diff --git a/scripts/patchsqlite3.sh b/scripts/patchsqlite3.sh
index 3062548..5a689f5 100644
--- a/scripts/patchsqlite3.sh
+++ b/scripts/patchsqlite3.sh
@@ -17,7 +17,7 @@ die() {
 # 1) Intercept VFS pragma handling
 # 2) Add handling of KEY parameter in ATTACH statements
 sed 's/sqlite3_file_control\(.*SQLITE_FCNTL_PRAGMA\)/sqlite3mcFileControlPragma\1/' "$INPUT" \
-    | sed '/\#endif \/\* SQLITE3\_H \*\//a \ \n\/\* Function prototypes of SQLite3 Multiple Ciphers \*\/\nSQLITE_PRIVATE int sqlite3mcCheckVfs(const char*);\nSQLITE_PRIVATE int sqlite3mcFileControlPragma(sqlite3*, const char*, int, void*);\nSQLITE_PRIVATE int sqlite3mcHandleAttachKey(sqlite3*, const char*, const char*, sqlite3_value*, char**);\nSQLITE_PRIVATE int sqlite3mcHandleMainKey(sqlite3*, const char*);\ntypedef struct PgHdr PgHdrMC;\nSQLITE_PRIVATE void* sqlite3mcPagerCodec(PgHdrMC* pPg);\ntypedef struct Pager PagerMC;\nSQLITE_PRIVATE int sqlite3mcPagerHasCodec(PagerMC* pPager);\nSQLITE_PRIVATE void sqlite3mcInitMemoryMethods();' \
+    | sed '/\#endif \/\* SQLITE3\_H \*\//a \ \n\/\* Function prototypes of SQLite3 Multiple Ciphers \*\/\nSQLITE_PRIVATE int sqlite3mcCheckVfs(const char*);\nSQLITE_PRIVATE int sqlite3mcFileControlPragma(sqlite3*, const char*, int, void*);\nSQLITE_PRIVATE int sqlite3mcHandleAttachKey(sqlite3*, const char*, const char*, sqlite3_value*, char**);\nSQLITE_PRIVATE int sqlite3mcHandleMainKey(sqlite3*, const char*);\ntypedef struct PgHdr PgHdrMC;\nSQLITE_PRIVATE void* sqlite3mcPagerCodec(PgHdrMC* pPg);\ntypedef struct Pager PagerMC;\nSQLITE_PRIVATE int sqlite3mcPagerHasCodec(PagerMC* pPager);\nSQLITE_PRIVATE void sqlite3mcInitMemoryMethods();\nSQLITE_PRIVATE int sqlite3mcIsBackupSupported(sqlite3*, const char*, sqlite3*, const char*);' \
     | sed '/\#define MAX\_PATHNAME 512/c #if SQLITE3MC\_MAX\_PATHNAME \> 512\n#define MAX_PATHNAME SQLITE3MC\_MAX\_PATHNAME\n#else\n#define MAX_PATHNAME 512\n#endif' \
     | sed '/pData = pPage->pData;/c \  if( (pData = sqlite3mcPagerCodec(pPage))==0 ) return SQLITE_NOMEM_BKPT;' \
     | sed '/pData = p->pData;/c \        if( (pData = sqlite3mcPagerCodec(p))==0 ) return SQLITE_NOMEM;' \
@@ -26,4 +26,5 @@ sed 's/sqlite3_file_control\(.*SQLITE_FCNTL_PRAGMA\)/sqlite3mcFileControlPragma\
     | sed '/sqlite3_free_filename(zOpen);/i \\n  \/\* Handle encryption related URI parameters. \*\/\n  if( rc==SQLITE_OK ){\n    rc = sqlite3mcHandleMainKey(db, zOpen);\n  }' \
     | sed '/^  if( sqlite3PCacheIsDirty(pPager->pPCache) ) return 0;/a \  if( sqlite3mcPagerHasCodec(pPager) != 0 ) return 0;' \
     | sed '/^  }else if( USEFETCH(pPager) ){/c \  }else if( USEFETCH(pPager) && sqlite3mcPagerHasCodec(pPager) == 0 ){' \
-    | sed '/^  if( rc!=SQLITE_OK ) memset(&mem0, 0, sizeof(mem0));/a \\n  \/\* Initialize wrapper for memory management.\*\/\n  if( rc==SQLITE_OK ) {\n    sqlite3mcInitMemoryMethods();\n  }\n'
+    | sed '/^  if( rc!=SQLITE_OK ) memset(&mem0, 0, sizeof(mem0));/a \\n  \/\* Initialize wrapper for memory management.\*\/\n  if( rc==SQLITE_OK ) {\n    sqlite3mcInitMemoryMethods();\n  }\n' \
+    | sed '/Lock the source database handle./i \  \/\* Check whether databases are compatible with backup \*\/\n  if (!sqlite3mcIsBackupSupported(pSrcDb, zSrcDb, pDestDb, zDestDb)){\n    sqlite3ErrorWithMsg(pDestDb, SQLITE_ERROR, \"backup is not supported with incompatible source and target databases\");\n    return NULL;\n  }\n'
diff --git a/src/ascon/aead.c b/src/ascon/aead.c
index 1d9132e..a92fc45 100644
--- a/src/ascon/aead.c
+++ b/src/ascon/aead.c
@@ -88,7 +88,7 @@ forceinline void ascon_adata(ascon_state_t* s, const uint8_t* ad,
     ASCON_P(s, nr);
   }
   /* domain separation */
-  s->x[4] ^= 1;
+  s->x[4] ^= ASCON_DSEP();
   ascon_printstate("domain separation", s);
 }
 
