/* 
** SQLCipher
** http://sqlcipher.net
** 
** Copyright (c) 2008 - 2013, ZETETIC LLC
** All rights reserved.
** 
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are met:
**     * Redistributions of source code must retain the above copyright
**       notice, this list of conditions and the following disclaimer.
**     * Redistributions in binary form must reproduce the above copyright
**       notice, this list of conditions and the following disclaimer in the
**       documentation and/or other materials provided with the distribution.
**     * Neither the name of the ZETETIC LLC nor the
**       names of its contributors may be used to endorse or promote products
**       derived from this software without specific prior written permission.
** 
** THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY
** EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
** DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY
** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**  
*/
/* BEGIN SQLCIPHER */
#ifdef SQLITE_HAS_CODEC

#include <assert.h>
#include "sqlcipher.h"
#include "crypto.h"

#ifdef SQLCIPHER_LICENSE
#include "sqlcipher-license.h"
#endif

/* Generate code to return a string value */
static void codec_vdbe_return_string(Parse *pParse, const char *zLabel, const char *value, int value_type){
  Vdbe *v = sqlite3GetVdbe(pParse);
  sqlite3VdbeSetNumCols(v, 1);
  sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zLabel, SQLITE_STATIC);
  sqlite3VdbeAddOp4(v, OP_String8, 0, 1, 0, value, value_type);
  sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 1);
}

static int codec_set_btree_to_codec_pagesize(sqlite3 *db, Db *pDb, codec_ctx *ctx) {
  int rc, page_sz, reserve_sz; 

  page_sz = sqlcipher_codec_ctx_get_pagesize(ctx);
  reserve_sz = sqlcipher_codec_ctx_get_reservesize(ctx);

  CODEC_TRACE("codec_set_btree_to_codec_pagesize: sqlite3BtreeSetPageSize() size=%d reserve=%d\n", page_sz, reserve_sz);

  CODEC_TRACE_MUTEX("codec_set_btree_to_codec_pagesize: entering database mutex %p\n", db->mutex);
  sqlite3_mutex_enter(db->mutex);
  CODEC_TRACE_MUTEX("codec_set_btree_to_codec_pagesize: entered database mutex %p\n", db->mutex);
  db->nextPagesize = page_sz; 

  /* before forcing the page size we need to unset the BTS_PAGESIZE_FIXED flag, else  
     sqliteBtreeSetPageSize will block the change  */
  pDb->pBt->pBt->btsFlags &= ~BTS_PAGESIZE_FIXED;
  rc = sqlite3BtreeSetPageSize(pDb->pBt, page_sz, reserve_sz, 0);

  CODEC_TRACE("codec_set_btree_to_codec_pagesize: sqlite3BtreeSetPageSize returned %d\n", rc);

  CODEC_TRACE_MUTEX("codec_set_btree_to_codec_pagesize: leaving database mutex %p\n", db->mutex);
  sqlite3_mutex_leave(db->mutex);
  CODEC_TRACE_MUTEX("codec_set_btree_to_codec_pagesize: left database mutex %p\n", db->mutex);

  return rc;
}

static int codec_set_pass_key(sqlite3* db, int nDb, const void *zKey, int nKey, int for_ctx) {
  struct Db *pDb = &db->aDb[nDb];
  CODEC_TRACE("codec_set_pass_key: entered db=%p nDb=%d zKey=%s nKey=%d for_ctx=%d\n", db, nDb, (char *)zKey, nKey, for_ctx);
  if(pDb->pBt) {
    codec_ctx *ctx = (codec_ctx*) sqlite3PagerGetCodec(pDb->pBt->pBt->pPager);

    if(ctx) return sqlcipher_codec_ctx_set_pass(ctx, zKey, nKey, for_ctx);
  }
  return SQLITE_ERROR;
} 

int sqlcipher_codec_pragma(sqlite3* db, int iDb, Parse *pParse, const char *zLeft, const char *zRight) {
  struct Db *pDb = &db->aDb[iDb];
  codec_ctx *ctx = NULL;
  int rc;

  if(pDb->pBt) {
    ctx = (codec_ctx*) sqlite3PagerGetCodec(pDb->pBt->pBt->pPager);
  }

  CODEC_TRACE("sqlcipher_codec_pragma: entered db=%p iDb=%d pParse=%p zLeft=%s zRight=%s ctx=%p\n", db, iDb, pParse, zLeft, zRight, ctx);
  
