RT2943: Check sizes if -iv and -K arguments

RT2943 only complains about the incorrect check of -K argument size,
we might as well do the same thing with the -iv argument.

Before this, we only checked that the given argument wouldn't give a
bitstring larger than EVP_MAX_KEY_LENGTH.  we can be more precise and
check against the size of the actual cipher used.
Reviewed-by: NRich Salz <rsalz@openssl.org>

apps/enc.c

@@ -459,9 +459,14 @@ int enc_main(int argc, char **argv)
             else
                 OPENSSL_cleanse(str, strlen(str));
         }
-        if ((hiv != NULL) && !set_hex(hiv, iv, sizeof iv)) {
-            BIO_printf(bio_err, "invalid hex iv value\n");
-            goto end;
+        if (hiv != NULL) {
+            int siz = EVP_CIPHER_iv_length(cipher);
+            if (siz == 0) {
+                BIO_printf(bio_err, "warning: iv not use by this cipher\n");
+            } else if (!set_hex(hiv, iv, sizeof iv)) {
+                BIO_printf(bio_err, "invalid hex iv value\n");
+                goto end;
+            }
         }
         if ((hiv == NULL) && (str == NULL)
             && EVP_CIPHER_iv_length(cipher) != 0) {
@@ -473,7 +478,7 @@ int enc_main(int argc, char **argv)
             BIO_printf(bio_err, "iv undefined\n");
             goto end;
         }
-        if ((hkey != NULL) && !set_hex(hkey, key, sizeof key)) {
+        if ((hkey != NULL) && !set_hex(hkey, key, EVP_CIPHER_key_length(cipher))) {
             BIO_printf(bio_err, "invalid hex key value\n");
             goto end;
         }