如何修复：rfc2898DeriveBytes 和 AES 加密出现“填充无效且无法删除”错误？

Question

I am trying to encrypt and decrypt text by using the rfc2898 Derive bytes method to generate an iv and key to use with AES encryption however I run in to padding is invalid and cannot be removed whenever I try to decrypt a text with the same password. This will be used to encrypt a text and sent to another user and they will use the same password to decrypt the text.

Here is the line of code where the error occurs:

plaintext = srDecrypt.ReadToEnd()

And here is the call stack:

Internal.Cryptography.UniversalCryptoDecryptor.DepadBlock(byte[], int, int)
    Internal.Cryptography.UniversalCryptoDecryptor.UncheckedTransformFinalBlock(byte[], int, int)
    Internal.Cryptography.UniversalCryptoTransform.TransformFinalBlock(byte[], int, int)
    System.Security.Cryptography.CryptoStream.ReadAsyncCore(byte[], int, int, System.Threading.CancellationToken, bool)
    System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
    System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(System.Threading.Tasks.Task)
    System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(System.Threading.Tasks.Task)
    System.Runtime.CompilerServices.TaskAwaiter<TResult>.GetResult()
    System.Security.Cryptography.CryptoStream.Read(byte[], int, int)
    System.IO.StreamReader.ReadBuffer()

*edit Here is the decrypt function

dim salt(8) as byte
  Function Decrypt(ByVal password As String, ByVal ciphertext As String)
        'variable to hold the string
        Dim plaintext As String = ""

        'creates the encrypted byte
        Dim encrypted() As Byte = Convert.FromBase64String(ciphertext)

        'fills the array with random values
        Using rngCsp As New RNGCryptoServiceProvider()
            rngCsp.GetBytes(salt)
        End Using

        'number of iterations to use
        Dim iterations As Integer = 1000

        'turns the password into a key
        Dim crypt As New Rfc2898DeriveBytes(password, salt, iterations)

        Using aesencrypt As Aes = Aes.Create()

            'creates the key and the iv
            aesencrypt.Key = crypt.GetBytes(32)
            aesencrypt.IV = crypt.GetBytes(16)

            ' Create a decryptor to perform the stream transform.
            Dim decryptor As ICryptoTransform = aesencrypt.CreateDecryptor(aesencrypt.Key, aesencrypt.IV)

            ' Create the streams used for decryption.
            Using msDecrypt As New MemoryStream(encrypted)

                Using csDecrypt As New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)

                    Using srDecrypt As New StreamReader(csDecrypt)
                        ' Read the decrypted bytes from the decrypting stream
                        ' and place them in a string.
                        plaintext = srDecrypt.ReadToEnd()
                        srDecrypt.Close()
                    End Using
                End Using
            End Using
        End Using
        Return plaintext
    End Function

The encrypt function is mostly the same but with the encrypt methods instead of the decrypt methods.

Answer 1

Removing the following lines as it causes the program to use different salts:

'fills the array with random values
        Using rngCsp As New RNGCryptoServiceProvider()
            rngCsp.GetBytes(salt)
        End Using

This allows the same salt to be used when encrypting and decrypting.