HKDF.Expand Method

Namespace: Rebex.Security.Cryptography

Assembly: Rebex.Security.dll (version 7.0.9083)

Expand(HashingAlgorithmId, Byte[], Int32, Byte[])

HKDF Expand function according to section 2.3 of RFC 5869.

Declaration

public static byte[] Expand(HashingAlgorithmId hashingAlgorithmId, byte[] prk, int outputLength, byte[] info = null)

Parameters

Type	Name	Description
HashingAlgorithmId	hashingAlgorithmId	The hash algorithm for HMAC operations.
Byte[]	prk	A byte array that contains the pseudorandom key (the 'PRK' argument from RFC 5869). Its length must be equal to or greater than the hash size of hashingAlgorithmId. This key is usually computed using the Extract(HashingAlgorithmId, Byte[], Byte[]) method.
Int32	outputLength	The length (in bytes) of the output keying material. This is the 'L' argument from RFC 5869. The value must be between 1 and '255 * hash size of hashingAlgorithmId in bytes'.
Byte[]	info	A byte array that contains the context and application-specific information. Can be null. This is the 'info' argument from RFC 5869.

Returns

Type	Description
Byte[]	A byte array that contains the output keying material (the 'OKM' output from RFC 5869).

Exceptions

Type	Condition
ArgumentNullException	The prk is null.
ArgumentException	The prk has an invalid length, or the outputLength is invalid, or the hashingAlgorithmId is not supported.

See Also

Extract(HashingAlgorithmId, Byte[], Byte[])

Expand(HashingAlgorithmId, ArraySegment<Byte>, ArraySegment<Byte>, ArraySegment<Byte>)

HKDF Expand function according to section 2.3 of RFC 5869.

Declaration

public static void Expand(HashingAlgorithmId hashingAlgorithmId, ArraySegment<byte> prk, ArraySegment<byte> output, ArraySegment<byte> info)

Parameters

Type	Name	Description
HashingAlgorithmId	hashingAlgorithmId	The hash algorithm for HMAC operations.
ArraySegment<Byte>	prk	An ArraySegment<T> that contains the pseudorandom key (the 'PRK' argument from RFC 5869). Its length must be equal to or greater than the hash size of hashingAlgorithmId. This key is usually computed using the Extract(HashingAlgorithmId, ArraySegment<Byte>, ArraySegment<Byte>, ArraySegment<Byte>) method.
ArraySegment<Byte>	output	An ArraySegment<T> that will receive the output keying material (the 'OKM' output from RFC 5869). The length of the output (the 'L' argument from RFC 5869) must be between 1 and '255 * hash size of hashingAlgorithmId in bytes'.
ArraySegment<Byte>	info	An ArraySegment<T> that contains the context and application-specific information. Can be empty ArraySegment<T>. This is the 'info' argument from RFC 5869.

Exceptions

Type	Condition
ArgumentException	The prk has an invalid length, or the output has an invalid length, or the hashingAlgorithmId is not supported.

See Also

Extract(HashingAlgorithmId, Byte[], Byte[])