uencrypt: support all available ciphers

Modify uencrypt to support any cipher provided by ssl library.

Original tool supported only AES-128-CBC to decrypt the config
mtd of Arcadyan WG430223/WG443223.

TP-Link Deco S4 has mtd configuration encrypted with DES-ECB,
so make the cipher generic to support both routers.

Signed-off-by: Nick French <nickfrench@gmail.com>
Reviewed-by: Eneas U de Queiroz >cotequeiroz@gmail.com>

2 files changed, 52 insertions, 18 deletions

diff --git a/package/utils/uencrypt/Makefile b/package/utils/uencrypt/Makefile
index 77fdf64e0e..9307f97b6e 100644
--- a/package/utils/uencrypt/Makefile
+++ b/package/utils/uencrypt/Makefile
@@ -22,16 +22,17 @@ CMAKE_OPTIONS+=$(if $(CONFIG_UENCRYPT_WOLFSSL),-DUSE_WOLFSSL=1)
 define Package/uencrypt
   SECTION:=utils
   CATEGORY:=Base system
-  TITLE:=Decryption utility for Arcadyan WG4xx223
-  DEPENDS:=@TARGET_ramips_mt7621 +UENCRYPT_WOLFSSL:libwolfssl +UENCRYPT_OPENSSL:libopenssl
+  TITLE:=Decryption utility for Arcadyan WG4xx223 and TP-Link Deco S4
+  DEPENDS:=+UENCRYPT_WOLFSSL:libwolfssl +UENCRYPT_OPENSSL:libopenssl
 endef
 
 define Package/uencrypt/description
-  This is a small AES-128-CBC encrypton/decryption program.
-  Even though it can be used for regular encryption and
-  decryption operations using AES-128-CBC, it is included
-  here to unencrypt the configuration from mtd on Arcadyan
-  WG430223 and WG443223 routers.
+  This is a small encrypton/decryption program. It defaults
+  to AES-128-CBC, but supports any encryption provided by
+  the available openssl/wolfssl library. Even though it can
+  be used for regular encryption and decryption operations,
+  it is included here to unencrypt the configuration from mtd
+  on Arcadyan WG430223/WG443223 and TP-Link Deco S4 routers
 endef
 
 define Package/uencrypt/config
diff --git a/package/utils/uencrypt/src/uencrypt.c b/package/utils/uencrypt/src/uencrypt.c
index c4199b057a..ab9a202cec 100644
--- a/package/utils/uencrypt/src/uencrypt.c
+++ b/package/utils/uencrypt/src/uencrypt.c
@@ -5,6 +5,7 @@
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 #ifdef USE_WOLFSSL
@@ -14,7 +15,7 @@
 # include <openssl/evp.h>
 #endif
 
-int do_crypt(FILE *infile, FILE *outfile, const char *key, const char *iv,
+int do_crypt(FILE *infile, FILE *outfile, const EVP_CIPHER *cipher, const char *key, const char *iv,
 	     int enc, int padding)
 {
     EVP_CIPHER_CTX *ctx;
@@ -22,7 +23,7 @@ int do_crypt(FILE *infile, FILE *outfile, const char *key, const char *iv,
     int inlen, outlen;
 
     ctx = EVP_CIPHER_CTX_new();
-    EVP_CipherInit_ex(ctx, EVP_aes_128_cbc(), NULL, key, iv, enc);
+    EVP_CipherInit_ex(ctx, cipher, NULL, key, iv, enc);
     EVP_CIPHER_CTX_set_padding(ctx, padding);
 
     for (;;) {
@@ -53,9 +54,27 @@ static void check_enc_dec(const int enc)
     exit(EXIT_FAILURE);
 }
 
+#ifndef USE_WOLFSSL
+static void print_ciphers(const OBJ_NAME *name,void *arg) {
+    fprintf(arg, "\t%s\n", name->name);
+}
+#endif
+
+static void check_cipher(const EVP_CIPHER *cipher)
+{
+    if (cipher == NULL) {
+        fprintf(stderr, "Error: invalid cipher: %s.\n", optarg);
+#ifndef USE_WOLFSSL
+        fprintf(stderr, "Supported ciphers: \n", optarg);
+        OBJ_NAME_do_all_sorted(OBJ_NAME_TYPE_CIPHER_METH, print_ciphers, stderr);
+#endif
+        exit(EXIT_FAILURE);
+    }
+}
+
 static void show_usage(const char* name)
 {
-    fprintf(stderr, "Usage: %s: [-d | -e] [-n] -k key -i iv\n"
+    fprintf(stderr, "Usage: %s: [-d | -e] [-n] -k key [-i iv] [-c cipher]\n"
 		    "-d = decrypt; -e = encrypt; -n = no padding\n", name);
 }
 
@@ -67,10 +86,19 @@ int main(int argc, char *argv[])
     long len;
     int opt;
     int padding = 1;
+    int need_iv = 1;
+    const EVP_CIPHER *cipher = EVP_aes_128_cbc();
     int ret;
 
-    while ((opt = getopt(argc, argv, "dei:k:n")) != -1) {
+    while ((opt = getopt(argc, argv, "c:dei:k:n")) != -1) {
 	switch (opt) {
+	case 'c':
+	    cipher = EVP_get_cipherbyname(optarg);
+	    check_cipher(cipher);
+	    int arglen = strlen(optarg);
+	    if (arglen > 3 && strncmp(optarg+arglen-3, "ecb", 3) == 0) //if ends with "ecb"
+	        need_iv = 0;
+	    break;
 	case 'd':
 	    check_enc_dec(enc);
 	    enc = 0;
@@ -81,16 +109,16 @@ int main(int argc, char *argv[])
 	    break;
 	case 'i':
 	    iv = OPENSSL_hexstr2buf((const char *)optarg, &len);
-	    if (iv == NULL || len != 16) {
-		fprintf(stderr, "Error setting IV to %s. The IV should be 16 bytes, encoded in hex.\n",
+	    if (iv == NULL) {
+		fprintf(stderr, "Error setting IV to %s. The IV should be encoded in hex.\n",
 			optarg);
 		exit(EINVAL);
 	    }
 	    break;
 	case 'k':
 	    key = OPENSSL_hexstr2buf((const char *)optarg, &len);
-	    if (key == NULL || len != 16) {
-		fprintf(stderr, "Error setting key to %s. The key should be 16 bytes, encoded in hex.\n",
+	    if (key == NULL) {
+		fprintf(stderr, "Error setting key to %s. The key should be encoded in hex.\n",
 			optarg);
 		exit(EINVAL);
 	    }
@@ -103,12 +131,17 @@ int main(int argc, char *argv[])
 	    exit(EINVAL);
 	}
     }
-    if (iv == NULL || key == NULL) {
-	fprintf(stderr, "Error: %s not set.\n", key ? "iv" : (iv ? "key" : "key and iv"));
+    if (need_iv && iv == NULL) {
+        fprintf(stderr, "Error: iv not set.\n");
+        show_usage(argv[0]);
+        exit(EXIT_FAILURE);
+    }
+    if (key == NULL) {
+	fprintf(stderr, "Error: key not set.\n");
 	show_usage(argv[0]);
 	exit(EXIT_FAILURE);
     }
-    ret = do_crypt(stdin, stdout, key, iv, !!enc, padding);
+    ret = do_crypt(stdin, stdout, cipher, key, iv, !!enc, padding);
     if (ret)
 	fprintf(stderr, "Error during crypt operation.\n");
     OPENSSL_free(iv);