#ifdef SQLCIPHER_LICENSE
  if( sqlite3StrICmp(zLeft, "cipher_license")==0 && zRight ){
    char *license_result = sqlite3_mprintf("%d", sqlcipher_license_key(zRight));
    codec_vdbe_return_string(pParse, "cipher_license", license_result, P4_DYNAMIC);
  } else
    if( sqlite3StrICmp(zLeft, "cipher_license")==0 && !zRight ){
      if(ctx) {
        char *license_result = sqlite3_mprintf("%d", ctx
                                               ? sqlcipher_license_key_status(ctx)
                                               : SQLITE_ERROR);
        codec_vdbe_return_string(pParse, "cipher_license", license_result, P4_DYNAMIC);
      }
  } else
#endif
  if( sqlite3StrICmp(zLeft, "cipher_fips_status")== 0 && !zRight ){
    if(ctx) {
      char *fips_mode_status = sqlite3_mprintf("%d", sqlcipher_codec_fips_status(ctx));
      codec_vdbe_return_string(pParse, "cipher_fips_status", fips_mode_status, P4_DYNAMIC);
    }
  } else
  if( sqlite3StrICmp(zLeft, "cipher_store_pass")==0 && zRight ) {
    if(ctx) {
      sqlcipher_codec_set_store_pass(ctx, sqlite3GetBoolean(zRight, 1));
    }
  } else
  if( sqlite3StrICmp(zLeft, "cipher_store_pass")==0 && !zRight ) {
    if(ctx){
      char *store_pass_value = sqlite3_mprintf("%d", sqlcipher_codec_get_store_pass(ctx));
      codec_vdbe_return_string(pParse, "cipher_store_pass", store_pass_value, P4_DYNAMIC);
    }
  } else
  if( sqlite3StrICmp(zLeft, "cipher_add_random")==0 && zRight ){
    if(ctx) {
      char *add_random_status = sqlite3_mprintf("%d", sqlcipher_codec_add_random(ctx, zRight, sqlite3Strlen30(zRight)));
      codec_vdbe_return_string(pParse, "cipher_add_random", add_random_status, P4_DYNAMIC);
    }
  } else
  if( sqlite3StrICmp(zLeft, "cipher_migrate")==0 && !zRight ){
    if(ctx){
      char *migrate_status = sqlite3_mprintf("%d", sqlcipher_codec_ctx_migrate(ctx));
      codec_vdbe_return_string(pParse, "cipher_migrate", migrate_status, P4_DYNAMIC);
    }
  } else
  if( sqlite3StrICmp(zLeft, "cipher_provider")==0 && !zRight ){
    if(ctx) { codec_vdbe_return_string(pParse, "cipher_provider",
                                              sqlcipher_codec_get_cipher_provider(ctx), P4_TRANSIENT);
    }
  } else
  if( sqlite3StrICmp(zLeft, "cipher_provider_version")==0 && !zRight){
    if(ctx) { codec_vdbe_return_string(pParse, "cipher_provider_version",
                                              sqlcipher_codec_get_provider_version(ctx), P4_TRANSIENT);
    }
  } else
  if( sqlite3StrICmp(zLeft, "cipher_version")==0 && !zRight ){
#ifdef CIPHER_VERSION_QUALIFIER
    char *version = sqlite3_mprintf("%s %s %s", CIPHER_XSTR(CIPHER_VERSION_NUMBER), CIPHER_XSTR(CIPHER_VERSION_QUALIFIER), CIPHER_XSTR(CIPHER_VERSION_BUILD));
#else
    char *version = sqlite3_mprintf("%s %s", CIPHER_XSTR(CIPHER_VERSION_NUMBER), CIPHER_XSTR(CIPHER_VERSION_BUILD));
#endif
    codec_vdbe_return_string(pParse, "cipher_version", version, P4_DYNAMIC);
  } else
  if( sqlite3StrICmp(zLeft, "cipher")==0 ){
    if(ctx) {
      if( zRight ) {
        const char* message = "PRAGMA cipher is no longer supported.";
        codec_vdbe_return_string(pParse, "cipher", message, P4_TRANSIENT);
        sqlite3_log(SQLITE_WARNING, message);
      }else {
        codec_vdbe_return_string(pParse, "cipher", sqlcipher_codec_ctx_get_cipher(ctx), P4_TRANSIENT); 
      }
    }
  } else
  if( sqlite3StrICmp(zLeft, "rekey_cipher")==0 && zRight ){
    const char* message = "PRAGMA rekey_cipher is no longer supported.";
    codec_vdbe_return_string(pParse, "rekey_cipher", message, P4_TRANSIENT);
    sqlite3_log(SQLITE_WARNING, message);
  } else
  if( sqlite3StrICmp(zLeft,"cipher_default_kdf_iter")==0 ){
    if( zRight ) {
      sqlcipher_set_default_kdf_iter(atoi(zRight)); /* change default KDF iterations */
    } else {
      char *kdf_iter = sqlite3_mprintf("%d", sqlcipher_get_default_kdf_iter());
      codec_vdbe_return_string(pParse, "cipher_default_kdf_iter", kdf_iter, P4_DYNAMIC);
    }
  }else
  if( sqlite3StrICmp(zLeft, "kdf_iter")==0 ){
    if(ctx) {
      if( zRight ) {
        sqlcipher_codec_ctx_set_kdf_iter(ctx, atoi(zRight)); /* change of RW PBKDF2 iteration */
      } else {
        char *kdf_iter = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_kdf_iter(ctx));
        codec_vdbe_return_string(pParse, "kdf_iter", kdf_iter, P4_DYNAMIC);
      }
    }
  }else
  if( sqlite3StrICmp(zLeft, "fast_kdf_iter")==0){
    if(ctx) {
      if( zRight ) {
        char *deprecation = "PRAGMA fast_kdf_iter is deprecated, please remove from use";
        sqlcipher_codec_ctx_set_fast_kdf_iter(ctx, atoi(zRight)); /* change of RW PBKDF2 iteration */
        codec_vdbe_return_string(pParse, "fast_kdf_iter", deprecation, P4_TRANSIENT);
        sqlite3_log(SQLITE_WARNING, deprecation);
      } else {
        char *fast_kdf_iter = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_fast_kdf_iter(ctx));
        codec_vdbe_return_string(pParse, "fast_kdf_iter", fast_kdf_iter, P4_DYNAMIC);
      }
    }
  }else
  if( sqlite3StrICmp(zLeft, "rekey_kdf_iter")==0 && zRight ){
    const char* message = "PRAGMA rekey_kdf_iter is no longer supported.";
    codec_vdbe_return_string(pParse, "rekey_kdf_iter", message, P4_TRANSIENT);
    sqlite3_log(SQLITE_WARNING, message);
  }else
  if( sqlite3StrICmp(zLeft,"cipher_page_size")==0 ){
    if(ctx) {
      if( zRight ) {
        int size = atoi(zRight);
        rc = sqlcipher_codec_ctx_set_pagesize(ctx, size);
        if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
        rc = codec_set_btree_to_codec_pagesize(db, pDb, ctx);
        if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
      } else {
        char * page_size = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_pagesize(ctx));
        codec_vdbe_return_string(pParse, "cipher_page_size", page_size, P4_DYNAMIC);
      }
    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_default_page_size")==0 ){
    if( zRight ) {
      sqlcipher_set_default_pagesize(atoi(zRight));
    } else {
      char *default_page_size = sqlite3_mprintf("%d", sqlcipher_get_default_pagesize());
      codec_vdbe_return_string(pParse, "cipher_default_page_size", default_page_size, P4_DYNAMIC);
    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_default_use_hmac")==0 ){
    if( zRight ) {
      sqlcipher_set_default_use_hmac(sqlite3GetBoolean(zRight,1));
    } else {
      char *default_use_hmac = sqlite3_mprintf("%d", sqlcipher_get_default_use_hmac());
      codec_vdbe_return_string(pParse, "cipher_default_use_hmac", default_use_hmac, P4_DYNAMIC);
    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_use_hmac")==0 ){
    if(ctx) {
      if( zRight ) {
        rc = sqlcipher_codec_ctx_set_use_hmac(ctx, sqlite3GetBoolean(zRight,1));
        if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
        /* since the use of hmac has changed, the page size may also change */
        rc = codec_set_btree_to_codec_pagesize(db, pDb, ctx);
        if(rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, rc);
      } else {
        char *hmac_flag = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_use_hmac(ctx));
        codec_vdbe_return_string(pParse, "cipher_use_hmac", hmac_flag, P4_DYNAMIC);
      }
    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_hmac_pgno")==0 ){
    if(ctx) {
      if(zRight) {
        char *deprecation = "PRAGMA cipher_hmac_pgno is deprecated, please remove from use";
        /* clear both pgno endian flags */
        if(sqlite3StrICmp(zRight, "le") == 0) {
          sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_BE_PGNO);
          sqlcipher_codec_ctx_set_flag(ctx, CIPHER_FLAG_LE_PGNO);
        } else if(sqlite3StrICmp(zRight, "be") == 0) {
          sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_LE_PGNO);
          sqlcipher_codec_ctx_set_flag(ctx, CIPHER_FLAG_BE_PGNO);
        } else if(sqlite3StrICmp(zRight, "native") == 0) {
          sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_LE_PGNO);
          sqlcipher_codec_ctx_unset_flag(ctx, CIPHER_FLAG_BE_PGNO);
        }
        codec_vdbe_return_string(pParse, "cipher_hmac_pgno", deprecation, P4_TRANSIENT);
        sqlite3_log(SQLITE_WARNING, deprecation);
 
