internal: initialize Ristretto constants

internal/edwards25519/const.go

@@ -0,0 +1,36 @@
+package edwards25519
+
+import (
+	"math/big"
+	"sync"
+
+	. "github.com/gtank/ristretto255/internal/edwards25519/internal/edwards25519"
+)
+
+var (
+	CONST_SQRT_M1, _           = new(big.Int).SetString("19681161376707505956807079304988542015446066515923890162744021073123829784752", 10)
+	CONST_SQRT_AD_MINUS_ONE, _ = new(big.Int).SetString("25063068953384623474111414158702152701244531502492656460079210482610430750235", 10)
+	CONST_INVSQRT_A_MINUS_D, _ = new(big.Int).SetString("54469307008909316920995813868745141605393597292927456921205312896311721017578", 10)
+	CONST_ONE_MINUS_D_SQ, _    = new(big.Int).SetString("1159843021668779879193775521855586647937357759715417654439879720876111806838", 10)
+	CONST_D_MINUS_ONE_SQ, _    = new(big.Int).SetString("40440834346308536858101042469323190826248399146238708352240133220865137265952", 10)
+
+	SQRT_M1           FieldElement
+	SQRT_AD_MINUS_ONE FieldElement
+	INVSQRT_A_MINUS_D FieldElement
+	ONE_MINUS_D_SQ    FieldElement
+	D_MINUS_ONE_SQ    FieldElement
+)
+
+var once sync.Once
+
+func init() {
+	once.Do(initConstants)
+}
+
+func initConstants() {
+	feFromBig(&SQRT_M1, CONST_SQRT_M1)
+	feFromBig(&SQRT_AD_MINUS_ONE, CONST_SQRT_AD_MINUS_ONE)
+	feFromBig(&INVSQRT_A_MINUS_D, CONST_INVSQRT_A_MINUS_D)
+	feFromBig(&ONE_MINUS_D_SQ, CONST_ONE_MINUS_D_SQ)
+	feFromBig(&D_MINUS_ONE_SQ, CONST_D_MINUS_ONE_SQ)
+}