double.low ^= 0xe100000000000000 } return } var ghashReductionTable = []uint16{ 0x0000, 0x1c20, 0x3840, 0x2460, 0x7080, 0x6ca0, 0x48c0, 0x54e0, 0xe100, 0xfd20, 0xd940, 0xc560, 0x9180, 0x8da0, 0xa9c0, 0xb5e0, } // ghashMul sets y to y*H, where H is the GCM key, fixed during New. func ghashMul(productTable *[16]gcmFieldElement, y *gcmFieldElement) { var z gcmFieldElement for i := 0; i < 2; i++ { word := y.high if i == 1 { word = y.low } // Multiplication works by multiplying z by 16 and adding in // one...