      } else {
        if(sqlcipher_codec_ctx_get_flag(ctx, CIPHER_FLAG_LE_PGNO)) {
          codec_vdbe_return_string(pParse, "cipher_hmac_pgno", "le", P4_TRANSIENT);
        } else if(sqlcipher_codec_ctx_get_flag(ctx, CIPHER_FLAG_BE_PGNO)) {
          codec_vdbe_return_string(pParse, "cipher_hmac_pgno", "be", P4_TRANSIENT);
        } else {
          codec_vdbe_return_string(pParse, "cipher_hmac_pgno", "native", P4_TRANSIENT);
        }
      }
    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_hmac_salt_mask")==0 ){
    if(ctx) {
      if(zRight) {
        char *deprecation = "PRAGMA cipher_hmac_salt_mask is deprecated, please remove from use";
        if (sqlite3StrNICmp(zRight ,"x'", 2) == 0 && sqlite3Strlen30(zRight) == 5) {
          unsigned char mask = 0;
          const unsigned char *hex = (const unsigned char *)zRight+2;
          cipher_hex2bin(hex,2,&mask);
          sqlcipher_set_hmac_salt_mask(mask);
        }
        codec_vdbe_return_string(pParse, "cipher_hmac_salt_mask", deprecation, P4_TRANSIENT);
        sqlite3_log(SQLITE_WARNING, deprecation);
      } else {
        char *hmac_salt_mask = sqlite3_mprintf("%02x", sqlcipher_get_hmac_salt_mask());
        codec_vdbe_return_string(pParse, "cipher_hmac_salt_mask", hmac_salt_mask, P4_DYNAMIC);
      }
    }
  }else 
  if( sqlite3StrICmp(zLeft,"cipher_plaintext_header_size")==0 ){
    if(ctx) {
      if( zRight ) {
        int size = atoi(zRight);
        if((rc = sqlcipher_codec_ctx_set_plaintext_header_size(ctx, size)) != SQLITE_OK)
          sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR); 
      } else {
        char *size = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_plaintext_header_size(ctx));
        codec_vdbe_return_string(pParse, "cipher_plaintext_header_size", size, P4_DYNAMIC);
      }
    }
  }else 
  if( sqlite3StrICmp(zLeft,"cipher_default_plaintext_header_size")==0 ){
    if( zRight ) {
      sqlcipher_set_default_plaintext_header_size(atoi(zRight));
    } else {
      char *size = sqlite3_mprintf("%d", sqlcipher_get_default_plaintext_header_size());
      codec_vdbe_return_string(pParse, "cipher_default_plaintext_header_size", size, P4_DYNAMIC);
      sqlite3_free(size);
    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_salt")==0 ){
    if(ctx) {
      if(zRight) {
        if (sqlite3StrNICmp(zRight ,"x'", 2) == 0 && sqlite3Strlen30(zRight) == (FILE_HEADER_SZ*2)+3) {
          unsigned char *salt = (unsigned char*) sqlite3_malloc(FILE_HEADER_SZ);
          const unsigned char *hex = (const unsigned char *)zRight+2;
          cipher_hex2bin(hex,FILE_HEADER_SZ*2,salt);
          sqlcipher_codec_ctx_set_kdf_salt(ctx, salt, FILE_HEADER_SZ);
          sqlite3_free(salt);
        }
      } else {
        void *salt;
        char *hexsalt = (char*) sqlite3_malloc((FILE_HEADER_SZ*2)+1);
        if((rc = sqlcipher_codec_ctx_get_kdf_salt(ctx, &salt)) == SQLITE_OK) {
          cipher_bin2hex(salt, FILE_HEADER_SZ, hexsalt);
          codec_vdbe_return_string(pParse, "cipher_salt", hexsalt, P4_DYNAMIC);
        } else {
          sqlite3_free(hexsalt);
          sqlcipher_codec_ctx_set_error(ctx, rc);
        }
      }
    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_hmac_algorithm")==0 ){
    if(ctx) {
      if(zRight) {
        rc = SQLITE_ERROR;
        if(sqlite3StrICmp(zRight, SQLCIPHER_HMAC_SHA1_LABEL) == 0) {
          rc = sqlcipher_codec_ctx_set_hmac_algorithm(ctx, SQLCIPHER_HMAC_SHA1);
        } else if(sqlite3StrICmp(zRight, SQLCIPHER_HMAC_SHA256_LABEL) == 0) {
          rc = sqlcipher_codec_ctx_set_hmac_algorithm(ctx, SQLCIPHER_HMAC_SHA256);
        } else if(sqlite3StrICmp(zRight, SQLCIPHER_HMAC_SHA512_LABEL) == 0) {
          rc = sqlcipher_codec_ctx_set_hmac_algorithm(ctx, SQLCIPHER_HMAC_SHA512);
        }
        if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
        rc = codec_set_btree_to_codec_pagesize(db, pDb, ctx);
        if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
      } else {
        int algorithm = sqlcipher_codec_ctx_get_hmac_algorithm(ctx);
        if(algorithm == SQLCIPHER_HMAC_SHA1) {
          codec_vdbe_return_string(pParse, "cipher_hmac_algorithm", SQLCIPHER_HMAC_SHA1_LABEL, P4_TRANSIENT);
        } else if(algorithm == SQLCIPHER_HMAC_SHA256) {
          codec_vdbe_return_string(pParse, "cipher_hmac_algorithm", SQLCIPHER_HMAC_SHA256_LABEL, P4_TRANSIENT);
        } else if(algorithm == SQLCIPHER_HMAC_SHA512) {
          codec_vdbe_return_string(pParse, "cipher_hmac_algorithm", SQLCIPHER_HMAC_SHA512_LABEL, P4_TRANSIENT);
        }
      }
    }
  }else 
  if( sqlite3StrICmp(zLeft,"cipher_default_hmac_algorithm")==0 ){
    if(zRight) {
      rc = SQLITE_ERROR;
      if(sqlite3StrICmp(zRight, SQLCIPHER_HMAC_SHA1_LABEL) == 0) {
        rc = sqlcipher_set_default_hmac_algorithm(SQLCIPHER_HMAC_SHA1);
      } else if(sqlite3StrICmp(zRight, SQLCIPHER_HMAC_SHA256_LABEL) == 0) {
        rc = sqlcipher_set_default_hmac_algorithm(SQLCIPHER_HMAC_SHA256);
      } else if(sqlite3StrICmp(zRight, SQLCIPHER_HMAC_SHA512_LABEL) == 0) {
        rc = sqlcipher_set_default_hmac_algorithm(SQLCIPHER_HMAC_SHA512);
      }
    } else {
      int algorithm = sqlcipher_get_default_hmac_algorithm();
      if(algorithm == SQLCIPHER_HMAC_SHA1) {
        codec_vdbe_return_string(pParse, "cipher_default_hmac_algorithm", SQLCIPHER_HMAC_SHA1_LABEL, P4_TRANSIENT);
      } else if(algorithm == SQLCIPHER_HMAC_SHA256) {
        codec_vdbe_return_string(pParse, "cipher_default_hmac_algorithm", SQLCIPHER_HMAC_SHA256_LABEL, P4_TRANSIENT);
      } else if(algorithm == SQLCIPHER_HMAC_SHA512) {
        codec_vdbe_return_string(pParse, "cipher_default_hmac_algorithm", SQLCIPHER_HMAC_SHA512_LABEL, P4_TRANSIENT);
      }
    }
  }else 
  if( sqlite3StrICmp(zLeft,"cipher_kdf_algorithm")==0 ){
    if(ctx) {
      if(zRight) {
        rc = SQLITE_ERROR;
        if(sqlite3StrICmp(zRight, SQLCIPHER_PBKDF2_HMAC_SHA1_LABEL) == 0) {
          rc = sqlcipher_codec_ctx_set_kdf_algorithm(ctx, SQLCIPHER_PBKDF2_HMAC_SHA1);
        } else if(sqlite3StrICmp(zRight, SQLCIPHER_PBKDF2_HMAC_SHA256_LABEL) == 0) {
          rc = sqlcipher_codec_ctx_set_kdf_algorithm(ctx, SQLCIPHER_PBKDF2_HMAC_SHA256);
        } else if(sqlite3StrICmp(zRight, SQLCIPHER_PBKDF2_HMAC_SHA512_LABEL) == 0) {
          rc = sqlcipher_codec_ctx_set_kdf_algorithm(ctx, SQLCIPHER_PBKDF2_HMAC_SHA512);
        }
        if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
      } else {
        int algorithm = sqlcipher_codec_ctx_get_kdf_algorithm(ctx);
        if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA1) {
          codec_vdbe_return_string(pParse, "cipher_kdf_algorithm", SQLCIPHER_PBKDF2_HMAC_SHA1_LABEL, P4_TRANSIENT);
        } else if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA256) {
          codec_vdbe_return_string(pParse, "cipher_kdf_algorithm", SQLCIPHER_PBKDF2_HMAC_SHA256_LABEL, P4_TRANSIENT);
        } else if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA512) {
          codec_vdbe_return_string(pParse, "cipher_kdf_algorithm", SQLCIPHER_PBKDF2_HMAC_SHA512_LABEL, P4_TRANSIENT);
        }
      }
    }
  }else 
  if( sqlite3StrICmp(zLeft,"cipher_default_kdf_algorithm")==0 ){
    if(zRight) {
      rc = SQLITE_ERROR;
      if(sqlite3StrICmp(zRight, SQLCIPHER_PBKDF2_HMAC_SHA1_LABEL) == 0) {
        rc = sqlcipher_set_default_kdf_algorithm(SQLCIPHER_PBKDF2_HMAC_SHA1);
      } else if(sqlite3StrICmp(zRight, SQLCIPHER_PBKDF2_HMAC_SHA256_LABEL) == 0) {
        rc = sqlcipher_set_default_kdf_algorithm(SQLCIPHER_PBKDF2_HMAC_SHA256);
      } else if(sqlite3StrICmp(zRight, SQLCIPHER_PBKDF2_HMAC_SHA512_LABEL) == 0) {
        rc = sqlcipher_set_default_kdf_algorithm(SQLCIPHER_PBKDF2_HMAC_SHA512);
      }
    } else {
      int algorithm = sqlcipher_get_default_kdf_algorithm();
      if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA1) {
        codec_vdbe_return_string(pParse, "cipher_default_kdf_algorithm", SQLCIPHER_PBKDF2_HMAC_SHA1_LABEL, P4_TRANSIENT);
      } else if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA256) {
        codec_vdbe_return_string(pParse, "cipher_default_kdf_algorithm", SQLCIPHER_PBKDF2_HMAC_SHA256_LABEL, P4_TRANSIENT);
      } else if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA512) {
        codec_vdbe_return_string(pParse, "cipher_default_kdf_algorithm", SQLCIPHER_PBKDF2_HMAC_SHA512_LABEL, P4_TRANSIENT);
      }
    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_compatibility")==0 ){
    if(ctx) {
      if(zRight) {
        int version = atoi(zRight); 

