How to Save SHSH Blobs and Downgrade iOS Devices Using Redsn0w

Published by Redsn0w Editorial Team • 8 min read
How to Save SHSH Blobs and Downgrade iOS Devices Using Redsn0w - redsn0w.org

SHSH blobs (Signature HaSH) are unique digital certificates generated by Apple’s TSS servers that authorize a device to install a specific iOS firmware. While Apple stops "signing" older iOS versions after new releases, A4 devices (such as the iPhone 4, iPod touch 4G, and iPad 1) allow users to dump valid on-device blobs and stitch them into custom IPSW files using Redsn0w.

Why Downgrade A4 Devices?

The iPhone 4 runs noticeably slower on its maximum firmware (iOS 7.1.2). Downgrading to iOS 6.1.3 or iOS 5.1.1 restores silky-smooth performance, vintage skeuomorphic UI animations, and compatibility with classic 32-bit iOS games.

Part 1: How to Fetch and Dump On-Device SHSH Blobs

If your device is currently running an unsigned firmware version you want to preserve:

  1. Launch Redsn0w (Windows / Mac) as Administrator.
  2. Click Extras > SHSH Blobs > Fetch.
  3. Connect your device via USB and follow the on-screen countdown to enter DFU mode.
  4. Redsn0w will execute its payload, extract the SHSH blobs directly from your device's NAND flash memory, and save a copy to your computer while automatically uploading a backup to Cydia servers.

Part 2: Stitching a Custom IPSW Firmware

To prepare a firmware that iTunes will accept without Apple's active signature:

  1. In Redsn0w, navigate to Extras > SHSH Blobs > Stitch.
  2. Click IPSW and select the clean official IPSW file downloaded from trusted firmware mirrors.
  3. Click Blobs and select either Local (browse to your .plist blob file) or Cydia (Redsn0w will query the Cydia server for your ECID).
  4. Redsn0w will stitch the blobs into the firmware and output a new file named NO_BB_..._stitched.ipsw.

Part 3: Restoring via Pwned DFU and iTunes

To avoid iTunes Error 1600 or Error 3194 during the restore:

  • In Redsn0w, click Extras > Pwned DFU and put your device into Pwned DFU mode.
  • Launch iTunes. iTunes will detect an iPhone in recovery state.
  • Hold down the Shift key (Windows) or Option/Alt key (Mac) and click Restore iPhone.
  • Select the stitched IPSW created by Redsn0w.
  • iTunes will restore your device seamlessly to the vintage iOS version!

Related Guides:

DFU & Pwned DFU Mode Guide → Bypass iTunes Restore Errors →