add ndb_sign_id and ndb_calculate_id

also do this on finalization optionally

Author: jb55

.gitignore

@@ -9,3 +9,5 @@ test_contacts_ndb_note
 bench
 configurator
 config.h
+libsecp256k1.a
+.direnv/

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "deps/secp256k1"]
+	path = deps/secp256k1
+	url = https://github.com/bitcoin-core/secp256k1

Makefile

@@ -1,7 +1,11 @@
 CFLAGS = -Wall -Wno-unused-function -Werror -O2 -g
-HEADERS = sha256.h nostrdb.h cursor.h hex.h jsmn.h config.h sha256.h
+HEADERS = sha256.h nostrdb.h cursor.h hex.h jsmn.h config.h sha256.h random.h
 SRCS = nostrdb.c sha256.c 
-DEPS = $(SRCS) $(HEADERS)
+LDS = $(SRCS) $(ARS)
+ARS = libsecp256k1.a
+DEPS = $(SRCS) $(HEADERS) $(ARS)
+PREFIX ?= /usr/local
+SUBMODULES = deps/secp256k1
 
 check: test
 	./test
@@ -21,11 +25,31 @@ configurator: configurator.c
 config.h: configurator
 	./configurator > $@
 
+deps/secp256k1/.git:
+	@devtools/refresh-submodules.sh $(SUBMODULES)
+
+deps/secp256k1/include/secp256k1.h: deps/secp256k1/.git
+
+deps/secp256k1/configure: deps/secp256k1/.git
+	cd deps/secp256k1; \
+	./autogen.sh
+
+deps/secp256k1/.libs/libsecp256k1.a: deps/secp256k1/config.log
+	cd deps/secp256k1; \
+	make -j libsecp256k1.la
+
+deps/secp256k1/config.log: deps/secp256k1/configure
+	cd deps/secp256k1; \
+	./configure --disable-shared --enable-module-ecdh --enable-module-schnorrsig --enable-module-extrakeys
+
+libsecp256k1.a: deps/secp256k1/.libs/libsecp256k1.a
+	cp $< $@
+
 bench: bench.c $(DEPS)
-	$(CC) $(CFLAGS) bench.c $(SRCS) -o $@
+	$(CC) $(CFLAGS) bench.c $(LDS) -o $@
 
 test: test.c $(DEPS)
-	$(CC) $(CFLAGS) test.c $(SRCS) -o $@
+	$(CC) $(CFLAGS) test.c $(LDS) -o $@
 
 %.o: %.c
 	$(CC) $(CFLAGS)

deps/secp256k1

@@ -0,0 +1,42 @@
+#! /bin/sh
+
+if [ $# = 0 ]; then
+    echo "Usage: $0 <submoduledir1>..." >&2
+    exit 1
+fi
+
+# If no git dir (or, if we're a submodule, git file), forget it.
+[ -e .git ] || exit 0
+
+# git submodule can't run in parallel.  Really.
+# Wait for it to finish if in parallel.
+if ! mkdir .refresh-submodules 2>/dev/null ; then
+    # If we don't make progress in ~60 seconds, force delete and retry.
+    LIMIT=$((50 + $$ % 20))
+    i=0
+    while [ $i -lt $LIMIT ]; do
+	[ -d .refresh-submodules ] || exit 0
+	sleep 1
+	i=$((i + 1))
+    done
+    rmdir .refresh-submodules
+    exec "$0" "$@" || exit 1
+fi
+
+trap "rmdir .refresh-submodules" EXIT
+
+# Be a little careful here, since we do rm -rf!
+for m in "$@"; do
+    if ! grep -q "path = $m\$" .gitmodules; then
+	echo "$m is not a submodule!" >&2
+	exit 1
+    fi
+done
+
+# git submodule can segfault.  Really.
+if [ "$(git submodule status "$@" | grep -c '^ ')" != $# ]; then
+    echo Reinitializing submodules "$@" ...
+    git submodule sync "$@"
+    rm -rf "$@"
+    git submodule update --init --recursive "$@"
+fi

devtools/refresh-submodules.sh

@@ -3,6 +3,7 @@
 #include "jsmn.h"
 #include "hex.h"
 #include "cursor.h"
+#include "random.h"
 #include "sha256.h"
 #include <stdlib.h>
 #include <limits.h>
@@ -25,7 +26,6 @@ int ndb_builder_init(struct ndb_builder *builder, unsigned char *buf,
 		     int bufsize)
 {
 	struct ndb_note *note;
-	struct cursor mem;
 	int half, size, str_indices_size;
 
 	// come on bruh
@@ -39,14 +39,14 @@ int ndb_builder_init(struct ndb_builder *builder, unsigned char *buf,
 	//debug("size %d half %d str_indices %d\n", size, half, str_indices_size);
 
 	// make a safe cursor of our available memory
-	make_cursor(buf, buf + bufsize, &mem);
+	make_cursor(buf, buf + bufsize, &builder->mem);
 
 	note = builder->note = (struct ndb_note *)buf;
 
