求一个加密,解密函数

[liushiying]

求一个加密,解密函数

[programmeraaron]

密文=system.web.security.formsauthentication.encrypt("password","md5")
解密不知道

[xixigongzhu]

具体些：是什么算法？数据是字符串还是字节流？

[Surpass]

关注

[falcon99]

up

[liushiying]

是字节流

[xixigongzhu]

加密：
static byte[] Encrypt(byte[] data, byte[] key) {
DESCryptoServiceProvider desc = new DESCryptoServiceProvider();//des进行加密
MemoryStream ms = new MemoryStream();//存储加密后的数据
CryptoStream cs = new CryptoStream(ms,desc.CreateEncryptor(key, key),CryptoStreamMode.Write);
cs.Write(data, 0, data.Length);//进行加密
cs.FlushFinalBlock();
return ms.ToArray();//取加密后的数据
}

解密：
static byte[] Decrypt(byte[] data, byte[] key) {
DESCryptoServiceProvider desc = new DESCryptoServiceProvider();
MemoryStream ms = new MemoryStream();//存储解密后的数据
CryptoStream cs = new CryptoStream(ms,desc.CreateDecryptor(key, key),CryptoStreamMode.Write);
cs.Write(data, 0, data.Length);//解密数据
cs.FlushFinalBlock();
return ms.ToArray();
}

注意几个问题：
DES加密算法是对称加密，它的Key是8个字节，即64位，加密和解密的Key必须一样。

[Montaque]

呵呵，那是不可逆的。

MD5 是哈希运算

[eileendl]

看看我的加密解密函数：
Imports System.Text
Imports System.Security.Cryptography
Imports System.IO
Public Class Encypt
'--加密函数--
'strEncrKey必须是8位或以上
Shared Function Encrypt(ByVal data As String, ByVal strEncrKey As String) As String
Try
Dim bytes() As Byte = Encoding.Unicode.GetBytes(Data)
Dim byKey() As Byte = System.Text.Encoding.UTF8.GetBytes(strEncrKey.Substring(0, 8))
Dim iv() As Byte = {1, 2, 3, 4, 5, 6, 7, 8}
Dim des As New DESCryptoServiceProvider()
Dim inputByteArray() As Byte = Encoding.UTF8.GetBytes(Data)
Dim ms As New MemoryStream()
Dim cs As New CryptoStream(ms, des.CreateEncryptor(byKey, iv), CryptoStreamMode.Write)
cs.Write(inputByteArray, 0, inputByteArray.Length)
cs.FlushFinalBlock()
Return Convert.ToBase64String(ms.ToArray())
Catch
MsgBox(Err.Description)
Return ""
End Try
End Function

'--解密函数--
'strEncrKey必须是8位或以上
Shared Function Decrypt(ByVal data As String, ByVal strEncrKey As String) As String
Try
Dim bytes() As Byte = Encoding.Unicode.GetBytes(data)
Dim byKey() As Byte = System.Text.Encoding.UTF8.GetBytes(strEncrKey.Substring(0, 8))
Dim iv() As Byte = {1, 2, 3, 4, 5, 6, 7, 8}
Dim des As New DESCryptoServiceProvider()
Dim inputByteArray() As Byte = Encoding.UTF8.GetBytes(data)
Dim ms As New MemoryStream()
inputByteArray = Convert.FromBase64String(data)
Dim cs As New CryptoStream(ms, des.CreateDecryptor(byKey, iv), CryptoStreamMode.Write)
cs.Write(inputByteArray, 0, inputByteArray.Length)
cs.FlushFinalBlock()
Return System.Text.Encoding.UTF8.GetString(ms.ToArray())
Catch
MsgBox(Err.Description)
Return ""
End Try
End Function
End Class

加密解密的Key一定要一样。
调用：
加密：
Dim out As String
out = Encypt.Encrypt(orgString,"ENCR_KEY")

解密：
dim InStr as String
InStr = Encypt.Decrypt(out,"ENCR_KEY"))

[xixigongzhu]

忘了是VB了：
Shared Function Encrypt(data() As Byte, key() As Byte) As Byte()
Dim desc As DESCryptoServiceProvider = new DESCryptoServiceProvider()
Dim ms As MemoryStream = new MemoryStream()
Dim cs As CryptoStream = new CryptoStream(ms, desc.CreateEncryptor(key, key), CryptoStreamMode.Write)
cs.Write(data, 0, data.Length)
cs.FlushFinalBlock()
Return ms.ToArray()
End Function

Shared Function Decrypt(data() As Byte, key() As Byte) As Byte()
Dim desc As DESCryptoServiceProvider = new DESCryptoServiceProvider()
Dim ms As MemoryStream = new MemoryStream()
Dim cs As CryptoStream = new CryptoStream(ms,desc.CreateDecryptor(key, key),CryptoStreamMode.Write)
cs.Write(data, 0, data.Length)
cs.FlushFinalBlock()
Return ms.ToArray()
End Function

[seaneal]

up

[xixigongzhu]

每个加密算法加密之后的字节数是一定的，所以只需要将加密前的字节数定为加密后的长度就可以了。比如DES算法，如果Padding值为PaddingMode.Zeros，如果输入的长度8以内，输出便是8，也就是说，DES只要加密前的字节数以8为单元(8,16,24...)，并且Padding的值为Zeros，输入跟输出的字节数就相同。
DESCryptoServiceProvider desc = new DESCryptoServiceProvider();
desc.Padding = PaddingMode.Zeros;
加密和解密都必须这样设置：
static byte[] Encrypt(byte[] data, byte[] key) {
DESCryptoServiceProvider desc = new DESCryptoServiceProvider();
desc.Padding = PaddingMode.Zeros;
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms,desc.CreateEncryptor(key, key),CryptoStreamMode.Write);
cs.Write(data, 0, data.Length);
cs.FlushFinalBlock();
return ms.ToArray();
}

static byte[] Decrypt(byte[] data, byte[] key) {
DESCryptoServiceProvider desc = new DESCryptoServiceProvider();
desc.Padding = PaddingMode.Zeros;
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms,desc.CreateDecryptor(key, key),CryptoStreamMode.Write);
cs.Write(data, 0, data.Length);
cs.FlushFinalBlock();
return ms.ToArray();
}