diff --git a/src/ascon/word.h b/src/ascon/word.h
index cfd960a..972b55d 100644
--- a/src/ascon/word.h
+++ b/src/ascon/word.h
@@ -15,6 +15,8 @@ typedef union {
 
 #define ASCON_U64TOWORD(x) ASCON_U64BIG(x)
 #define ASCON_WORDTOU64(x) ASCON_U64BIG(x)
+#define ASCON_LOAD(b, n) ASCON_LOADBYTES(b, n)
+#define ASCON_STORE(b, w, n) ASCON_STOREBYTES(b, w, n)
 
 forceinline uint64_t ASCON_ROR(uint64_t x, int n) { return x >> n | x << (-n & 63); }
 
@@ -32,6 +34,8 @@ forceinline int ASCON_NOTZERO(uint64_t a, uint64_t b) {
 
 forceinline uint64_t ASCON_PAD(int i) { return 0x80ull << (56 - 8 * i); }
 
+forceinline uint64_t ASCON_DSEP() { return 0x01; }
+
 forceinline uint64_t ASCON_PRFS_MLEN(uint64_t len) { return len << 51; }
 
 forceinline uint64_t ASCON_CLEAR(uint64_t w, int n) {
@@ -45,16 +49,6 @@ forceinline uint64_t ASCON_MASK(int n) {
   return ~0ull >> (64 - 8 * n);
 }
 
-forceinline uint64_t ASCON_LOAD(const uint8_t* bytes, int n) {
-  uint64_t x = *(uint64_t*)bytes & ASCON_MASK(n);
-  return ASCON_U64TOWORD(x);
-}
-
-forceinline void ASCON_STORE(uint8_t* bytes, uint64_t w, int n) {
-  *(uint64_t*)bytes &= ~ASCON_MASK(n);
-  *(uint64_t*)bytes |= ASCON_WORDTOU64(w);
-}
-
 forceinline uint64_t ASCON_LOADBYTES(const uint8_t* bytes, int n) {
   uint64_t x = 0;
   memcpy(&x, bytes, n);
diff --git a/src/cipher_sqlcipher.c b/src/cipher_sqlcipher.c
index e97467f..0e7b2bf 100644
--- a/src/cipher_sqlcipher.c
+++ b/src/cipher_sqlcipher.c
@@ -356,7 +356,7 @@ EncryptPageSQLCipherCipher(void* cipher, int page, unsigned char* data, int len,
   int n = len - nReserved;
   int offset = (page == 1) ? (sqlCipherCipher->m_legacy != 0) ? 16 : 24 : 0;
   int blen;
-  unsigned char iv[64];
+  unsigned char iv[128];
   int usePlaintextHeader = 0;
 
