项目
11/18/2011

Rfc2898DeriveBytes Constructor (String, array<Byte[])

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Initializes a new instance of the Rfc2898DeriveBytes class using a password and salt to derive the key.

Namespace: System.Security.Cryptography
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public Sub New ( _
    password As String, _
    salt As Byte() _
)

public Rfc2898DeriveBytes(
    string password,
    byte[] salt
)

Parameters

password
Type: System.String
The password used to derive the key.

salt
Type: array<System.Byte[]
The key salt used to derive the key.

Exceptions

Exception	Condition
ArgumentException	The specified salt size is smaller than 8 bytes or the iteration count is less than 1.
ArgumentNullException	The password or salt is nulla null reference (Nothing in Visual Basic).

Remarks

The salt size must be 8 bytes or larger.

RFC 2898 includes methods for creating a key and initialization vector (IV) from a password and salt. You can use PBKDF2, a password-based key derivation function, to derive keys using a pseudo-random function that allows keys of virtually unlimited length to be generated. The Rfc2898DeriveBytes class can be used to produce a derived key from a base key and other parameters. In a password-based key derivation function, the base key is a password and the other parameters are a salt value and an iteration count.

For more information about PBKDF2, see RFC 2898, "PKCS #5: Password-Based Cryptography Specification Version 2.0," available on the Request for Comment Web site. See section 5.2, "PBKDF2," for complete details.

Security Note:
Never hard-code a password within your source code. Hard-coded passwords can be retrieved from an assembly by using the Microsoft Intermediate Language Disassembler (Ildasm.exe), by using a hexadecimal editor, or by simply opening up the assembly in a text editor such as Notepad.exe.

Examples

The following example demonstrates how to use the Rfc2898DeriveBytes constructor to encrypt an isolated storage file. This code example is part of a larger example provided for the AesManaged class.

AesManaged#3

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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