add secp256k1_ec_privkey_negate function and tests

Author: Thomas Kerin

secp256k1/php_secp256k1.h

@@ -42,6 +42,7 @@ PHP_FUNCTION(secp256k1_ecdsa_signature_serialize_der);
 PHP_FUNCTION(secp256k1_ecdsa_signature_normalize);
 
 PHP_FUNCTION(secp256k1_ec_seckey_verify);
+PHP_FUNCTION(secp256k1_ec_privkey_negate);
 PHP_FUNCTION(secp256k1_ec_pubkey_create);
 PHP_FUNCTION(secp256k1_ec_pubkey_combine);
 PHP_FUNCTION(secp256k1_ec_pubkey_parse);

secp256k1/secp256k1.c

@@ -133,6 +133,11 @@ ZEND_BEGIN_ARG_INFO(arginfo_secp256k1_ec_pubkey_create, 0)
     ZEND_ARG_INFO(0, secretKey)
 ZEND_END_ARG_INFO();
 
+ZEND_BEGIN_ARG_INFO(arginfo_secp256k1_ec_privkey_negate, 0)
+    ZEND_ARG_INFO(0, context)
+    ZEND_ARG_INFO(1, secKey)
+ZEND_END_ARG_INFO();
+
 ZEND_BEGIN_ARG_INFO(arginfo_secp256k1_ec_privkey_tweak_add, 0)
     ZEND_ARG_INFO(0, context)
     ZEND_ARG_INFO(1, seckey)
@@ -185,6 +190,7 @@ const zend_function_entry secp256k1_functions[] = {
         PHP_FE(secp256k1_ec_seckey_verify,                   arginfo_secp256k1_ec_seckey_verify)
 
         PHP_FE(secp256k1_ec_pubkey_create,                   arginfo_secp256k1_ec_pubkey_create)
+        PHP_FE(secp256k1_ec_privkey_negate,                  arginfo_secp256k1_ec_privkey_negate)
         PHP_FE(secp256k1_ec_pubkey_parse,                    arginfo_secp256k1_ec_pubkey_parse)
         PHP_FE(secp256k1_ec_pubkey_combine,                  arginfo_secp256k1_ec_pubkey_combine)
         PHP_FE(secp256k1_ec_pubkey_serialize,                arginfo_secp256k1_ec_pubkey_serialize)
@@ -747,6 +753,45 @@ PHP_FUNCTION(secp256k1_ec_pubkey_create)
 }
 /* }}} */
 
+/** Negates a private key in place.
+ *  Returns: 1 always
+ *  Args:   ctx:        pointer to a context object
+ *  In/Out: pubkey:     pointer to the public key to be negated (cannot be NULL)
+ */
+PHP_FUNCTION(secp256k1_ec_privkey_negate)
+{
+    zval *zCtx, *zPrivKey;
+    secp256k1_context *ctx;
+    unsigned char *newseckey;
+    int result;
+
+    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "rz/", &zCtx, &zPrivKey) == FAILURE) {
+        RETURN_FALSE;
+    }
+
+    if ((ctx = (secp256k1_context *)zend_fetch_resource2_ex(zCtx, SECP256K1_CTX_RES_NAME, le_secp256k1_ctx, -1)) == NULL) {
+        RETURN_FALSE;
+    }
+
+    if (Z_TYPE_P(zPrivKey) != IS_STRING) {
+        zend_throw_exception_ex(spl_ce_InvalidArgumentException, 0 TSRMLS_CC, "secp256k1_ec_privkey_negate(): Parameter 2 should be string");
+        return;
+    }
+
+    if (Z_STRLEN_P(zPrivKey) != SECRETKEY_LENGTH) {
+        zend_throw_exception_ex(spl_ce_InvalidArgumentException, 0 TSRMLS_CC, "secp256k1_ec_privkey_negate(): Parameter 2 should be 32 bytes");
+        return;
+    }
+
+    newseckey = (unsigned char *) emalloc(SECRETKEY_LENGTH);
+    memcpy(newseckey, Z_STRVAL_P(zPrivKey), SECRETKEY_LENGTH);
+    result = secp256k1_ec_privkey_negate(ctx, newseckey);
+    zval_dtor(zPrivKey);
+    ZVAL_STRINGL(zPrivKey, newseckey, SECRETKEY_LENGTH);
+
+    RETURN_LONG(result);
+}
+
 /* Parse a variable length public key into a public key resource */
 /** {{{ proto int secp256k1_ec_pubkey_parse(resource secp256k1_context, string publicKey)
  *  In:    ctx:          a secp256k1_context resource

