diff --git a/native/media/encryption-utils.js b/native/media/encryption-utils.js
index c4c839006..12b6a43e2 100644
--- a/native/media/encryption-utils.js
+++ b/native/media/encryption-utils.js
@@ -1,382 +1,386 @@
 // @flow
 
 import invariant from 'invariant';
-import filesystem from 'react-native-fs';
 
-import {
-  base64FromIntArray,
-  uintArrayToHexString,
-  hexToUintArray,
-} from 'lib/media/data-utils.js';
+import { uintArrayToHexString, hexToUintArray } from 'lib/media/data-utils.js';
 import {
   replaceExtension,
   fileInfoFromData,
   readableFilename,
   pathFromURI,
 } from 'lib/media/file-utils.js';
 import type {
   MediaMissionFailure,
   MediaMissionStep,
   EncryptFileMediaMissionStep,
 } from 'lib/types/media-types.js';
 import { getMessageForException } from 'lib/utils/errors.js';
 import { pad, unpad, calculatePaddedLength } from 'lib/utils/pkcs7-padding.js';
 
 import { temporaryDirectoryPath } from './file-utils.js';
 import { getFetchableURI } from './identifier-utils.js';
 import type { MediaResult } from './media-utils.js';
+import { commUtilsModule } from '../native-modules.js';
 import * as AES from '../utils/aes-crypto-module.js';
 
 const PADDING_THRESHOLD = 5000000; // we don't pad files larger than this
 
 type EncryptedFileResult = {
   +success: true,
   +uri: string,
   +encryptionKey: string,
 };
 
 /**
  * Encrypts a single file and returns the encrypted file URI
  * and the encryption key. The encryption key is returned as a hex string.
  * The encrypted file is written to the same directory as the original file,
  * with the same name, but with the extension ".dat".
  *
  * @param uri uri to the file to encrypt
  * @returns encryption result along with mission steps
  */
 async function encryptFile(uri: string): Promise<{
   steps: $ReadOnlyArray<EncryptFileMediaMissionStep>,
   result: MediaMissionFailure | EncryptedFileResult,
 }> {
   let success = true,
     exceptionMessage;
   const steps: EncryptFileMediaMissionStep[] = [];
-  const destination = replaceExtension(uri, 'dat');
+  const destinationURI = replaceExtension(uri, 'dat');
+  const destination = pathFromURI(destinationURI);
+  invariant(destination, `uri must be a local file:// path: ${destinationURI}`);
 
   // Step 1. Read the file
   const startOpenFile = Date.now();
   let data;
   try {
-    const response = await fetch(getFetchableURI(uri));
-    const buffer = await response.arrayBuffer();
-    data = new Uint8Array(buffer);
+    const path = pathFromURI(uri);
+    // for local paths (file:// URI) we can use native module which is faster
+    if (path) {
+      const buffer = await commUtilsModule.readBufferFromFile(path);
+      data = new Uint8Array(buffer);
+    } else {
+      const response = await fetch(getFetchableURI(uri));
+      const buffer = await response.arrayBuffer();
+      data = new Uint8Array(buffer);
+    }
   } catch (e) {
     success = false;
     exceptionMessage = getMessageForException(e);
   }
   steps.push({
     step: 'read_plaintext_file',
     file: uri,
     time: Date.now() - startOpenFile,
     success,
     exceptionMessage,
   });
   if (!success || !data) {
     return {
       steps,
       result: { success: false, reason: 'fetch_failed' },
     };
   }
 
   // Step 2. Encrypt the file
   const startEncrypt = Date.now();
   const paddedLength = calculatePaddedLength(data.byteLength);
   const shouldPad = paddedLength <= PADDING_THRESHOLD;
   let key, encryptedData;
   try {
     const plaintextData = shouldPad ? pad(data) : data;
     key = AES.generateKey();
     encryptedData = AES.encrypt(key, plaintextData);
   } catch (e) {
     success = false;
     exceptionMessage = getMessageForException(e);
   }
   steps.push({
     step: 'encrypt_data',
     dataSize: encryptedData?.byteLength ?? -1,
     isPadded: shouldPad,
     time: Date.now() - startEncrypt,
     success,
     exceptionMessage,
   });
   if (!success || !encryptedData || !key) {
     return {
       steps,
       result: { success: false, reason: 'encryption_failed' },
     };
   }
 
