From 97bfdd7eadd8786cdefe21614b750fc6e8c97ec2 Mon Sep 17 00:00:00 2001
From: Drew DeVault <sir@cmpwn.com>
Date: Wed, 25 Nov 2020 12:42:46 -0500
Subject: [PATCH] Tune defaults

---
 doc/mkchallenge.scd |  7 +------
 src/checkproof.c    |  5 +++--
 src/mkchallenge.c   | 25 +++++--------------------
 src/mkproof.c       |  8 ++++----
 4 files changed, 13 insertions(+), 32 deletions(-)

diff --git a/doc/mkchallenge.scd b/doc/mkchallenge.scd
index 78cc354..bc643b8 100644
--- a/doc/mkchallenge.scd
+++ b/doc/mkchallenge.scd
@@ -6,15 +6,10 @@ mkchallenge(1)
 
 # SYNOPSIS
 
-*mkchallenge* [-d _difficulty_]
+*mkchallenge*
 
 # DESCRIPTION
 
 *mkchallenge* generates a proof-of-work challenge and prints it to stdout. To
 solve the challenge, see *mkproof*(1). To check the solution, see
 *checkproof*(1).
-
-# OPTIONS
-
-*-d* _difficulty_
-	Sets the challenge difficulty. The default is 4.
diff --git a/src/checkproof.c b/src/checkproof.c
index 1ad15f7..e9da205 100644
--- a/src/checkproof.c
+++ b/src/checkproof.c
@@ -74,8 +74,9 @@ main(int argc, char *argv[])
 	r = argon2id_ctx(&context);
 	die(r != 0, "argon2id failed\n");
 
-	for (int i = 0; i < digits / 2; ++i) {
-		if (hash[i] != 0) {
+	for (int i = 0; i < digits; ++i) {
+		unsigned char n = hash[i / 2] & (i % 2 ? 0x0F : 0xF0);
+		if (n != 0) {
 			printf("proof: failed\n");
 			return 1;
 		}
diff --git a/src/mkchallenge.c b/src/mkchallenge.c
index 720d361..411e77d 100644
--- a/src/mkchallenge.c
+++ b/src/mkchallenge.c
@@ -6,35 +6,21 @@
 #include "util.h"
 
 #define ALGORITHM "argon2id"
-#define ITERATIONS 5
+#define ITERATIONS 10
 #define MEMORY 12
+#define DIGITS 5
 
 static void
 usage(char *argv_0)
 {
-	fprintf(stderr, "Usage: %s [-d difficulty]\n", argv_0);
 	exit(1);
 }
 
 int
 main(int argc, char *argv[])
 {
-	int digits = 4;
-
-	int c;
-	char *endptr;
-	while ((c = getopt(argc, argv, "d:")) != -1) {
-		switch (c) {
-		case 'd':
-			digits = strtoul(optarg, &endptr, 10);
-			if (*endptr) {
-				usage(argv[0]);
-			}
-			break;
-		}
-	}
-
-	if (optind < argc) {
+	if (argc != 1) {
+		fprintf(stderr, "Usage: %s\n", argv[0]);
 		usage(argv[0]);
 	}
 
@@ -44,8 +30,7 @@ main(int argc, char *argv[])
 
 	char seedhex[33];
 	enchex(seed, sizeof(seed), seedhex, sizeof(seedhex));
-
 	printf("%s:%d:%d:%d:%s\n", ALGORITHM,
-		ITERATIONS, MEMORY, digits * 2, seedhex);
+		ITERATIONS, MEMORY, DIGITS, seedhex);
 	return 0;
 }
diff --git a/src/mkproof.c b/src/mkproof.c
index e83f6e6..ce55a0f 100644
--- a/src/mkproof.c
+++ b/src/mkproof.c
@@ -70,7 +70,7 @@ main(int argc, char *argv[])
 	if (isatty(STDERR_FILENO)) {
 		// TODO: Provide a better estimate based on the difficulty
 		fprintf(stderr, "Generating a proof of work.\n");
-		fprintf(stderr, "This may take anywhere from tens of seconds to a few hours on slow computers.\n");
+		fprintf(stderr, "This may take anywhere from several minutes to a few hours on slow computers.\n");
 	}
 
 	unsigned long nattempts = 0;
@@ -87,8 +87,9 @@ main(int argc, char *argv[])
 		die(r != 0, "argon2id failed\n");
 
 		valid = 1;
-		for (int i = 0; i < digits / 2; ++i) {
-			if (hash[i] != 0) {
+		for (int i = 0; i < digits; ++i) {
+			unsigned char n = hash[i / 2] & (i % 2 ? 0x0F : 0xF0);
+			if (n != 0) {
 				valid = 0;
 				break;
 			}
@@ -102,6 +103,5 @@ main(int argc, char *argv[])
 	char proof[33];
 	enchex(password, sizeof(password), proof, sizeof(proof));
 	printf("%s\n", proof);
-
 	return 0;
 }