[API BREAK] Use a nonce-generation function instead of a nonce

src/bench_sign.c

@@ -10,15 +10,22 @@
 
 typedef struct {
     unsigned char msg[32];
-    unsigned char nonce[32];
     unsigned char key[32];
 } bench_sign_t;
 
+/** Very fast but insecure nonce generation function. Do not use for production code. */
+static int insecure_nonce_function(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, unsigned int count, const void *data) {
+   (void)data;
+   for (int i = 0; i < 8; i++) {
+       ((uint32_t*)nonce32)[i] = ((uint32_t*)msg32)[i] + ((uint32_t*)key32)[i] + count;
+   }
+   return 1;
+}
+
 static void bench_sign_setup(void* arg) {
     bench_sign_t *data = (bench_sign_t*)arg;
 
     for (int i = 0; i < 32; i++) data->msg[i] = i + 1;
-    for (int i = 0; i < 32; i++) data->nonce[i] = i + 33;
     for (int i = 0; i < 32; i++) data->key[i] = i + 65;
 }
 
@@ -28,9 +35,8 @@ static void bench_sign(void* arg) {
     unsigned char sig[64];
     for (int i=0; i<20000; i++) {
         int recid = 0;
-        CHECK(secp256k1_ecdsa_sign_compact(data->msg, sig, data->key, data->nonce, &recid));
+        secp256k1_ecdsa_sign_compact(data->msg, sig, data->key, insecure_nonce_function, NULL, &recid);
         for (int j = 0; j < 32; j++) {
-            data->nonce[j] = data->key[j];     /* Move former key to nonce  */
             data->msg[j] = sig[j];             /* Move former R to message. */
             data->key[j] = sig[j + 32];        /* Move former S to key.     */
         }