secp256k1/tests/secp256k1_ec_privkey_negate_basic.phpt

@@ -0,0 +1,25 @@
+--TEST--
+secp256k1_ec_privkey_negate works
+--SKIPIF--
+<?php
+if (!extension_loaded("secp256k1")) print "skip extension not loaded";
+?>
+--FILE--
+<?php
+$ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+
+$privKey = pack("H*", "0000000000000000000000000000000000000000000000000000000000000001");
+$result = secp256k1_ec_privkey_negate($ctx, $privKey);
+echo $result . PHP_EOL;
+echo unpack("H*", $privKey)[1] . PHP_EOL;
+
+$result = secp256k1_ec_privkey_negate($ctx, $privKey);
+echo $result . PHP_EOL;
+echo unpack("H*", $privKey)[1] . PHP_EOL;
+
+?>
+--EXPECT--
+1
+fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364140
+1
+0000000000000000000000000000000000000000000000000000000000000001

secp256k1/tests/secp256k1_ec_privkey_negate_error1.phpt

@@ -0,0 +1,22 @@
+--TEST--
+secp256k1_ec_privkey_negate returns false if context is wrong resource type
+--SKIPIF--
+<?php
+if (!extension_loaded("secp256k1")) print "skip extension not loaded";
+?>
+--FILE--
+<?php
+
+set_error_handler(function($code, $str) { echo $str . PHP_EOL; });
+
+$keyTweak = str_repeat("A", 32);
+$context = tmpfile();
+$result = secp256k1_ec_privkey_negate($context, $keyTweak);
+echo gettype($result) . PHP_EOL;
+echo ($result ? "true" : "false") . PHP_EOL;
+
+?>
+--EXPECT--
+secp256k1_ec_privkey_negate(): supplied resource is not a valid secp256k1_context resource
+boolean
+false

secp256k1/tests/secp256k1_ec_privkey_negate_error2.phpt

@@ -0,0 +1,20 @@
+--TEST--
+secp256k1_ec_privkey_negate returns false if parameter parsing fails
+--SKIPIF--
+<?php
+if (!extension_loaded("secp256k1")) print "skip extension not loaded";
+?>
+--FILE--
+<?php
+
+set_error_handler(function($code, $str) { echo $str . PHP_EOL; });
+
+$ctx1 = secp256k1_ec_privkey_negate();
+echo gettype($ctx1) . PHP_EOL;
+echo ($ctx1 ? "true" : "false") . PHP_EOL;
+
+?>
+--EXPECT--
+secp256k1_ec_privkey_negate() expects exactly 2 parameters, 0 given
+boolean
+false

secp256k1/tests/secp256k1_ec_privkey_negate_error3.phpt

@@ -0,0 +1,20 @@
+--TEST--
+secp256k1_ec_privkey_negate throws exception if privKey is not a string
+--SKIPIF--
+<?php
+if (!extension_loaded("secp256k1")) print "skip extension not loaded";
+?>
+--FILE--
+<?php
+$ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+
+$privKey = 1;
+try {
+    secp256k1_ec_privkey_negate($ctx, $privKey);
+} catch (\Exception $e) {
+    echo $e->getMessage() . PHP_EOL;
+}
+
+?>
+--EXPECT--
+secp256k1_ec_privkey_negate(): Parameter 2 should be string

secp256k1/tests/secp256k1_ec_privkey_negate_error4.phpt

@@ -0,0 +1,20 @@
+--TEST--
+secp256k1_ec_privkey_negate throws exception if privKey is not 32 bytes
+--SKIPIF--
+<?php
+if (!extension_loaded("secp256k1")) print "skip extension not loaded";
+?>
+--FILE--
+<?php
+$ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+
+$privKey = "1234abcd";
+try {
+    secp256k1_ec_privkey_negate($ctx, $privKey);
+} catch (\Exception $e) {
+    echo $e->getMessage() . PHP_EOL;
+}
+
+?>
+--EXPECT--
+secp256k1_ec_privkey_negate(): Parameter 2 should be 32 bytes