From 8f061f1a50b643aae195a85765deb77ff855416b Mon Sep 17 00:00:00 2001
From: Stephen Lombardo <sjlombardo@zetetic.net>
Date: Wed, 29 Feb 2012 11:14:42 -0500
Subject: [PATCH] add pragma cipher_default_use_hmac to toggle global HMAC
 setting

---
 src/crypto.c      |  4 ++++
 src/crypto.h      |  2 ++
 src/crypto_impl.c |  9 ++++++-
 src/pragma.c      | 10 ++++----
 test/crypto.test  | 60 +++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 79 insertions(+), 6 deletions(-)

diff --git a/src/crypto.c b/src/crypto.c
index 5c8b2d6..431613e 100644
--- a/src/crypto.c
+++ b/src/crypto.c
@@ -77,6 +77,10 @@ static int codec_set_btree_to_codec_pagesize(sqlite3 *db, Db *pDb, codec_ctx *ct
   return rc;
 }
 
+void codec_set_default_use_hmac(int use) {
+  sqlcipher_set_default_use_hmac(use);
+}
+
 int codec_set_use_hmac(sqlite3* db, int nDb, int use) {
   struct Db *pDb = &db->aDb[nDb];
 
diff --git a/src/crypto.h b/src/crypto.h
index a5a62ec..7a7165b 100644
--- a/src/crypto.h
+++ b/src/crypto.h
@@ -149,6 +149,8 @@ void* sqlcipher_codec_ctx_get_data(codec_ctx *);
 
 void sqlcipher_exportFunc(sqlite3_context *, int, sqlite3_value **);
 
+void sqlcipher_set_default_use_hmac(int use);
+
 int sqlcipher_codec_ctx_set_use_hmac(codec_ctx *ctx, int use);
 /* end extensions defined in crypto_impl.c */
 
diff --git a/src/crypto_impl.c b/src/crypto_impl.c
index 336afbd..f0e9dfb 100644
--- a/src/crypto_impl.c
+++ b/src/crypto_impl.c
@@ -79,6 +79,8 @@ int sqlcipher_cipher_ctx_key_derive(codec_ctx *, cipher_ctx *);
 /* prototype for pager HMAC function */
 int sqlcipher_page_hmac(cipher_ctx *, Pgno, unsigned char *, int, unsigned char *);
 
+static int default_use_hmac = DEFAULT_USE_HMAC;
+
 struct codec_ctx {
   int kdf_salt_sz;
   int page_sz;
@@ -325,7 +327,12 @@ int sqlcipher_codec_ctx_set_fast_kdf_iter(codec_ctx *ctx, int fast_kdf_iter, int
   return SQLITE_OK;
 }
 
+/* set the global default flag for HMAC */
+void sqlcipher_set_default_use_hmac(int use) {
+  default_use_hmac = use;
+}
 
+/* set the codec flag for whether this individual database should be using hmac */
 int sqlcipher_codec_ctx_set_use_hmac(codec_ctx *ctx, int use) {
   int reserve = EVP_MAX_IV_LENGTH; /* base reserve size will be IV only */ 
 
@@ -432,7 +439,7 @@ int sqlcipher_codec_ctx_init(codec_ctx **iCtx, Db *pDb, Pager *pPager, sqlite3_f
 
   /* Use HMAC signatures by default. Note that codec_set_use_hmac will implicity call
      codec_set_page_size to set the default */
-  if((rc = sqlcipher_codec_ctx_set_use_hmac(ctx, DEFAULT_USE_HMAC)) != SQLITE_OK) return rc;
+  if((rc = sqlcipher_codec_ctx_set_use_hmac(ctx, default_use_hmac)) != SQLITE_OK) return rc;
 
   if((rc = sqlcipher_cipher_ctx_copy(ctx->write_ctx, ctx->read_ctx)) != SQLITE_OK) return rc;
 
diff --git a/src/pragma.c b/src/pragma.c
index d9047e1..264c133 100644
--- a/src/pragma.c
+++ b/src/pragma.c
@@ -1515,13 +1515,13 @@ void sqlite3Pragma(
     extern int codec_set_page_size(sqlite3*, int, int); 
     codec_set_page_size(db, iDb, atoi(zRight)); // change page size
   }else
+  if( sqlite3StrICmp(zLeft,"cipher_default_use_hmac")==0 ){
+    extern void codec_set_default_use_hmac(int);
+    codec_set_default_use_hmac(sqlite3GetBoolean(zRight));
+  }else
   if( sqlite3StrICmp(zLeft,"cipher_use_hmac")==0 ){
     extern int codec_set_use_hmac(sqlite3*, int, int);
-    if(sqlite3GetBoolean(zRight)) {
-      codec_set_use_hmac(db, iDb, 1);
-    } else {
-      codec_set_use_hmac(db, iDb, 0);
-    }
+    codec_set_use_hmac(db, iDb, sqlite3GetBoolean(zRight));
   }else
 /** END CRYPTO **/
 #endif
diff --git a/test/crypto.test b/test/crypto.test
index aabb481..7824056 100644
--- a/test/crypto.test
+++ b/test/crypto.test
@@ -1145,4 +1145,64 @@ do_test cipher-options-before-keys {
 db close
 file delete -force test.db
 
+# open a 1.1.8 database (no HMAC), then 
+# try to open another 1.1.8 database. The
+# attached database should have the same hmac
+# setting as the original 
+do_test default-use-hmac-attach {
+  file copy -force sqlcipher-1.1.8-testkey.db test.db
+  sqlite_orig db test.db
+  execsql {
+    PRAGMA cipher_default_use_hmac = OFF;
+    PRAGMA key = 'testkey';
+    SELECT count(*) FROM t1;
+    ATTACH 'sqlcipher-1.1.8-testkey.db' AS db2;
+    SELECT count(*) from db2.t1;
+    PRAGMA cipher_default_use_hmac = ON;
+  } 
+} {4 4}
+db close
+file delete -force test.db
+
+# open a 2.0 database (with HMAC), then 
+# try to a 1.1.8 database. this should 
+# fail because the hmac setting for the 
+# attached database is not compatible
+do_test attach-1.1.8-database-from-2.0-fails {
+  sqlite_orig db test.db
+  catchsql {
+    PRAGMA key = 'testkey';
+    CREATE table t1(a,b);
+    ATTACH 'sqlcipher-1.1.8-testkey.db' AS db2;
+  } 
+} {1 {file is encrypted or is not a database}}
+db close
+file delete -force test.db
+
+# open a 2.0 database (with HMAC), then 
+# set the default hmac setting to OFF.
+# try to a 1.1.8 database. this should 
+# succeed now that hmac is off by default
+# before the attach
+do_test change-default-use-hmac-attach {
+  sqlite_orig db test.db
+  execsql {
+    PRAGMA key = 'testkey';
+    CREATE table t1(a,b);
+    INSERT INTO t1(a,b) VALUES (1,2);
+  }
+  db close
+  sqlite_orig db test.db
+  execsql {
+    PRAGMA key = 'testkey';
+    SELECT count(*) FROM t1;
+    PRAGMA cipher_default_use_hmac = OFF;
+    ATTACH 'sqlcipher-1.1.8-testkey.db' AS db2;
+    SELECT count(*) from db2.t1;
+    PRAGMA cipher_default_use_hmac = ON;
+  } 
+} {1 4}
+db close
+file delete -force test.db
+
 finish_test