Hpke.LabeledExpand Method

Compute the output of the LabeledExpand function as defined in RFC9180.

Syntax

public static byte[] LabeledExpand(
	int numBytes,
	byte[] prk,
	string label,
	byte[] info,
	Hpke.CurveName curveName,
	Hpke.AeadAlg aeadAlg
)

Public Shared Function LabeledExpand ( _
	numBytes As Integer, _
	prk As Byte(), _
	label As String, _
	info As Byte(), _
	curveName As Hpke.CurveName, _
	aeadAlg As Hpke.AeadAlg _
) As Byte()

Parameters

numBytes

Required number of bytes (L) of output keying material.

prk

Pseudorandom key (prk)

label

Label string

info

Byte string info

curveName

Type: Hpke.CurveName
ECDH curve used in scheme

aeadAlg

Type: Hpke.AeadAlg
AEAD encryption algorithm used in the scheme or 0 (default) to indicate KDF is being used inside a KEM algorithm.

Return Value

Remarks

Example

int Nk = 16;
// key = LabeledExpand(secret, 'key', key_schedule_context, Nk)
byte[] key = Hpke.LabeledExpand(Nk, Cnv.FromHex("12fff91991e93b48de37e7daddb52981084bd8aa64289c3788471d9a9712f397"), "key",
   Cnv.FromHex("00725611c9d98c07c03f60095cd32d400d8347d45ed67097bbad50fc56da742d07cb6cffde367bb0565ba28bb02c90744a20f5ef37f30523526106f637abb05449"),
   Hpke.CurveName.X25519, Hpke.AeadAlg.Aes_128_Gcm);
// 4531685d41d65f03dc48f6b8302c05b0

See Also

VB6/C equivalent: HPKE_LabeledExpand

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