Rfc2898DeriveBytes Class

July 28, 2014

Implements password-based key derivation functionality, PBKDF2, by using a pseudo-random number generator based on HMACSHA1.

System.Object
  System.Security.Cryptography.DeriveBytes
    System.Security.Cryptography.Rfc2898DeriveBytes

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

public class Rfc2898DeriveBytes : DeriveBytes

The Rfc2898DeriveBytes type exposes the following members.

  NameDescription
Public methodRfc2898DeriveBytes(String, Byte[])Initializes a new instance of the Rfc2898DeriveBytes class using a password and salt to derive the key.
Public methodRfc2898DeriveBytes(Byte[], Byte[], Int32)Initializes a new instance of the Rfc2898DeriveBytes class using a password, a salt, and number of iterations to derive the key.
Public methodRfc2898DeriveBytes(String, Byte[], Int32)Initializes a new instance of the Rfc2898DeriveBytes class using a password, a salt, and number of iterations to derive the key.
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  NameDescription
Public propertyIterationCountGets or sets the number of iterations for the operation.
Public propertySaltGets or sets the key salt value for the operation.
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  NameDescription
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetBytesReturns a pseudo-random key from a password, salt and iteration count. (Overrides DeriveBytes.GetBytes(Int32).)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodResetResets the state of the operation. (Overrides DeriveBytes.Reset().)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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Rfc2898DeriveBytes takes a password, a salt, and an iteration count, and then generates keys through calls to the GetBytes method.

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 Comments Web site. See section 5.2, "PBKDF2," for complete details.

Security noteSecurity 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.

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

AesManaged#3

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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