KDF_1(K, D) = KDF_GOSTR3411_2012_256(K, "level1", D);

KDF_2(K, D) = KDF_GOSTR3411_2012_256(K, "level2", D); and

KDF_3(K, D) = KDF_GOSTR3411_2012_256(K, "level3", D).