Kdf.Bytes Method

Generate a key-encryption key (KEK) from input keying material (IKM) using a key derivation function (KDF).

Syntax

public static byte[] Bytes(
   int dkLen,
   byte[] ikm,
   Kdf.KdfAlg kdfAlg = Kdf.KdfAlg.X963,
   Kdf.HashAlg hashAlg = Kdf.HashAlg.Sha1,
   byte[] sharedInfo = null,
   string paramString = "" 
)

Public Shared Function Bytes (
   dkLen As Integer,
   ikm As Byte(),
   Optional kdfAlg As Kdf.KdfAlg = Kdf.KdfAlg.X963,
   Optional hashAlg As Kdf.HashAlg = Kdf.HashAlg.Sha1,
   Optional sharedInfo As Byte() = Nothing,
   Optional paramString As String = "" 
) As Byte()

Parameters

dkLen  Int32

Required length of output key material in bytes.

ikm  Byte

Input key material/shared secret.

kdfAlg  Kdf.KdfAlg  (Optional)

Key derivation function to use.

hashAlg  Kdf.HashAlg  (Optional)

Hash algorithm to use with the key derivation function (default is SHA-1)

sharedInfo  Byte  (Optional)

SharedInfo (optional)

paramString  String  (Optional)

Optional parameters. Set as "" for defaults. Pass attribute-value salt=<hex-digits> to set the optional salt parameter for the HKDF algorithm, e.g. "salt=606162636465666768696a6b6c6d6e6f;"

Return Value

Example

// [[RFC5869]] A.1.  Test Case 1 Basic test case with SHA-256
int nbytes = 42;
byte[] zz = "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b".FromHex();
byte [] info = "f0f1f2f3f4f5f6f7f8f9".FromHex();
byte[] kek = Kdf.Bytes(nbytes, zz, Kdf.KdfAlg.Hkdf, Kdf.HashAlg.Sha256, info, "salt=000102030405060708090a0b0c");
Console.WriteLine("KEK={0}", Cnv.ToHex(kek));
// KEK=3CB25F25FAACD57A90434F64D0362F2A2D2D0A90CF1A5A4C5DB02D56ECC4C5BF34007208D5B887185865

See Also

VB6/C equivalent: KDF_Bytes

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