What's the best way to encrypt short strings i

问题:

My boss wants me to encrypt some information used during data transfer. The individual strings to be encrypted are between eight and twenty characters long. A single password must be used to encrypt and decrypt so I need a symmetric alogrithm. I don't want to roll my own - I want to use one built into .NET from C#.

So, which algorithm is best?

回答1:

TripleDes ?

You can use the System.Security.Cryptography.TripleDESCryptoServiceProvider

Small amount of code to encrypy/decrypt... does exactly what it says on the tin :)

回答2:

TripleDES is a very good option, but you can also consider AesCryptoServiceProvider (AES), which is a modern symmetric cipher.

回答3:

Here is encrypt & decrypt function with des3 encryption

''' <summary>
''' Encrypts a memory string (i.e. variable).
''' </summary>
''' <param name="data">String to be encrypted.</param>
''' <param name="key">Encryption key.</param>
''' <param name="iv">Encryption initialization vector.</param>
''' <returns>Encrypted string.</returns>
Public Shared Function Encrypt(ByVal data As String, ByVal key As String, ByVal iv As String) As String
    Dim bdata As Byte() = Encoding.ASCII.GetBytes(data)
    Dim bkey As Byte() = HexToBytes(key)
    Dim biv As Byte() = HexToBytes(iv)

    Dim stream As MemoryStream = New MemoryStream
    Dim encStream As CryptoStream = New CryptoStream(stream, des3.CreateEncryptor(bkey, biv), CryptoStreamMode.Write)

    encStream.Write(bdata, 0, bdata.Length)
    encStream.FlushFinalBlock()
    encStream.Close()

    Return BytesToHex(stream.ToArray())
End Function

''' <summary>
''' Decrypts a memory string (i.e. variable).
''' </summary>
''' <param name="data">String to be decrypted.</param>
''' <param name="key">Original encryption key.</param>
''' <param name="iv">Original initialization vector.</param>
''' <returns>Decrypted string.</returns>
Public Shared Function Decrypt(ByVal data As String, ByVal key As String, ByVal iv As String) As String
    Dim bdata As Byte() = HexToBytes(data)
    Dim bkey As Byte() = HexToBytes(key)
    Dim biv As Byte() = HexToBytes(iv)

    Dim stream As MemoryStream = New MemoryStream
    Dim encStream As CryptoStream = New CryptoStream(stream, des3.CreateDecryptor(bkey, biv), CryptoStreamMode.Write)

    encStream.Write(bdata, 0, bdata.Length)
    encStream.FlushFinalBlock()
    encStream.Close()

    Return Encoding.ASCII.GetString(stream.ToArray())
End Function

回答4:

.net security classes:

Hash

* MD5
* MD5Cng
* SHA1
* SHA1Managed
* SHA1Cng
* SHA256
* SHA256Managed
* SHA256Cng
* SHA384
* SHA384Managed
* SHA384Cng
* SHA512
* SHA512Managed
* SHA512Cng

Symmetric Encryption: Uses the same key for encryption and decryption.

* DES
* DESCryptoServiceProvider
* TripleDES
* TripleDESCryptoServiceProvider
* Aes
* AesCryptoServiceProvider
* AesManaged
* RC2
* RC2CryptoServiceProvider
* Rijandel
* RijandelManaged

Asymmetric Encryption: Uses different keys for encryption and decryption.

* DSA
* DSACryptoServiceProvider
* ECDsa
* ECDsaCng
* ECDiffieHellman
* ECDiffieHellmanCng
* RSA
* RSACryptoServideProvider

回答5:

You could just use RSA encryption, since these are short strings, which will make key exchange simpler.

How much you can encrypt with RSA is based on the key length.

I am a fan of the rsa library from bouncy castle.

回答6:

DES is pretty much obsolete at this point. Here is the Wikipedia. If you are changing the key a lot, it might be adequate, but if you are relying on a key for a while, AES seems like a better choice.

Of course it is a question of how much protection you need. But AES is build right in there too.

I have used AES for small strings, and it works nice.

What I have read about TripleDES is that since DES is easily crackable, TripleDES is still not substantial.