        switch(version) {
          case 1: 
            rc = sqlcipher_codec_ctx_set_pagesize(ctx, 1024);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_hmac_algorithm(ctx, SQLCIPHER_HMAC_SHA1);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_kdf_algorithm(ctx, SQLCIPHER_PBKDF2_HMAC_SHA1);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_kdf_iter(ctx, 4000); 
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_use_hmac(ctx, 0);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            break;

          case 2: 
            rc = sqlcipher_codec_ctx_set_pagesize(ctx, 1024);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_hmac_algorithm(ctx, SQLCIPHER_HMAC_SHA1);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_kdf_algorithm(ctx, SQLCIPHER_PBKDF2_HMAC_SHA1);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_kdf_iter(ctx, 4000); 
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_use_hmac(ctx, 1);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            break;

          case 3:
            rc = sqlcipher_codec_ctx_set_pagesize(ctx, 1024);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_hmac_algorithm(ctx, SQLCIPHER_HMAC_SHA1);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_kdf_algorithm(ctx, SQLCIPHER_PBKDF2_HMAC_SHA1);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_kdf_iter(ctx, 64000); 
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_use_hmac(ctx, 1);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            break;

          default:
            rc = sqlcipher_codec_ctx_set_pagesize(ctx, 4096);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_hmac_algorithm(ctx, SQLCIPHER_HMAC_SHA512);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_kdf_algorithm(ctx, SQLCIPHER_PBKDF2_HMAC_SHA512);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_kdf_iter(ctx, 256000); 
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            rc = sqlcipher_codec_ctx_set_use_hmac(ctx, 1);
            if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
            break;
        }  

        rc = codec_set_btree_to_codec_pagesize(db, pDb, ctx);
        if (rc != SQLITE_OK) sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR);
      } 
    }
  }else 
  if( sqlite3StrICmp(zLeft,"cipher_default_compatibility")==0 ){
    if(zRight) {
      int version = atoi(zRight); 
      switch(version) {
        case 1: 
          sqlcipher_set_default_pagesize(1024);
          sqlcipher_set_default_hmac_algorithm(SQLCIPHER_HMAC_SHA1);
          sqlcipher_set_default_kdf_algorithm(SQLCIPHER_PBKDF2_HMAC_SHA1);
          sqlcipher_set_default_kdf_iter(4000);
          sqlcipher_set_default_use_hmac(0);
          break;

        case 2: 
          sqlcipher_set_default_pagesize(1024);
          sqlcipher_set_default_hmac_algorithm(SQLCIPHER_HMAC_SHA1);
          sqlcipher_set_default_kdf_algorithm(SQLCIPHER_PBKDF2_HMAC_SHA1);
          sqlcipher_set_default_kdf_iter(4000);
          sqlcipher_set_default_use_hmac(1);
          break;

        case 3:
          sqlcipher_set_default_pagesize(1024);
          sqlcipher_set_default_hmac_algorithm(SQLCIPHER_HMAC_SHA1);
          sqlcipher_set_default_kdf_algorithm(SQLCIPHER_PBKDF2_HMAC_SHA1);
          sqlcipher_set_default_kdf_iter(64000);
          sqlcipher_set_default_use_hmac(1);
          break;

        default:
          sqlcipher_set_default_pagesize(4096);
          sqlcipher_set_default_hmac_algorithm(SQLCIPHER_HMAC_SHA512);
          sqlcipher_set_default_kdf_algorithm(SQLCIPHER_PBKDF2_HMAC_SHA512);
          sqlcipher_set_default_kdf_iter(256000);
          sqlcipher_set_default_use_hmac(1);
          break;
      }  
    } 
  }else 
  if( sqlite3StrICmp(zLeft,"cipher_memory_security")==0 ){
    if( zRight ) {
      sqlcipher_set_mem_security(sqlite3GetBoolean(zRight,1));
    } else {
      char *on = sqlite3_mprintf("%d", sqlcipher_get_mem_security());
      codec_vdbe_return_string(pParse, "cipher_memory_security", on, P4_DYNAMIC);
    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_settings")==0 ){
    if(ctx) {
      int algorithm;
      char *pragma;

      pragma = sqlite3_mprintf("PRAGMA kdf_iter = %d;", sqlcipher_codec_ctx_get_kdf_iter(ctx));
      codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

      pragma = sqlite3_mprintf("PRAGMA cipher_page_size = %d;", sqlcipher_codec_ctx_get_pagesize(ctx));
      codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

      pragma = sqlite3_mprintf("PRAGMA cipher_use_hmac = %d;", sqlcipher_codec_ctx_get_use_hmac(ctx));
      codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