   // Step 3. Write the encrypted file
   const startWriteFile = Date.now();
   try {
-    const targetBase64 = base64FromIntArray(encryptedData);
-    await filesystem.writeFile(destination, targetBase64, 'base64');
+    await commUtilsModule.writeBufferToFile(destination, encryptedData.buffer);
   } catch (e) {
     success = false;
     exceptionMessage = getMessageForException(e);
   }
   steps.push({
     step: 'write_encrypted_file',
     file: destination,
     time: Date.now() - startWriteFile,
     success,
     exceptionMessage,
   });
   if (!success) {
     return {
       steps,
       result: { success: false, reason: 'write_file_failed' },
     };
   }
 
   return {
     steps,
     result: {
       success: true,
-      uri: destination,
+      uri: destinationURI,
       encryptionKey: uintArrayToHexString(key),
     },
   };
 }
 
 /**
  * Encrypts a single photo or video. Replaces the uploadURI with the encrypted
  * file URI. Attaches `encryptionKey` to the result. Changes the mediaType to
  * `encrypted_photo` or `encrypted_video`.
  *
  * @param preprocessedMedia - Result of `processMedia()` call
  * @returns a `preprocessedMedia` param, but with encryption applied
  */
 async function encryptMedia(preprocessedMedia: MediaResult): Promise<{
   result: MediaResult | MediaMissionFailure,
   steps: $ReadOnlyArray<MediaMissionStep>,
 }> {
   invariant(preprocessedMedia.success, 'encryptMedia called on failure result');
   invariant(
     preprocessedMedia.mediaType === 'photo' ||
       preprocessedMedia.mediaType === 'video',
     'encryptMedia should only be called on unencrypted photos and videos',
   );
   const { uploadURI } = preprocessedMedia;
   const steps = [];
 
   // Encrypt the media file
   const { steps: encryptionSteps, result: encryptionResult } =
     await encryptFile(uploadURI);
   steps.push(...encryptionSteps);
 
   if (!encryptionResult.success) {
     return { steps, result: encryptionResult };
   }
 
   if (preprocessedMedia.mediaType === 'photo') {
     return {
       steps,
       result: {
         ...preprocessedMedia,
         mediaType: 'encrypted_photo',
         uploadURI: encryptionResult.uri,
         encryptionKey: encryptionResult.encryptionKey,
         shouldDisposePath: pathFromURI(encryptionResult.uri),
       },
     };
   }
 
   // For videos, we also need to encrypt the thumbnail
   const { steps: thumbnailEncryptionSteps, result: thumbnailEncryptionResult } =
     await encryptFile(preprocessedMedia.uploadThumbnailURI);
   steps.push(...thumbnailEncryptionSteps);
 
   if (!thumbnailEncryptionResult.success) {
     return { steps, result: thumbnailEncryptionResult };
   }
 
   return {
     steps,
     result: {
       ...preprocessedMedia,
       mediaType: 'encrypted_video',
       uploadURI: encryptionResult.uri,
       encryptionKey: encryptionResult.encryptionKey,
       uploadThumbnailURI: thumbnailEncryptionResult.uri,
       thumbnailEncryptionKey: thumbnailEncryptionResult.encryptionKey,
       shouldDisposePath: pathFromURI(encryptionResult.uri),
     },
   };
 }
 
 type DecryptFileStep =
   | {
       +step: 'fetch_file',
       +file: string,
       +time: number,
       +success: boolean,
       +exceptionMessage: ?string,
     }
   | {
       +step: 'decrypt_data',
       +dataSize: number,
       +time: number,
       +isPadded: boolean,
       +success: boolean,
       +exceptionMessage: ?string,
     }
   | {
       +step: 'write_file',
       +file: string,
       +mimeType: string,
       +time: number,
       +success: boolean,
       +exceptionMessage: ?string,
     }
   | {
       +step: 'create_data_uri',
       +mimeType: string,
       +time: number,
       +success: boolean,
       +exceptionMessage: ?string,
     };
 type DecryptionFailure =
   | MediaMissionFailure
   | {
       +success: false,
       +reason:
         | 'fetch_file_failed'
         | 'decrypt_data_failed'
         | 'write_file_failed',
       +exceptionMessage: ?string,
     };
 