   /* Check whether a plaintext header should be used */
@@ -373,10 +373,10 @@ EncryptPageSQLCipherCipher(void* cipher, int page, unsigned char* data, int len,
   }
 
   /* Generate nonce (64 bytes) */
-  memset(iv, 0, 64);
+  memset(iv, 0, 128);
   if (nReserved > 0)
   {
-    chacha20_rng(iv, 64);
+    chacha20_rng(iv, 128);
   }
   else
   {
diff --git a/src/sqlite3mc_vfs.c b/src/sqlite3mc_vfs.c
index 0f1e4d5..c126af4 100644
--- a/src/sqlite3mc_vfs.c
+++ b/src/sqlite3mc_vfs.c
@@ -301,6 +301,29 @@ SQLITE_PRIVATE Codec* sqlite3mcGetMainCodec(sqlite3* db)
   return sqlite3mcGetCodec(db, "main");
 }
 
+SQLITE_PRIVATE int sqlite3mcIsBackupSupported(sqlite3* pSrc, const char* zSrc, sqlite3* pDest, const char* zDest)
+{
+  int ok = 1;
+  if (pSrc != pDest)
+  {
+    Codec* codecSrc = sqlite3mcGetCodec(pSrc, zSrc);
+    Codec* codecDest = sqlite3mcGetCodec(pDest, zDest);
+    if (codecSrc && codecDest)
+    {
+      /* Both databases have a codec */
+      ok = sqlite3mcIsEncrypted(codecSrc) && sqlite3mcIsEncrypted(codecDest) &&
+           (sqlite3mcGetReadReserved(codecSrc) == sqlite3mcGetWriteReserved(codecDest));
+    }
+    else
+    {
+      /* At least one database has no codec */
+      /* Backup supported if both databases are plain databases */
+      ok = !codecSrc && !codecDest;
+    }
+  }
+  return ok;
+}
+
 /*
 ** Set the codec of the database file with the given database file name.
 **
diff --git a/src/sqlite3patched.c b/src/sqlite3patched.c
index dd361c1..3acf59b 100644
--- a/src/sqlite3patched.c
+++ b/src/sqlite3patched.c
@@ -11170,6 +11170,7 @@ SQLITE_PRIVATE void* sqlite3mcPagerCodec(PgHdrMC* pPg);
 typedef struct Pager PagerMC;
 SQLITE_PRIVATE int sqlite3mcPagerHasCodec(PagerMC* pPager);
 SQLITE_PRIVATE void sqlite3mcInitMemoryMethods();
+SQLITE_PRIVATE int sqlite3mcIsBackupSupported(sqlite3*, const char*, sqlite3*, const char*);
 
 /******** Begin file sqlite3rtree.h *********/
 /*
@@ -82186,6 +82187,12 @@ SQLITE_API sqlite3_backup *sqlite3_backup_init(
   }
 #endif
 
+  /* Check whether databases are compatible with backup */
+  if (!sqlite3mcIsBackupSupported(pSrcDb, zSrcDb, pDestDb, zDestDb)){
+    sqlite3ErrorWithMsg(pDestDb, SQLITE_ERROR, "backup is not supported with incompatible source and target databases");
+    return NULL;
+  }
+
   /* Lock the source database handle. The destination database
   ** handle is not locked in this routine, but it is locked in
   ** sqlite3_backup_step(). The user is required to ensure that no