0 'retry count

Const iLimit As Integer = 10 'retries

Const iDelay As Integer = 200 'msec

While (iCount < iLimit)

Try

Dim fs As FileStream

fs = New FileStream(FileName, FileMode.Append, _

FileAccess.Write, FileShare.None)

fs.Close()

Return True

Catch ex As Exception

Thread.Sleep(iDelay)

Finally

iCount += 1

End Try

End While

Return False

End Function

End Class

All CLR functions / SP used by SQL Server are required to be Static since sql server cannot instantiate a class before using it... it uses only static methods that does not requires any instance.

So you must declare

<Microsoft.SqlServer.Server.SqlFunction()> _

Static Function EncryptString(ByVal PlainText As String) As String

...