PROTOTYPE Split headers to make it possible to use only prealloc API

contrib/lax_der_privatekey_parsing.h

@@ -43,8 +43,7 @@ extern "C" {
 /** Export a private key in DER format.
  *
  *  Returns: 1 if the private key was valid.
- *  Args: ctx:        pointer to a context object, initialized for signing (cannot
- *                    be NULL)
+ *  Args: ctx:        pointer to a context object (not secp256k1_context_static).
  *  Out: privkey:     pointer to an array for storing the private key in BER.
  *                    Should have space for 279 bytes, and cannot be NULL.
  *       privkeylen:  Pointer to an int where the length of the private key in

doc/CHANGELOG.md

@@ -9,6 +9,13 @@ Each change falls into one of the following categories: Added, Changed, Deprecat
 ### Changed
  - Enable modules schnorrsig, extrakeys and ECDH by default in ./configure
 
+### Deprecated
+ - Deprecated context flags `SECP256K1_CONTEXT_VERIFY` and `SECP256K1_CONTEXT_NONE`. Use `SECP256K1_CONTEXT_DEFAULT` instead.
+ - Renamed `secp256k1_context_no_precomp` to `secp256k1_context_static`.
+
+### Added
+ - Added `secp256k1_selftest`, to be used in conjunction with `secp256k1_context_static`.
+
 ## [MAJOR.MINOR.PATCH] - YYYY-MM-DD
 
 ### Added/Changed/Deprecated/Removed/Fixed/Security

examples/ecdh.c

@@ -11,7 +11,7 @@
 #include <assert.h>
 #include <string.h>
 
-#include <secp256k1.h>
+#include <secp256k1_preallocated.h>
 #include <secp256k1_ecdh.h>
 
 #include "random.h"
@@ -35,7 +35,8 @@ int main(void) {
      * a context with the SECP256K1_CONTEXT_SIGN flag.
      * (The docs for `secp256k1_ecdh` don't require any special context, just
      * some initialized context) */
-    secp256k1_context* ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+    unsigned char mem[1000];
+    secp256k1_context* ctx = secp256k1_context_preallocated_create(mem, SECP256K1_CONTEXT_SIGN);
     if (!fill_random(randomize, sizeof(randomize))) {
         printf("Failed to generate randomness\n");
         return 1;
@@ -109,7 +110,7 @@ int main(void) {
     print_hex(shared_secret1, sizeof(shared_secret1));
 
     /* This will clear everything from the context and free the memory */
-    secp256k1_context_destroy(ctx);
+    secp256k1_context_preallocated_destroy(ctx);
 
     /* It's best practice to try to clear secrets from memory after using them.
      * This is done because some bugs can allow an attacker to leak memory, for

examples/ecdsa.c

@@ -38,12 +38,8 @@ int main(void) {
     int return_val;
     secp256k1_pubkey pubkey;
     secp256k1_ecdsa_signature sig;
-    /* The specification in secp256k1.h states that `secp256k1_ec_pubkey_create` needs
-     * a context object initialized for signing and `secp256k1_ecdsa_verify` needs
-     * a context initialized for verification, which is why we create a context
-     * for both signing and verification with the SECP256K1_CONTEXT_SIGN and
-     * SECP256K1_CONTEXT_VERIFY flags. */
-    secp256k1_context* ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY);
+    /* Before we can call actual API functions, we need to create a "context". */
+    secp256k1_context* ctx = secp256k1_context_create(SECP256K1_CONTEXT_DEFAULT);
     if (!fill_random(randomize, sizeof(randomize))) {
         printf("Failed to generate randomness\n");
         return 1;

examples/schnorr.c

@@ -30,12 +30,8 @@ int main(void) {
     int return_val;
     secp256k1_xonly_pubkey pubkey;
     secp256k1_keypair keypair;
-    /* The specification in secp256k1_extrakeys.h states that `secp256k1_keypair_create`
-     * needs a context object initialized for signing. And in secp256k1_schnorrsig.h
-     * they state that `secp256k1_schnorrsig_verify` needs a context initialized for
-     * verification, which is why we create a context for both signing and verification
-     * with the SECP256K1_CONTEXT_SIGN and SECP256K1_CONTEXT_VERIFY flags. */
-    secp256k1_context* ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY);
+    /* Before we can call actual API functions, we need to create a "context". */
+    secp256k1_context* ctx = secp256k1_context_create(SECP256K1_CONTEXT_DEFAULT);
     if (!fill_random(randomize, sizeof(randomize))) {
         printf("Failed to generate randomness\n");
         return 1;