Android FDE ≤ 4.3 Hash

What is Android FDE ≤ 4.3?

The **Android Full Disk Encryption (FDE) ≤ 4.3** cryptographic scheme employs a hybrid approach combining **SHA-1-based key derivation** with **AES-256 in CTR mode** for disk encryption, rooted in Android’s pre-KitKat (4.4) encryption framework. Introduced in **Android 4.0 Ice Cream Sandwich (2011)**, this format leverages the **Android’s keystore system** to derive a **256-bit AES key** from the user’s PIN, password, or pattern via a multi-stage process: first, the input is hashed with **SHA-1**, then iterated via **PBKDF2-MD5** (with a fixed iteration count of **4096**), and finally combined with a **hardcoded salt** (derived from the device’s **IMEI/ESN**) to produce the encryption key. The resulting AES key encrypts the disk in **128-bit blocks** using CTR mode, with an optional **256-bit IV** (stored in the bootloader’s metadata) to ensure initialization vector uniqueness per encryption session. This scheme was primarily designed for **on-device performance**, prioritizing compatibility with older ARM-based processors while maintaining backward compatibility with legacy Android versions.

The vulnerability of this format stems from **fundamental cryptographic weaknesses and implementation flaws**. The reliance on **SHA-1** renders the key derivation susceptible to **length-extension attacks** and **preimage resistance failures**, as SHA-1’s collision resistance has been compromised since 2017. The **fixed iteration count of 4096 in PBKDF2-MD5** is insufficient for modern hardware, allowing brute-force attacks via **GPU-accelerated rainbow tables** or **dictionary attacks** when combined with weak user credentials. The **hardcoded salt derivation from IMEI/ESN** eliminates per-user uniqueness, enabling **batch attacks** where attackers can precompute hashes for common passwords. Additionally, the **CTR mode’s lack of integrity protection** (unlike GCM) allows for **bit-flipping attacks** if the IV is predictable or reused. Finally, the **absence of a salt in the key derivation** (despite PBKDF2’s requirement) and the **use of MD5 as a secondary hash** (after SHA-1) introduce **side-channel vulnerabilities** and **weak key stretching**, making recovery via **GPU clusters (e.g., Hashcat’s **android_fde** attack mode**) feasible within hours for weak passwords.

Identifying Android FDE ≤ 4.3 Hashes

Identifying a hash blindly is often difficult because multiple algorithms can output strings of the exact same length. For example, a standard 32-character hexadecimal string could be MD5, NTLM, MD4, or LM. To definitively identify Android FDE ≤ 4.3, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack Android FDE ≤ 4.3

If you need to recover the plaintext password for a Android FDE ≤ 4.3 hash during a penetration test or forensics investigation, you must supply the correct module ID to your cracking software. Use the exact commands provided at the top of this page to target the hash successfully.