Completely remove random device options

This option adds needless complexity. Just hardcode /dev/urandom.

README.md

@@ -243,21 +243,6 @@ The compile-time options below also apply to this amalgamation build.
 Various options and defaults can be configured at compile time using C
 defines (`-D...`).
 
-#### `ENCHIVE_RANDOM_DEVICE`
-
-For unix-like systems, this is the default source of entropy when
-creating keys and IVs. The default value is `/dev/urandom`. You could
-set this to `/dev/random`, though that's [pointless][djb] and [a waste
-of time][myths]. It can be changed at run time with `--random-device`.
-
-In the future, Enchive may first try `getrandom(2)` / `getentropy(2)`.
-
-#### `ENCHIVE_OPTION_RANDOM_DEVICE`
-
-Whether or not the `--random-device` option should be available. This
-option is 0 by default on Windows, where Enchive always uses a
-[Cryptographic Service Provider][csp].
-
 #### `ENCHIVE_OPTION_AGENT`
 
 Whether to expose the `--agent` and `--no-agent` option. This option

config.h

@@ -11,10 +11,6 @@
 #  define ENCHIVE_FORMAT_VERSION 3
 #endif
 
-#ifndef ENCHIVE_RANDOM_DEVICE
-#  define ENCHIVE_RANDOM_DEVICE /dev/urandom
-#endif
-
 #ifndef ENCHIVE_KEY_DERIVE_ITERATIONS
 #  define ENCHIVE_KEY_DERIVE_ITERATIONS 25  /* 32MB */
 #endif
@@ -23,14 +19,6 @@
 #  define ENCHIVE_SECKEY_DERIVE_ITERATIONS 29 /* 512MB */
 #endif
 
-#ifndef ENCHIVE_OPTION_RANDOM_DEVICE
-#  if defined(__unix__) || defined(__APPLE__)
-#    define ENCHIVE_OPTION_RANDOM_DEVICE 1
-#  else
-#    define ENCHIVE_OPTION_RANDOM_DEVICE 0
-#  endif
-#endif
-
 #ifndef ENCHIVE_OPTION_AGENT
 #  if defined(__unix__) || defined(__APPLE__)
 #    define ENCHIVE_OPTION_AGENT 1

enchive.1

@@ -7,7 +7,6 @@ enchive \- personal archive encryption
 .HP 8
 .B enchive
 [\-\fBa\fR[\fIseconds\fR]|\fB\-A\fR]
-[\fB\-r\ \fIdevice\fR]
 [\fB\-p\ \fIpubkey\fR]
 [\fB\-s\ \fIseckey\fR]
 [\fB\-\-version\fR]
@@ -52,9 +51,6 @@ Do not start the key agent (default).
 \fB\-p, \-\-pubkey\fR \fIfile\fR
 Specifies the public key file to use for encryption.
 .TP
-\fB\-r\fR, \fB\-\-random\-device\fR \fIdevice\fR
-Use \fIdevice\fR as an entropy source instead of \fB/dev/urandom\fR.
-.TP
 \fB\-s, \-\-seckey\fR \fIfile\fR
 Specifies the secret key file to use for decryption.
 .TP
@@ -67,7 +63,7 @@ Print a synopsis of the command line interface.
 Any unique prefix for a command is accepted. For example, the command \fBa\fR would mean \fBarchive\fR.
 .TP
 \fBkeygen\fR [\fIOPTION\fR]...
-Generates a new keypair either from the random device or a passphrase.
+Generates a new keypair either from system entropy or a passphrase.
 .RS 4
 .TP
 \fB\-d\fR[\fIN\fR], \fB\-\-derive\fR[=\fIN\fR]

src/docs.h

@@ -3,12 +3,7 @@ static const char *docs_usage[] = {
 #if ENCHIVE_OPTION_AGENT
 "              [-a|--agent[=seconds]] [-A|--no-agent]",
 #endif
-#if ENCHIVE_OPTION_RANDOM_DEVICE
+"              [--version] [--help]",
-"              [-r|--random-device <file>] "
-#else
-"              "
-#endif
-"[--version] [--help]",
 "              <command> [args]",
 "",
 "Commands (unique prefixes accepted):",
@@ -29,10 +24,6 @@ static const char *docs_usage[] = {
     " (default)",
 #  endif
 #endif
-#if ENCHIVE_OPTION_RANDOM_DEVICE
-"  -r, --random-device <dev>  device for secure entropy ["
-    STR(ENCHIVE_RANDOM_DEVICE) "]",
-#endif
 "  --version                  display version information",
 "  --help                     display this usage information",
 "",

src/enchive.c

@@ -610,14 +610,12 @@ key_derive(const char *passphrase, u8 *buf, int iexp, const u8 *salt)
 static void secure_entropy(void *buf, size_t len);
 
 #if defined(__unix__) || defined(__APPLE__)
-static char *global_random_device = STR(ENCHIVE_RANDOM_DEVICE);
-
 static void
 secure_entropy(void *buf, size_t len)
 {
-    FILE *r = fopen(global_random_device, "rb");
+    FILE *r = fopen("/dev/urandom", "rb");
     if (!r)
-        fatal("failed to open %s", global_random_device);
+        fatal("failed to open %s", "/dev/urandom");
     if (!fread(buf, len, 1, r))
         fatal("failed to gather entropy");
     fclose(r);
@@ -1402,9 +1400,6 @@ main(int argc, char **argv)
 #if ENCHIVE_OPTION_AGENT
         {"agent",         'a', OPTPARSE_OPTIONAL},
         {"no-agent",      'A', OPTPARSE_NONE},
-#endif
-#if ENCHIVE_OPTION_RANDOM_DEVICE
-        {"random-device", 'r', OPTPARSE_REQUIRED},
 #endif
         {"pubkey",        'p', OPTPARSE_REQUIRED},
         {"seckey",        's', OPTPARSE_REQUIRED},
@@ -1437,11 +1432,6 @@ main(int argc, char **argv)
             case 'A':
                 global_agent_timeout = 0;
                 break;
-#endif
-#if ENCHIVE_OPTION_RANDOM_DEVICE
-            case 'r':
-                global_random_device = options->optarg;
-                break;
 #endif
             case 'p':
                 global_pubkey = options->optarg;