pragmas to override hmac salt mask and allow migration of 2.0 beta databases

sjlombardo · sjlombardo · commit caf3865b8baa · 2012-11-16T11:13:14.000-05:00
diff --git a/sqlcipher-2.0-beta-testkey.db b/sqlcipher-2.0-beta-testkey.db
diff --git a/src/crypto.c b/src/crypto.c
@@ -163,6 +163,16 @@ int codec_pragma(sqlite3* db, int iDb, Parse *pParse, const char *zLeft, const c
       sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_LE_PGNO);
       sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_BE_PGNO);
     }
+  }else
+  if( sqlite3StrICmp(zLeft,"cipher_hmac_salt_mask")==0 ){
+    if(zRight) {
+      if (sqlite3StrNICmp(zRight ,"x'", 2) == 0 && sqlite3Strlen30(zRight) == 5) {
+        unsigned char mask = 0;
+        const char *hex = zRight+2;
+        cipher_hex2bin(hex,2,&mask);
+        sqlcipher_set_hmac_salt_mask(mask);
+      }
+    }
   }else {
     return 0;
   }
diff --git a/src/crypto.h b/src/crypto.h
@@ -177,6 +177,7 @@ void* sqlcipher_codec_ctx_get_data(codec_ctx *);
 void sqlcipher_exportFunc(sqlite3_context *, int, sqlite3_value **);
 
 void sqlcipher_set_default_use_hmac(int use);
+void sqlcipher_set_hmac_salt_mask(unsigned char mask);
 
 int sqlcipher_codec_ctx_set_use_hmac(codec_ctx *ctx, int use);
 
diff --git a/src/crypto_impl.c b/src/crypto_impl.c
@@ -80,6 +80,7 @@ int sqlcipher_cipher_ctx_key_derive(codec_ctx *, cipher_ctx *);
 int sqlcipher_page_hmac(cipher_ctx *, Pgno, unsigned char *, int, unsigned char *);
 
 static unsigned int default_flags = DEFAULT_CIPHER_FLAGS;
+static unsigned char hmac_salt_mask = HMAC_SALT_MASK;
 
 static unsigned int openssl_external_init = 0;
 static unsigned int openssl_init_count = 0;
@@ -397,6 +398,10 @@ void sqlcipher_set_default_use_hmac(int use) {
   else default_flags &= ~CIPHER_FLAG_HMAC; 
 }
 
+void sqlcipher_set_hmac_salt_mask(unsigned char mask) {
+  hmac_salt_mask = mask;
+}
+
 int sqlcipher_get_default_use_hmac(Parse *pParse) {
   int default_use_hmac_set = default_flags & CIPHER_FLAG_HMAC > 0;
   char *default_use_hmac = sqlite3_mprintf("%d", default_use_hmac_set);
@@ -749,7 +754,7 @@ int sqlcipher_cipher_ctx_key_derive(codec_ctx *ctx, cipher_ctx *c_ctx) {
          to generate the encryption key */ 
       memcpy(ctx->hmac_kdf_salt, ctx->kdf_salt, ctx->kdf_salt_sz);
       for(i = 0; i < ctx->kdf_salt_sz; i++) {
-        ctx->hmac_kdf_salt[i] ^= HMAC_SALT_MASK;
+        ctx->hmac_kdf_salt[i] ^= hmac_salt_mask;
       } 
 
       CODEC_TRACE(("codec_key_derive: deriving hmac key from encryption key using PBKDF2 with %d iterations\n", 
diff --git a/test/crypto.test b/test/crypto.test
@@ -1649,6 +1649,10 @@ do_test verify-pragma-cipher-default-use-hmac-off {
     execsql {
         PRAGMA cipher_default_use_hmac = off;
         PRAGMA cipher_default_use_hmac;
+        -- Be sure to turn cipher_default_use_hmac
+        -- back on or it will break later tests 
+        -- (it's a global flag)
+        PRAGMA cipher_default_use_hmac = ON;
     }
 } {0}
 db close
@@ -1729,4 +1733,50 @@ do_test verify-pragma-cipher-changed {
 db close
 file delete -force test.db
 
+# open a 2.0 beta database with 4000 round hmac kdf and 0x00 
+# hmac salt mask 
+# verify it can be opened
+do_test open-2.0-beta-database {
+  sqlite_orig db sqlcipher-2.0-beta-testkey.db
+  execsql {
+    PRAGMA key = 'testkey';
+    PRAGMA fast_kdf_iter = 4000;
+    PRAGMA cipher_hmac_salt_mask = "x'00'";
+    SELECT count(*) FROM t1;
+    SELECT * FROM t1;
+  } 
+} {2 test-0-0 test-0-1 test-1-0 test-1-1}
+db close
+
+# open a 2.0 beta database 
+# attach a new standard database
+# copy schema between the two, and verify the latter 
+# can be opened
+do_test 2.0-beta-to-2.0-migration {
+  sqlite_orig db sqlcipher-2.0-beta-testkey.db
+
+  execsql {
+    PRAGMA key = 'testkey';
+    PRAGMA cipher_hmac_salt_mask = "x'00'";
+    PRAGMA fast_kdf_iter = 4000;
+    SELECT count(*) FROM sqlite_master;
+
+    PRAGMA cipher_hmac_salt_mask = "x'3a'";
+    ATTACH DATABASE 'test.db' AS db2 KEY 'testkey'; 
+    
+    CREATE TABLE db2.t1(a,b);
+    INSERT INTO db2.t1 SELECT * FROM main.t1;
+    DETACH DATABASE db2;
+  }
+  db close
+
+  sqlite_orig db test.db
+  execsql {
+    PRAGMA key = 'testkey';
+    SELECT * FROM t1;
+  }
+} {test-0-0 test-0-1 test-1-0 test-1-1}
+db close
+file delete -force test.db
+
 finish_test