      pragma = sqlite3_mprintf("PRAGMA cipher_plaintext_header_size = %d;", sqlcipher_codec_ctx_get_plaintext_header_size(ctx));
      codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

      algorithm = sqlcipher_codec_ctx_get_hmac_algorithm(ctx);
      pragma = NULL;
      if(algorithm == SQLCIPHER_HMAC_SHA1) {
        pragma = sqlite3_mprintf("PRAGMA cipher_hmac_algorithm = %s;", SQLCIPHER_HMAC_SHA1_LABEL);
      } else if(algorithm == SQLCIPHER_HMAC_SHA256) {
        pragma = sqlite3_mprintf("PRAGMA cipher_hmac_algorithm = %s;", SQLCIPHER_HMAC_SHA256_LABEL);
      } else if(algorithm == SQLCIPHER_HMAC_SHA512) {
        pragma = sqlite3_mprintf("PRAGMA cipher_hmac_algorithm = %s;", SQLCIPHER_HMAC_SHA512_LABEL);
      }
      codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

      algorithm = sqlcipher_codec_ctx_get_kdf_algorithm(ctx);
      pragma = NULL;
      if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA1) {
        pragma = sqlite3_mprintf("PRAGMA cipher_kdf_algorithm = %s;", SQLCIPHER_PBKDF2_HMAC_SHA1_LABEL);
      } else if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA256) {
        pragma = sqlite3_mprintf("PRAGMA cipher_kdf_algorithm = %s;", SQLCIPHER_PBKDF2_HMAC_SHA256_LABEL);
      } else if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA512) {
        pragma = sqlite3_mprintf("PRAGMA cipher_kdf_algorithm = %s;", SQLCIPHER_PBKDF2_HMAC_SHA512_LABEL);
      }
      codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

    }
  }else
  if( sqlite3StrICmp(zLeft,"cipher_default_settings")==0 ){
    int algorithm;
    char *pragma;

    pragma = sqlite3_mprintf("PRAGMA cipher_default_kdf_iter = %d;", sqlcipher_get_default_kdf_iter());
    codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

    pragma = sqlite3_mprintf("PRAGMA cipher_default_page_size = %d;", sqlcipher_get_default_pagesize());
    codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

    pragma = sqlite3_mprintf("PRAGMA cipher_default_use_hmac = %d;", sqlcipher_get_default_use_hmac());
    codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

    pragma = sqlite3_mprintf("PRAGMA cipher_default_plaintext_header_size = %d;", sqlcipher_get_default_plaintext_header_size());
    codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

    algorithm = sqlcipher_get_default_hmac_algorithm();
    pragma = NULL;
    if(algorithm == SQLCIPHER_HMAC_SHA1) {
      pragma = sqlite3_mprintf("PRAGMA cipher_default_hmac_algorithm = %s;", SQLCIPHER_HMAC_SHA1_LABEL);
    } else if(algorithm == SQLCIPHER_HMAC_SHA256) {
      pragma = sqlite3_mprintf("PRAGMA cipher_default_hmac_algorithm = %s;", SQLCIPHER_HMAC_SHA256_LABEL);
    } else if(algorithm == SQLCIPHER_HMAC_SHA512) {
      pragma = sqlite3_mprintf("PRAGMA cipher_default_hmac_algorithm = %s;", SQLCIPHER_HMAC_SHA512_LABEL);
    }
    codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);

    algorithm = sqlcipher_get_default_kdf_algorithm();
    pragma = NULL;
    if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA1) {
      pragma = sqlite3_mprintf("PRAGMA cipher_default_kdf_algorithm = %s;", SQLCIPHER_PBKDF2_HMAC_SHA1_LABEL);
    } else if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA256) {
      pragma = sqlite3_mprintf("PRAGMA cipher_default_kdf_algorithm = %s;", SQLCIPHER_PBKDF2_HMAC_SHA256_LABEL);
    } else if(algorithm == SQLCIPHER_PBKDF2_HMAC_SHA512) {
      pragma = sqlite3_mprintf("PRAGMA cipher_default_kdf_algorithm = %s;", SQLCIPHER_PBKDF2_HMAC_SHA512_LABEL);
    }
    codec_vdbe_return_string(pParse, "pragma", pragma, P4_DYNAMIC);
  }else {
    return 0;
  }
  return 1;
}

/* these constants are used internally within SQLite's pager.c to differentiate between
   operations on the main database or journal pages. This is important in the context
   of a rekey operations, where the journal must be written using the original key 
   material (to allow a transactional rollback), while the new database pages are being
   written with the new key material*/
#define CODEC_READ_OP 3
#define CODEC_WRITE_OP 6
#define CODEC_JOURNAL_OP 7

/*
 * sqlite3Codec can be called in multiple modes.
 * encrypt mode - expected to return a pointer to the 
 *   encrypted data without altering pData.
 * decrypt mode - expected to return a pointer to pData, with
 *   the data decrypted in the input buffer
 */
static void* sqlite3Codec(void *iCtx, void *data, Pgno pgno, int mode) {
  codec_ctx *ctx = (codec_ctx *) iCtx;
  int offset = 0, rc = 0;
  int page_sz = sqlcipher_codec_ctx_get_pagesize(ctx); 
  unsigned char *pData = (unsigned char *) data;
  void *buffer = sqlcipher_codec_ctx_get_data(ctx);
  int plaintext_header_sz = sqlcipher_codec_ctx_get_plaintext_header_size(ctx);
  int cctx = CIPHER_READ_CTX;

  CODEC_TRACE("sqlite3Codec: entered pgno=%d, mode=%d, page_sz=%d\n", pgno, mode, page_sz);

#ifdef SQLCIPHER_LICENSE
  if(sqlcipher_license_check(ctx) != SQLITE_OK) return NULL;
#endif

  /* call to derive keys if not present yet */
  if((rc = sqlcipher_codec_key_derive(ctx)) != SQLITE_OK) {
   sqlcipher_codec_ctx_set_error(ctx, rc); 
   return NULL;
  }

  if(pgno == 1) /* adjust starting pointers in data page for header offset on first page*/   
    offset = plaintext_header_sz ? plaintext_header_sz : FILE_HEADER_SZ; 
  

  CODEC_TRACE("sqlite3Codec: switch mode=%d offset=%d\n",  mode, offset);
  switch(mode) {
    case CODEC_READ_OP: /* decrypt */
      if(pgno == 1) /* copy initial part of file header or SQLite magic to buffer */ 
        memcpy(buffer, plaintext_header_sz ? pData : (void *) SQLITE_FILE_HEADER, offset); 

      rc = sqlcipher_page_cipher(ctx, cctx, pgno, CIPHER_DECRYPT, page_sz - offset, pData + offset, (unsigned char*)buffer + offset);
      if(rc != SQLITE_OK) { /* clear results of failed cipher operation and set error */
        sqlcipher_memset((unsigned char*) buffer+offset, 0, page_sz-offset);
        sqlcipher_codec_ctx_set_error(ctx, rc);
      }
      memcpy(pData, buffer, page_sz); /* copy buffer data back to pData and return */
      return pData;
      break;

    case CODEC_WRITE_OP: /* encrypt database page, operate on write context and fall through to case 7, so the write context is used*/
      cctx = CIPHER_WRITE_CTX; 

