des: prevent error when using two key triple DES with a random key

Two key 3DES only sets two keys and the random generation errors out if fewer than three keys are required. It shouldn't. Fixes openssl#20212 Reviewed-by: Tomas Mraz <[email protected]> Reviewed-by: Matt Caswell <[email protected]> (Merged from openssl#20224)
starrify · Feb 8, 2023 · 587e040 · 587e040
1 parent ae08ed0
commit 587e040
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Showing 2 changed files with 28 additions and 5 deletions.
diff --git a/providers/implementations/ciphers/cipher_tdes_common.c b/providers/implementations/ciphers/cipher_tdes_common.c
@@ -121,13 +121,12 @@ static int tdes_generatekey(PROV_CIPHER_CTX *ctx, void *ptr)
     if (kl == 0 || RAND_priv_bytes_ex(ctx->libctx, ptr, kl, 0) <= 0)
         return 0;
     DES_set_odd_parity(deskey);
-    if (kl >= 16)
+    if (kl >= 16) {
         DES_set_odd_parity(deskey + 1);
-    if (kl >= 24) {
-        DES_set_odd_parity(deskey + 2);
-        return 1;
+        if (kl >= 24)
+            DES_set_odd_parity(deskey + 2);
     }
-    return 0;
+    return 1;
 }
 
 int ossl_tdes_get_ctx_params(void *vctx, OSSL_PARAM params[])

diff --git a/test/destest.c b/test/destest.c
@@ -838,6 +838,29 @@ static int test_des_check_bad_parity(int n)
 
     return TEST_int_eq(DES_check_key_parity(key), bad_parity_keys[n].expect);
 }
+
+/* Test that two key 3DES can generate a random key without error */
+static int test_des_two_key(void)
+{
+    int res = 0;
+    EVP_CIPHER *cipher = NULL;
+    EVP_CIPHER_CTX *ctx = NULL;
+    unsigned char key[16];
+
+    if (!TEST_ptr(cipher = EVP_CIPHER_fetch(NULL, "DES-EDE-ECB", NULL))
+            || !TEST_ptr(ctx = EVP_CIPHER_CTX_new())
+            || !EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, 1)
+            || !EVP_CIPHER_CTX_set_key_length(ctx, sizeof(key))
+            || !EVP_CIPHER_CTX_rand_key(ctx, key))
+        goto err;
+
+    res = 1;
+ err:
+    EVP_CIPHER_free(cipher);
+    EVP_CIPHER_CTX_free(ctx);
+    return res;
+}
+
 #endif
 
 int setup_tests(void)
@@ -866,6 +889,7 @@ int setup_tests(void)
     ADD_ALL_TESTS(test_des_key_wrap, OSSL_NELEM(test_des_key_wrap_sizes));
     ADD_ALL_TESTS(test_des_weak_keys, OSSL_NELEM(weak_keys));
     ADD_ALL_TESTS(test_des_check_bad_parity, OSSL_NELEM(bad_parity_keys));
+    ADD_TEST(test_des_two_key);
 #endif
     return 1;
 }