 async function decryptMedia(
   holder: string,
   encryptionKey: string,
   options: { +destination: 'file' | 'data_uri' },
 ): Promise<{
   steps: $ReadOnlyArray<DecryptFileStep>,
   result: DecryptionFailure | { success: true, uri: string },
 }> {
   let success = true,
     exceptionMessage;
   const steps: DecryptFileStep[] = [];
 
   // Step 1. Fetch the file and convert it to a Uint8Array
   const fetchStartTime = Date.now();
   let data;
   try {
     const response = await fetch(getFetchableURI(holder));
     const buf = await response.arrayBuffer();
     data = new Uint8Array(buf);
   } catch (e) {
     success = false;
     exceptionMessage = getMessageForException(e);
   }
   steps.push({
     step: 'fetch_file',
     file: holder,
     time: Date.now() - fetchStartTime,
     success,
     exceptionMessage,
   });
   if (!success || !data) {
     return {
       steps,
       result: { success: false, reason: 'fetch_file_failed', exceptionMessage },
     };
   }
 
   // Step 2. Decrypt the data
   const decryptionStartTime = Date.now();
   let plaintextData, decryptedData, isPadded;
   try {
     const key = hexToUintArray(encryptionKey);
     plaintextData = AES.decrypt(key, data);
     isPadded = plaintextData.byteLength <= PADDING_THRESHOLD;
     decryptedData = isPadded ? unpad(plaintextData) : plaintextData;
   } catch (e) {
     success = false;
     exceptionMessage = getMessageForException(e);
   }
   steps.push({
     step: 'decrypt_data',
     dataSize: decryptedData?.byteLength ?? -1,
     isPadded: !!isPadded,
     time: Date.now() - decryptionStartTime,
     success,
     exceptionMessage,
   });
 
   if (!success || !decryptedData) {
     return {
       steps,
       result: {
         success: false,
         reason: 'decrypt_data_failed',
         exceptionMessage,
       },
     };
   }
 
   // Step 3. Write the file to disk or create a data URI
   let uri;
   const writeStartTime = Date.now();
   // we need extension for react-native-video to work
   const { mime } = fileInfoFromData(decryptedData);
   if (!mime) {
     return {
       steps,
       result: {
         success: false,
         reason: 'mime_check_failed',
         mime,
       },
     };
   }
-  const base64 = base64FromIntArray(decryptedData);
   if (options.destination === 'file') {
     // if holder is a URL, then we use the last part of the path as the filename
     const holderSuffix = holder.substring(holder.lastIndexOf('/') + 1);
     const filename = readableFilename(holderSuffix, mime) || holderSuffix;
     const targetPath = `${temporaryDirectoryPath}${Date.now()}-${filename}`;
     try {
-      await filesystem.writeFile(targetPath, base64, 'base64');
+      await commUtilsModule.writeBufferToFile(targetPath, decryptedData.buffer);
     } catch (e) {
       success = false;
       exceptionMessage = getMessageForException(e);
     }
     uri = `file://${targetPath}`;
     steps.push({
       step: 'write_file',
       file: uri,
       mimeType: mime,
       time: Date.now() - writeStartTime,
       success,
       exceptionMessage,
     });
     if (!success) {
       return {
         steps,
         result: {
           success: false,
           reason: 'write_file_failed',
           exceptionMessage,
         },
       };
     }
   } else {
+    const base64 = commUtilsModule.base64EncodeBuffer(decryptedData.buffer);
     uri = `data:${mime};base64,${base64}`;
     steps.push({
       step: 'create_data_uri',
       mimeType: mime,
       time: Date.now() - writeStartTime,
       success,
       exceptionMessage,
     });
   }
 
   return {
     steps,
     result: { success: true, uri },
   };
 }
 
 export { encryptMedia, decryptMedia };