    case CODEC_JOURNAL_OP: /* encrypt journal page, operate on read context use to get the original page data from the database */ 
      if(pgno == 1) { /* copy initial part of file header or salt to buffer */ 
        void *kdf_salt = NULL; 
        /* retrieve the kdf salt */
        if((rc = sqlcipher_codec_ctx_get_kdf_salt(ctx, &kdf_salt)) != SQLITE_OK) {
          sqlcipher_codec_ctx_set_error(ctx, rc); 
          return NULL;
        }
        memcpy(buffer, plaintext_header_sz ? pData : kdf_salt, offset); 
      }
      rc = sqlcipher_page_cipher(ctx, cctx, pgno, CIPHER_ENCRYPT, page_sz - offset, pData + offset, (unsigned char*)buffer + offset);
      if(rc != SQLITE_OK) { /* clear results of failed cipher operation and set error */
        sqlcipher_memset((unsigned char*)buffer+offset, 0, page_sz-offset);
        sqlcipher_codec_ctx_set_error(ctx, rc);
      }
      return buffer; /* return persistent buffer data, pData remains intact */
      break;

    default:
      sqlcipher_codec_ctx_set_error(ctx, SQLITE_ERROR); /* unsupported mode, set error */
      return pData;
      break;
  }
}

static void sqlite3FreeCodecArg(void *pCodecArg) {
  codec_ctx *ctx = (codec_ctx *) pCodecArg;
  if(pCodecArg == NULL) return;
  sqlcipher_codec_ctx_free(&ctx); /* wipe and free allocated memory for the context */
  sqlcipher_deactivate(); /* cleanup related structures, OpenSSL etc, when codec is detatched */
}

int sqlite3CodecAttach(sqlite3* db, int nDb, const void *zKey, int nKey) {
  struct Db *pDb = &db->aDb[nDb];

  CODEC_TRACE("sqlite3CodecAttach: entered db=%p, nDb=%d zKey=%s, nKey=%d\n", db, nDb, (char *)zKey, nKey);


  if(nKey && zKey && pDb->pBt) {
    int rc;
    Pager *pPager = pDb->pBt->pBt->pPager;
    sqlite3_file *fd;
    codec_ctx *ctx;

    /* check if the sqlite3_file is open, and if not force handle to NULL */ 
    if((fd = sqlite3PagerFile(pPager))->pMethods == 0) fd = NULL; 

    CODEC_TRACE("sqlite3CodecAttach: calling sqlcipher_activate()\n");
    sqlcipher_activate(); /* perform internal initialization for sqlcipher */

    CODEC_TRACE_MUTEX("sqlite3CodecAttach: entering database mutex %p\n", db->mutex);
    sqlite3_mutex_enter(db->mutex);
    CODEC_TRACE_MUTEX("sqlite3CodecAttach: entered database mutex %p\n", db->mutex);

#ifdef SQLCIPHER_LICENSE
    if((rc = sqlite3_set_authorizer(db, sqlcipher_license_authorizer, db)) != SQLITE_OK) {
      sqlite3_mutex_leave(db->mutex);
      return rc;
    }
#endif

    /* point the internal codec argument against the contet to be prepared */
    CODEC_TRACE("sqlite3CodecAttach: calling sqlcipher_codec_ctx_init()\n");
    rc = sqlcipher_codec_ctx_init(&ctx, pDb, pDb->pBt->pBt->pPager, zKey, nKey);

    if(rc != SQLITE_OK) {
      /* initialization failed, do not attach potentially corrupted context */
      CODEC_TRACE("sqlite3CodecAttach: context initialization failed with rc=%d\n", rc);
      CODEC_TRACE_MUTEX("sqlite3CodecAttach: leaving database mutex %p (early return on rc=%d)\n", db->mutex, rc);
      sqlite3_mutex_leave(db->mutex);
      CODEC_TRACE_MUTEX("sqlite3CodecAttach: left database mutex %p (early return on rc=%d)\n", db->mutex, rc);
      return rc;
    }

    CODEC_TRACE("sqlite3CodecAttach: calling sqlite3PagerSetCodec()\n");
    sqlite3PagerSetCodec(sqlite3BtreePager(pDb->pBt), sqlite3Codec, NULL, sqlite3FreeCodecArg, (void *) ctx);

    CODEC_TRACE("sqlite3CodecAttach: calling codec_set_btree_to_codec_pagesize()\n");
    codec_set_btree_to_codec_pagesize(db, pDb, ctx);

    /* force secure delete. This has the benefit of wiping internal data when deleted
       and also ensures that all pages are written to disk (i.e. not skipped by
       sqlite3PagerDontWrite optimizations) */ 
    CODEC_TRACE("sqlite3CodecAttach: calling sqlite3BtreeSecureDelete()\n");
    sqlite3BtreeSecureDelete(pDb->pBt, 1); 

    /* if fd is null, then this is an in-memory database and
       we dont' want to overwrite the AutoVacuum settings
       if not null, then set to the default */
    if(fd != NULL) { 
      CODEC_TRACE("sqlite3CodecAttach: calling sqlite3BtreeSetAutoVacuum()\n");
      sqlite3BtreeSetAutoVacuum(pDb->pBt, SQLITE_DEFAULT_AUTOVACUUM);
    }
    CODEC_TRACE_MUTEX("sqlite3CodecAttach: leaving database mutex %p\n", db->mutex);
    sqlite3_mutex_leave(db->mutex);
    CODEC_TRACE_MUTEX("sqlite3CodecAttach: left database mutex %p\n", db->mutex);
  }
  return SQLITE_OK;
}

int sqlcipher_find_db_index(sqlite3 *db, const char *zDb) {
  int db_index;
  if(zDb == NULL){
    return 0;
  }
  for(db_index = 0; db_index < db->nDb; db_index++) {
    struct Db *pDb = &db->aDb[db_index];
    if(strcmp(pDb->zDbSName, zDb) == 0) {
      return db_index;
    }
  }
  return 0;
}

void sqlite3_activate_see(const char* in) {
  /* do nothing, security enhancements are always active */
}

int sqlite3_key(sqlite3 *db, const void *pKey, int nKey) {
  CODEC_TRACE("sqlite3_key entered: db=%p pKey=%s nKey=%d\n", db, (char *)pKey, nKey);
  return sqlite3_key_v2(db, "main", pKey, nKey);
}

int sqlite3_key_v2(sqlite3 *db, const char *zDb, const void *pKey, int nKey) {
  CODEC_TRACE("sqlite3_key_v2: entered db=%p zDb=%s pKey=%s nKey=%d\n", db, zDb, (char *)pKey, nKey);
  /* attach key if db and pKey are not null and nKey is > 0 */
  if(db && pKey && nKey) {
    int db_index = sqlcipher_find_db_index(db, zDb);
    return sqlite3CodecAttach(db, db_index, pKey, nKey); 
  }
  return SQLITE_ERROR;
}

int sqlite3_rekey(sqlite3 *db, const void *pKey, int nKey) {
  CODEC_TRACE("sqlite3_rekey entered: db=%p pKey=%s nKey=%d\n", db, (char *)pKey, nKey);
  return sqlite3_rekey_v2(db, "main", pKey, nKey);
}

