Rfc2898DeriveBytes.GetBytes(Int32) Method

Definition

Namespace:

System.Security.Cryptography

Assembly:

System.Security.Cryptography.dll

Source:

Rfc2898DeriveBytes.cs

Returns the pseudo-random key for this object.

public override byte[] GetBytes (int cb);

Parameters

cb

Int32

The number of pseudo-random key bytes to generate.

Returns

Byte[]

A byte array filled with pseudo-random key bytes.

Exceptions

ArgumentOutOfRangeException

cb is out of range. This parameter requires a non-negative number.

Examples

The following example shows how to use the GetBytes method to get the key for an instance of Rfc2898DeriveBytes. This code example is part of a larger example provided for the Rfc2898DeriveBytes class.

            try
            {
                Rfc2898DeriveBytes k1 = new Rfc2898DeriveBytes(pwd1, salt1,
myIterations);
                Rfc2898DeriveBytes k2 = new Rfc2898DeriveBytes(pwd1, salt1);
                // Encrypt the data.
                Aes encAlg = Aes.Create();
                encAlg.Key = k1.GetBytes(16);
                MemoryStream encryptionStream = new MemoryStream();
                CryptoStream encrypt = new CryptoStream(encryptionStream,
encAlg.CreateEncryptor(), CryptoStreamMode.Write);
                byte[] utfD1 = new System.Text.UTF8Encoding(false).GetBytes(
data1);

Remarks

The Rfc2898DeriveBytes class implements PBKDF2 functionality by using a pseudorandom number generator based on HMACSHA1. The Rfc2898DeriveBytes class takes a password, a salt, and an iteration count, and then generates keys through calls to the GetBytes method. Repeated calls to this method will not generate the same key; instead, appending two calls of the GetBytes method with a cb parameter value of 20 is the equivalent of calling the GetBytes method once with a cb parameter value of 40.

Applies to

See also

• Cryptographic Services