Added AESCTR_DRBG implementation (beta).

[BearSSL] / src / ec / ec_prime_i31.c

diff --git a/src/ec/ec_prime_i31.c b/src/ec/ec_prime_i31.c
index 440641e..0586a3b 100644 (file)
--- a/src/ec/ec_prime_i31.c
+++ b/src/ec/ec_prime_i31.c
@@ -135,7 +135,7 @@ typedef struct {
 
 /*
  * We use a custom interpreter that uses a dozen registers, and
- * only four operations:
+ * only six operations:
  *    MSET(d, a)       copy a into d
  *    MADD(d, a)       d = d+a (modular)
  *    MSUB(d, a)       d = d-a (modular)
@@ -717,6 +717,14 @@ api_order(int curve, size_t *len)
        return cd->order;
 }
 
+static size_t
+api_xoff(int curve, size_t *len)
+{
+       api_generator(curve, len);
+       *len >>= 1;
+       return 1;
+}
+
 static uint32_t
 api_mul(unsigned char *G, size_t Glen,
        const unsigned char *x, size_t xlen, int curve)
@@ -732,6 +740,19 @@ api_mul(unsigned char *G, size_t Glen,
        return r;
 }
 
+static size_t
+api_mulgen(unsigned char *R,
+       const unsigned char *x, size_t xlen, int curve)
+{
+       const unsigned char *G;
+       size_t Glen;
+
+       G = api_generator(curve, &Glen);
+       memcpy(R, G, Glen);
+       api_mul(R, Glen, x, xlen, curve);
+       return Glen;
+}
+
 static uint32_t
 api_muladd(unsigned char *A, const unsigned char *B, size_t len,
        const unsigned char *x, size_t xlen,
@@ -743,12 +764,17 @@ api_muladd(unsigned char *A, const unsigned char *B, size_t len,
 
        /*
         * TODO: see about merging the two ladders. Right now, we do
-        * two independant point multiplications, which is a bit
+        * two independent point multiplications, which is a bit
         * wasteful of CPU resources (but yields short code).
         */
 
        cc = id_to_curve(curve);
        r = point_decode(&P, A, len, cc);
+       if (B == NULL) {
+               size_t Glen;
+
+               B = api_generator(curve, &Glen);
+       }
        r &= point_decode(&Q, B, len, cc);
        point_mul(&P, x, xlen, cc);
        point_mul(&Q, y, ylen, cc);
@@ -786,6 +812,8 @@ const br_ec_impl br_ec_prime_i31 = {
        (uint32_t)0x03800000,
        &api_generator,
        &api_order,
+       &api_xoff,
        &api_mul,
+       &api_mulgen,
        &api_muladd
 };