/* sqlite3_rekey_v2
** Given a database, this will reencrypt the database using a new key.
** There is only one possible modes of operation - to encrypt a database
** that is already encrpyted. If the database is not already encrypted
** this should do nothing
** The proposed logic for this function follows:
** 1. Determine if the database is already encryptped
** 2. If there is NOT already a key present do nothing
** 3. If there is a key present, re-encrypt the database with the new key
*/
int sqlite3_rekey_v2(sqlite3 *db, const char *zDb, const void *pKey, int nKey) {
  CODEC_TRACE("sqlite3_rekey_v2: entered db=%p zDb=%s pKey=%s, nKey=%d\n", db, zDb, (char *)pKey, nKey);
  if(db && pKey && nKey) {
    int db_index = sqlcipher_find_db_index(db, zDb);
    struct Db *pDb = &db->aDb[db_index];
    CODEC_TRACE("sqlite3_rekey_v2: database pDb=%p db_index:%d\n", pDb, db_index);
    if(pDb->pBt) {
      codec_ctx *ctx;
      int rc, page_count;
      Pgno pgno;
      PgHdr *page;
      Pager *pPager = pDb->pBt->pBt->pPager;

      ctx = (codec_ctx*) sqlite3PagerGetCodec(pDb->pBt->pBt->pPager);
     
      if(ctx == NULL) { 
        /* there was no codec attached to this database, so this should do nothing! */ 
        CODEC_TRACE("sqlite3_rekey_v2: no codec attached to db, exiting\n");
        return SQLITE_OK;
      }

      CODEC_TRACE_MUTEX("sqlite3_rekey_v2: entering database mutex %p\n", db->mutex);
      sqlite3_mutex_enter(db->mutex);
      CODEC_TRACE_MUTEX("sqlite3_rekey_v2: entered database mutex %p\n", db->mutex);

      codec_set_pass_key(db, db_index, pKey, nKey, CIPHER_WRITE_CTX);
    
      /* do stuff here to rewrite the database 
      ** 1. Create a transaction on the database
      ** 2. Iterate through each page, reading it and then writing it.
      ** 3. If that goes ok then commit and put ctx->rekey into ctx->key
      **    note: don't deallocate rekey since it may be used in a subsequent iteration 
      */
      rc = sqlite3BtreeBeginTrans(pDb->pBt, 1, 0); /* begin write transaction */
      sqlite3PagerPagecount(pPager, &page_count);
      for(pgno = 1; rc == SQLITE_OK && pgno <= (unsigned int)page_count; pgno++) { /* pgno's start at 1 see pager.c:pagerAcquire */
        if(!sqlite3pager_is_mj_pgno(pPager, pgno)) { /* skip this page (see pager.c:pagerAcquire for reasoning) */
          rc = sqlite3PagerGet(pPager, pgno, &page, 0);
          if(rc == SQLITE_OK) { /* write page see pager_incr_changecounter for example */
            rc = sqlite3PagerWrite(page);
            if(rc == SQLITE_OK) {
              sqlite3PagerUnref(page);
            } else {
             CODEC_TRACE("sqlite3_rekey_v2: error %d occurred writing page %d\n", rc, pgno);  
            }
          } else {
             CODEC_TRACE("sqlite3_rekey_v2: error %d occurred getting page %d\n", rc, pgno);  
          }
        } 
      }

      /* if commit was successful commit and copy the rekey data to current key, else rollback to release locks */
      if(rc == SQLITE_OK) { 
        CODEC_TRACE("sqlite3_rekey_v2: committing\n");
        rc = sqlite3BtreeCommit(pDb->pBt); 
        sqlcipher_codec_key_copy(ctx, CIPHER_WRITE_CTX);
      } else {
        CODEC_TRACE("sqlite3_rekey_v2: rollback\n");
        sqlite3BtreeRollback(pDb->pBt, SQLITE_ABORT_ROLLBACK, 0);
      }

      CODEC_TRACE_MUTEX("sqlite3_rekey_v2: leaving database mutex %p\n", db->mutex);
      sqlite3_mutex_leave(db->mutex);
      CODEC_TRACE_MUTEX("sqlite3_rekey_v2: left database mutex %p\n", db->mutex);
    }
    return SQLITE_OK;
  }
  return SQLITE_ERROR;
}

void sqlite3CodecGetKey(sqlite3* db, int nDb, void **zKey, int *nKey) {
  struct Db *pDb = &db->aDb[nDb];
  CODEC_TRACE("sqlite3CodecGetKey: entered db=%p, nDb=%d\n", db, nDb);
  if( pDb->pBt ) {
    codec_ctx *ctx = (codec_ctx*) sqlite3PagerGetCodec(pDb->pBt->pBt->pPager);
    
    if(ctx) {
      /* pass back the keyspec from the codec, unless PRAGMA cipher_store_pass
         is set or keyspec has not yet been derived, in which case pass
         back the password key material */
      sqlcipher_codec_get_keyspec(ctx, zKey, nKey);
      if(sqlcipher_codec_get_store_pass(ctx) == 1 || *zKey == NULL) {
        sqlcipher_codec_get_pass(ctx, zKey, nKey);
      }
    } else {
      *zKey = NULL;
      *nKey = 0;
    }
  }
}

#if defined (SQLCIPHER_PREPROCESSED)
void cipher_hex2bin(const unsigned char *hex, int sz, unsigned char *out){
    int i;
    for(i = 0; i < sz; i += 2){
        out[i/2] = (cipher_hex2int(hex[i])<<4) | cipher_hex2int(hex[i+1]);
    }
}
#endif /* SQLCIPHER_PREPROCESSED */

#if defined (SQLCIPHER_PREPROCESSED)
void cipher_bin2hex(const unsigned char* in, int sz, char *out) {
    int i;
    for(i=0; i < sz; i++) {
        sqlite3_snprintf(3, out + (i*2), "%02x ", in[i]);
    }
}
#endif /* SQLCIPHER_PREPROCESSED */

#if defined (SQLCIPHER_PREPROCESSED)
int cipher_isHex(const unsigned char *hex, int sz){
    int i;
    for(i = 0; i < sz; i++) {
        unsigned char c = hex[i];
        if ((c < '0' || c > '9') &&
            (c < 'A' || c > 'F') &&
            (c < 'a' || c > 'f')) {
            return 0;
        }
    }
    return 1;
}
#endif /* SQLCIPHER_PREPROCESSED */


#ifndef OMIT_EXPORT

/*
 * Implementation of an "export" function that allows a caller
 * to duplicate the main database to an attached database. This is intended
 * as a conveneince for users who need to:
 * 
 *   1. migrate from an non-encrypted database to an encrypted database
 *   2. move from an encrypted database to a non-encrypted database
 *   3. convert beween the various flavors of encrypted databases.  
 *
 * This implementation is based heavily on the procedure and code used
 * in vacuum.c, but is exposed as a function that allows export to any
 * named attached database.
 */

/*
** Finalize a prepared statement.  If there was an error, store the
** text of the error message in *pzErrMsg.  Return the result code.
** 
** Based on vacuumFinalize from vacuum.c
*/
static int sqlcipher_finalize(sqlite3 *db, sqlite3_stmt *pStmt, char **pzErrMsg){
  int rc;
  rc = sqlite3VdbeFinalize((Vdbe*)pStmt);
  if( rc ){
    sqlite3SetString(pzErrMsg, db, sqlite3_errmsg(db));
  }
  return rc;
}

