C#/.NET字符串加密和解密实现(AES和RSA代码举例)

public

class

Crypto

{

private

static

byte

[] _salt = Encoding.ASCII.GetBytes(

"o6806642kbM7c5"

);

/// <summary>

/// Encrypt the given string using AES.  The string can be decrypted using

/// DecryptStringAES().  The sharedSecret parameters must match.

/// </summary>

/// <param name="plainText">The text to encrypt.</param>

/// <param name="sharedSecret">A password used to generate a key for encryption.</param>

public

static

string

EncryptStringAES(

string

plainText,

string

sharedSecret)

{

if

(

string

.IsNullOrEmpty(plainText))

throw

new

ArgumentNullException(

"plainText"

);

if

(

string

.IsNullOrEmpty(sharedSecret))

throw

new

ArgumentNullException(

"sharedSecret"

);

string

outStr =

null

;   

// Encrypted string to return

RijndaelManaged aesAlg =

null

;  

// RijndaelManaged object used to encrypt the data.

try

{

// generate the key from the shared secret and the salt

Rfc2898DeriveBytes key =

new

Rfc2898DeriveBytes(sharedSecret, _salt);

// Create a RijndaelManaged object

aesAlg =

new

RijndaelManaged();

aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);

// Create a decryptor to perform the stream transform.

ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

// Create the streams used for encryption.

using

(MemoryStream msEncrypt =

new

MemoryStream())

{

// prepend the IV

msEncrypt.Write(BitConverter.GetBytes(aesAlg.IV.Length),0,

sizeof

(

int

));

msEncrypt.Write(aesAlg.IV, 0, aesAlg.IV.Length);

using

(CryptoStream csEncrypt =

new

CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))

{

using

(StreamWriter swEncrypt =

new

StreamWriter(csEncrypt))

{

//Write all data to the stream.

swEncrypt.Write(plainText);

}

}

outStr =Convert.ToBase64String(msEncrypt.ToArray());

}

}

finally

{

// Clear the RijndaelManaged object.

if

(aesAlg !=

null

)

aesAlg.Clear();

}

// Return the encrypted bytes from the memory stream.

return

outStr;

}

/// <summary>

/// Decrypt the given string.  Assumes the string was encrypted using

/// EncryptStringAES(),using an identical sharedSecret.

/// </summary>

/// <param name="cipherText">The text to decrypt.</param>

/// <param name="sharedSecret">A password used to generate a key for decryption.</param>

public

static

string

DecryptStringAES(

string

cipherText,

string

sharedSecret)

{

if

(

string

.IsNullOrEmpty(cipherText))

throw

new

ArgumentNullException(

"cipherText"

);

if

(

string

.IsNullOrEmpty(sharedSecret))

throw

new

ArgumentNullException(

"sharedSecret"

);

// Declare the RijndaelManaged object

// used to decrypt the data.

RijndaelManaged aesAlg =

null

;

// Declare the string used to hold

// the decrypted text.

string

plaintext =

null

;

try

{

// generate the key from the shared secret and the salt

Rfc2898DeriveBytes key =

new

Rfc2898DeriveBytes(sharedSecret, _salt);

// Create the streams used for decryption.  

byte

[] bytes = Convert.FromBase64String(cipherText);

using

(MemoryStream msDecrypt =

new

MemoryStream(bytes))

{

// Create a RijndaelManaged object

// with the specified key and IV.

aesAlg =

new

RijndaelManaged();

aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);

// Get the initialization vector from the encrypted stream

aesAlg.IV = ReadByteArray(msDecrypt);

// Create a decrytor to perform the stream transform.

ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

using

(CryptoStream csDecrypt =

new

CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))

{

using

(StreamReader srDecrypt =

new

StreamReader(csDecrypt))

// Read the decrypted bytes from the decrypting stream

// and place them in a string.

plaintext =srDecrypt.ReadToEnd();

}

}

}

finally

{

// Clear the RijndaelManaged object.

if

(aesAlg !=

null

)

aesAlg.Clear();

}

return

plaintext;

}

private

static

byte

[] ReadByteArray(Stream s)

{

byte

[] rawLength =

new

byte

[

sizeof

(

int

)];

if

(s.Read(rawLength, 0, rawLength.Length) != rawLength.Length)

{

throw

new

SystemException(

"Stream did not contain properly formatted byte array"

);

}

byte

[] buffer =

new

byte

[BitConverter.ToInt32(rawLength, 0)];

if

(s.Read(buffer, 0, buffer.Length) != buffer.Length)

{

throw

new

SystemException(

"Did not read byte array properly"

);

}

return

buffer;

}

}

var

provider =

new

System.Security.Cryptography.RSACryptoServiceProvider();

provider.ImportParameters(your_rsa_key);

var

encryptedBytes = provider.Encrypt(

System.Text.Encoding.UTF8.GetBytes(

"Hello World!"

),

true

);

string

decryptedTest = System.Text.Encoding.UTF8.GetString(

provider.Decrypt(encryptedBytes,

true

));