 	// take slices of the memory into subcursors
-	if (!(cursor_slice(&mem, &builder->note_cur, half) &&
-	      cursor_slice(&mem, &builder->strings, half) &&
-	      cursor_slice(&mem, &builder->str_indices, str_indices_size))) {
+	if (!(cursor_slice(&builder->mem, &builder->note_cur, half) &&
+	      cursor_slice(&builder->mem, &builder->strings, half) &&
+	      cursor_slice(&builder->mem, &builder->str_indices, str_indices_size))) {
 		return 0;
 	}
 
@@ -265,7 +265,7 @@ static int ndb_event_commitment(struct ndb_note *ev, unsigned char *buf, int buf
 	return cur.p - cur.start;
 }
 
-int ndb_calculate_note_id(struct ndb_note *note, unsigned char *buf, int buflen) {
+int ndb_calculate_id(struct ndb_note *note, unsigned char *buf, int buflen) {
 	int len;
 
 	if (!(len = ndb_event_commitment(note, buf, buflen)))
@@ -278,12 +278,50 @@ int ndb_calculate_note_id(struct ndb_note *note, unsigned char *buf, int buflen)
 	return 1;
 }
 
+int ndb_sign_id(secp256k1_context *ctx, struct ndb_keypair *keypair,
+		unsigned char id[32], unsigned char sig[64])
+{
+	unsigned char aux[32];
+
+	if (!fill_random(aux, sizeof(aux)))
+		return 0;
+
+	return secp256k1_schnorrsig_sign32(ctx, sig, id, &keypair->pair, aux);
+}
+
+int ndb_create_keypair(secp256k1_context *ctx, struct ndb_keypair *key)
+{
+	secp256k1_xonly_pubkey pubkey;
+
+	/* Try to create a keypair with a valid context, it should only
+	 * fail if the secret key is zero or out of range. */
+	if (!secp256k1_keypair_create(ctx, &key->pair, key->secret))
+		return 0;
+
+	if (!secp256k1_keypair_xonly_pub(ctx, &pubkey, NULL, &key->pair))
+		return 0;
+
+	/* Serialize the public key. Should always return 1 for a valid public key. */
+	return secp256k1_xonly_pubkey_serialize(ctx, key->pubkey, &pubkey);
+}
 
-int ndb_builder_finalize(struct ndb_builder *builder, struct ndb_note **note)
+int ndb_decode_key(secp256k1_context *ctx, const char *secstr,
+		   struct ndb_keypair *keypair)
+{
+	if (!hex_decode(secstr, strlen(secstr), keypair->secret, 32)) {
+		fprintf(stderr, "could not hex decode secret key\n");
+		return 0;
+	}
+
+	return ndb_create_keypair(ctx, keypair);
+}
+
+int ndb_builder_finalize(struct ndb_builder *builder, struct ndb_note **note,
+			 struct ndb_keypair *keypair)
 {
 	int strings_len = builder->strings.p - builder->strings.start;
-	unsigned char *end = builder->note_cur.p + strings_len;
-	int total_size = end - builder->note_cur.start;
+	unsigned char *note_end = builder->note_cur.p + strings_len;
+	int total_size = note_end - builder->note_cur.start;
 
 	// move the strings buffer next to the end of our ndb_note
 	memmove(builder->note_cur.p, builder->strings.start, strings_len);
@@ -296,6 +334,22 @@ int ndb_builder_finalize(struct ndb_builder *builder, struct ndb_note **note)
 
 	*note = builder->note;
 
+	// generate id and sign if we're building this manually
+	if (keypair) {
+		// use the remaining memory for building our id buffer
+		unsigned char *end   = builder->mem.end;
+		unsigned char *start = (unsigned char*)(*note) + total_size;
+
+		if (!ndb_calculate_id(*note, start, end - start))
+			return 0;
+
+		secp256k1_context *ctx =
+			secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+
+		if (!ndb_sign_id(ctx, keypair, (*note)->id, (*note)->sig))
+			return 0;
+	}
+
 	return total_size;
 }
 
@@ -626,7 +680,7 @@ int ndb_note_from_json(const char *json, int len, struct ndb_note **note,
 			// sig
 			tok = &parser.toks[i+1];
 			hex_decode(json + tok->start, toksize(tok), hexbuf, sizeof(hexbuf));
-			ndb_builder_set_signature(&parser.builder, hexbuf);
+			ndb_builder_set_sig(&parser.builder, hexbuf);
 		} else if (start[0] == 'k' && jsoneq(json, tok, tok_len, "kind")) {
 			// kind
 			tok = &parser.toks[i+1];
@@ -668,7 +722,7 @@ int ndb_note_from_json(const char *json, int len, struct ndb_note **note,
 		}
 	}
 
-	return ndb_builder_finalize(&parser.builder, note);
+	return ndb_builder_finalize(&parser.builder, note, NULL);
 }
 
 void ndb_builder_set_pubkey(struct ndb_builder *builder, unsigned char *pubkey)
@@ -681,10 +735,9 @@ void ndb_builder_set_id(struct ndb_builder *builder, unsigned char *id)
 	memcpy(builder->note->id, id, 32);
 }
 