/*
** Execute zSql on database db. Return an error code.
** 
** Based on execSql from vacuum.c
*/
static int sqlcipher_execSql(sqlite3 *db, char **pzErrMsg, const char *zSql){
  sqlite3_stmt *pStmt;
  VVA_ONLY( int rc; )
  if( !zSql ){
    return SQLITE_NOMEM;
  }
  if( SQLITE_OK!=sqlite3_prepare(db, zSql, -1, &pStmt, 0) ){
    sqlite3SetString(pzErrMsg, db, sqlite3_errmsg(db));
    return sqlite3_errcode(db);
  }
  VVA_ONLY( rc = ) sqlite3_step(pStmt);
  assert( rc!=SQLITE_ROW );
  return sqlcipher_finalize(db, pStmt, pzErrMsg);
}

/*
** Execute zSql on database db. The statement returns exactly
** one column. Execute this as SQL on the same database.
** 
** Based on execExecSql from vacuum.c
*/
static int sqlcipher_execExecSql(sqlite3 *db, char **pzErrMsg, const char *zSql){
  sqlite3_stmt *pStmt;
  int rc;

  rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
  if( rc!=SQLITE_OK ) return rc;

  while( SQLITE_ROW==sqlite3_step(pStmt) ){
    rc = sqlcipher_execSql(db, pzErrMsg, (char*)sqlite3_column_text(pStmt, 0));
    if( rc!=SQLITE_OK ){
      sqlcipher_finalize(db, pStmt, pzErrMsg);
      return rc;
    }
  }

  return sqlcipher_finalize(db, pStmt, pzErrMsg);
}

/*
 * copy database and schema from the main database to an attached database
 * 
 * Based on sqlite3RunVacuum from vacuum.c
*/
void sqlcipher_exportFunc(sqlite3_context *context, int argc, sqlite3_value **argv) {
  sqlite3 *db = sqlite3_context_db_handle(context);
  const char* targetDb, *sourceDb; 
  int targetDb_idx = 0;
  u64 saved_flags = db->flags;        /* Saved value of the db->flags */
  u32 saved_mDbFlags = db->mDbFlags;        /* Saved value of the db->mDbFlags */
  int saved_nChange = db->nChange;      /* Saved value of db->nChange */
  int saved_nTotalChange = db->nTotalChange; /* Saved value of db->nTotalChange */
  u8 saved_mTrace = db->mTrace;        /* Saved value of db->mTrace */
  int (*saved_xTrace)(u32,void*,void*,void*) = db->xTrace; /* Saved db->xTrace */
  int rc = SQLITE_OK;     /* Return code from service routines */
  char *zSql = NULL;         /* SQL statements */
  char *pzErrMsg = NULL;

  if(argc != 1 && argc != 2) {
    rc = SQLITE_ERROR;
    pzErrMsg = sqlite3_mprintf("invalid number of arguments (%d) passed to sqlcipher_export", argc);
    goto end_of_export;
  }

  targetDb = (const char*) sqlite3_value_text(argv[0]);
  sourceDb = (argc == 2) ? (char *) sqlite3_value_text(argv[1]) : "main";

  /* if the name of the target is not main, but the index returned is zero 
     there is a mismatch and we should not proceed */
  targetDb_idx =  sqlcipher_find_db_index(db, targetDb);
  if(targetDb_idx == 0 && sqlite3StrICmp("main", targetDb) != 0) {
    rc = SQLITE_ERROR;
    pzErrMsg = sqlite3_mprintf("unknown database %s", targetDb);
    goto end_of_export;
  }
  db->init.iDb = targetDb_idx;

  db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks; 
  db->mDbFlags |= DBFLAG_PreferBuiltin | DBFLAG_Vacuum;
  db->flags &= ~(u64)(SQLITE_ForeignKeys | SQLITE_ReverseOrder | SQLITE_Defensive | SQLITE_CountRows); 
  db->xTrace = 0;
  db->mTrace = 0;

  /* Query the schema of the main database. Create a mirror schema
  ** in the temporary database.
  */
  zSql = sqlite3_mprintf(
    "SELECT sql "
    "  FROM %s.sqlite_master WHERE type='table' AND name!='sqlite_sequence'"
    "   AND rootpage>0"
  , sourceDb);
  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
  if( rc!=SQLITE_OK ) goto end_of_export;
  sqlite3_free(zSql);

  zSql = sqlite3_mprintf(
    "SELECT sql "
    "  FROM %s.sqlite_master WHERE sql LIKE 'CREATE INDEX %%' "
  , sourceDb);
  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
  if( rc!=SQLITE_OK ) goto end_of_export;
  sqlite3_free(zSql);

  zSql = sqlite3_mprintf(
    "SELECT sql "
    "  FROM %s.sqlite_master WHERE sql LIKE 'CREATE UNIQUE INDEX %%'"
  , sourceDb);
  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
  if( rc!=SQLITE_OK ) goto end_of_export;
  sqlite3_free(zSql);

  /* Loop through the tables in the main database. For each, do
  ** an "INSERT INTO rekey_db.xxx SELECT * FROM main.xxx;" to copy
  ** the contents to the temporary database.
  */
  zSql = sqlite3_mprintf(
    "SELECT 'INSERT INTO %s.' || quote(name) "
    "|| ' SELECT * FROM %s.' || quote(name) || ';'"
    "FROM %s.sqlite_master "
    "WHERE type = 'table' AND name!='sqlite_sequence' "
    "  AND rootpage>0"
  , targetDb, sourceDb, sourceDb);
  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
  if( rc!=SQLITE_OK ) goto end_of_export;
  sqlite3_free(zSql);

  /* Copy over the contents of the sequence table
  */
  zSql = sqlite3_mprintf(
    "SELECT 'INSERT INTO %s.' || quote(name) "
    "|| ' SELECT * FROM %s.' || quote(name) || ';' "
    "FROM %s.sqlite_master WHERE name=='sqlite_sequence';"
  , targetDb, sourceDb, targetDb);
  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execExecSql(db, &pzErrMsg, zSql); 
  if( rc!=SQLITE_OK ) goto end_of_export;
  sqlite3_free(zSql);

  /* Copy the triggers, views, and virtual tables from the main database
  ** over to the temporary database.  None of these objects has any
  ** associated storage, so all we have to do is copy their entries
  ** from the SQLITE_MASTER table.
  */
  zSql = sqlite3_mprintf(
    "INSERT INTO %s.sqlite_master "
    "  SELECT type, name, tbl_name, rootpage, sql"
    "    FROM %s.sqlite_master"
    "   WHERE type='view' OR type='trigger'"
    "      OR (type='table' AND rootpage=0)"
  , targetDb, sourceDb);
  rc = (zSql == NULL) ? SQLITE_NOMEM : sqlcipher_execSql(db, &pzErrMsg, zSql); 
  if( rc!=SQLITE_OK ) goto end_of_export;
  sqlite3_free(zSql);

  zSql = NULL;
end_of_export:
  db->init.iDb = 0;
  db->flags = saved_flags;
  db->mDbFlags = saved_mDbFlags;
  db->nChange = saved_nChange;
  db->nTotalChange = saved_nTotalChange;
  db->xTrace = saved_xTrace;
  db->mTrace = saved_mTrace;

  if(zSql) sqlite3_free(zSql);

  if(rc) {
    if(pzErrMsg != NULL) {
      sqlite3_result_error(context, pzErrMsg, -1);
      sqlite3DbFree(db, pzErrMsg);
    } else {
      sqlite3_result_error(context, sqlite3ErrStr(rc), -1);
    }
  }
}

#endif

/* END SQLCIPHER */
#endif
