examples: Switch to DEFAULT contexts

Author: real-or-random

examples/ecdh.c

@@ -30,12 +30,8 @@ int main(void) {
     secp256k1_pubkey pubkey1;
     secp256k1_pubkey pubkey2;
 
-    /* The specification in secp256k1.h states that `secp256k1_ec_pubkey_create`
-     * needs a context object initialized for signing, which is why we create
-     * 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);
+    /* 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/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;