-void ndb_builder_set_signature(struct ndb_builder *builder,
-			       unsigned char *signature)
+void ndb_builder_set_sig(struct ndb_builder *builder, unsigned char *sig)
 {
-	memcpy(builder->note->signature, signature, 64);
+	memcpy(builder->note->sig, sig, 64);
 }
 
 void ndb_builder_set_kind(struct ndb_builder *builder, uint32_t kind)

nostrdb.c

@@ -4,6 +4,10 @@
 #include <inttypes.h>
 #include "cursor.h"
 
+#include "secp256k1.h"
+#include "secp256k1_ecdh.h"
+#include "secp256k1_schnorrsig.h"
+
 struct ndb_str {
 	unsigned char flag;
 	union {
@@ -12,6 +16,13 @@ struct ndb_str {
 	};
 };
 
+struct ndb_keypair {
+	unsigned char pubkey[32];
+	unsigned char secret[32];
+	secp256k1_keypair pair;
+};
+
+
 // these must be byte-aligned, they are directly accessing the serialized data
 // representation
 #pragma pack(push, 1)
@@ -47,7 +58,7 @@ struct ndb_note {
 	unsigned char padding[3]; // keep things aligned
 	unsigned char id[32];
 	unsigned char pubkey[32];
-	unsigned char signature[64];
+	unsigned char sig[64];
 
 	uint32_t created_at;
 	uint32_t kind;
@@ -62,6 +73,7 @@ struct ndb_note {
 #pragma pack(pop)
 
 struct ndb_builder {
+	struct cursor mem;
 	struct cursor note_cur;
 	struct cursor strings;
 	struct cursor str_indices;
@@ -78,22 +90,23 @@ struct ndb_iterator {
 };
 
 // HELPERS
-int ndb_calculate_note_id(struct ndb_note *note, unsigned char *buf, int buflen);
-// BYE HELPERS
+int ndb_calculate_id(struct ndb_note *note, unsigned char *buf, int buflen);
+int ndb_sign_id(secp256k1_context *ctx, struct ndb_keypair *keypair, unsigned char id[32], unsigned char sig[64]);
+int ndb_create_keypair(secp256k1_context *ctx, struct ndb_keypair *key);
+int ndb_decode_key(secp256k1_context *ctx, const char *secstr, struct ndb_keypair *keypair);
 
-// HI BUILDER
+// BUILDER
 int ndb_note_from_json(const char *json, int len, struct ndb_note **, unsigned char *buf, int buflen);
 int ndb_builder_init(struct ndb_builder *builder, unsigned char *buf, int bufsize);
-int ndb_builder_finalize(struct ndb_builder *builder, struct ndb_note **note);
+int ndb_builder_finalize(struct ndb_builder *builder, struct ndb_note **note, struct ndb_keypair *privkey);
 int ndb_builder_set_content(struct ndb_builder *builder, const char *content, int len);
 void ndb_builder_set_created_at(struct ndb_builder *builder, uint32_t created_at);
-void ndb_builder_set_signature(struct ndb_builder *builder, unsigned char *signature);
+void ndb_builder_set_sig(struct ndb_builder *builder, unsigned char *sig);
 void ndb_builder_set_pubkey(struct ndb_builder *builder, unsigned char *pubkey);
 void ndb_builder_set_id(struct ndb_builder *builder, unsigned char *id);
 void ndb_builder_set_kind(struct ndb_builder *builder, uint32_t kind);
 int ndb_builder_new_tag(struct ndb_builder *builder);
 int ndb_builder_push_tag_str(struct ndb_builder *builder, const char *str, int len);
-// BYE BUILDER
 
 static inline struct ndb_str ndb_note_str(struct ndb_note *note,
 					  union ndb_packed_str *pstr)
@@ -116,17 +129,6 @@ static inline struct ndb_str ndb_tag_str(struct ndb_note *note,
 	return ndb_note_str(note, &tag->strs[ind]);
 }
 
-static inline int ndb_tag_matches_char(struct ndb_note *note,
-				       struct ndb_tag *tag, int ind, char c)
-{
-	struct ndb_str str = ndb_tag_str(note, tag, ind);
-	if (str.str[0] == '\0')
-		return 0;
-	else if (str.str[0] == c)
-		return 1;
-	return 0;
-}
-
 static inline struct ndb_str ndb_iter_tag_str(struct ndb_iterator *iter,
 					      int ind)
 {
@@ -143,9 +145,9 @@ static inline unsigned char * ndb_note_pubkey(struct ndb_note *note)
 	return note->pubkey;
 }
 
-static inline unsigned char * ndb_note_signature(struct ndb_note *note)
+static inline unsigned char * ndb_note_sig(struct ndb_note *note)
 {
-	return note->signature;
+	return note->sig;
 }
 
 static inline uint32_t ndb_note_created_at(struct ndb_note *note)