GrayKey Fails: Critical iPhone Forensic Limits Exposed | Darren Chaker

#GrayKey Fails: Legal Analysis and Limitations in iPhone Data Forensics By Darren Chaker

The forensic landscape for accessing encrypted iPhone data continues to evolve amidst advances in Apple’s security and legal scrutiny over privacy protections.

Legal Case Studies Illustrating GrayKey effectiveness and Other Tool Limitations

GrayKey Effectiveness: Legal Case Studies

United States v. Banwari, No. 3:23-cr-00062 (W.D.N.C. Jan 6, 2025)

The United States v. Banwari case provides one of the most comprehensive judicial examinations of GrayKey effectiveness limitations and law enforcement forensic challenges in accessing encrypted iPhone data.
This Western District of North Carolina decision reveals critical insights into the practical realities of mobile forensic extraction tools and their operational constraints within FBI Computer Analysis Response Team (CART) units.

FBI CART Resource Constraints and GrayKey Unavailability

Court testimony from Former Senior Examiner Victor Gibson Grose, who served with FBI CART in Charlotte from 2018 to 2021, illuminated significant resource limitations that directly impacted forensic capabilities.
The Charlotte CART unit operated under severe staffing constraints, handling digital forensics not only within their district but also supporting other districts due to retirements and staffing shortages in Wilmington and assistance needs in Greenville offices.
Critically, the FBI CART team in Charlotte did not acquire GrayKey technology until sometime in 2020, well after the COVID-19 pandemic disrupted normal operations.
This timeline gap proved decisive in the Banwari investigation.
FBI Examiner Grose initially charged out defendant’s iPhone X from evidence on August 16, 2018, following standard protocols for device examination, including checking physical state, power status, device model determination, and extraction feasibility assessment.
However, GrayKey was not available to FBI CART in Charlotte when Grose first charged out defendant’s iPhone X in 2018, representing a critical limitation in forensic capability during the initial investigation period.

Alternative Tool Limitations: Cellebrite and 4PC Requirements

The court’s findings reveal fundamental limitations in alternative forensic extraction tools available to law enforcement.
Examiner Grose testified that while FBI CART examiners had periodic access to other extraction software and hardware, namely Cellebrite and 4PC, both tools require a device to be unlocked to perform any extraction.
This requirement presents a circular problem: investigators need the passcode to unlock the device to use the tools designed to extract data from the device.
Despite defendant allegedly providing the passcode “032889” to agents on August 2, 2018, and this information being written on the evidence bag, Examiner Grose was unable to successfully extract data from the iPhone X during his 2018 examination attempt.
The examiner did not recall whether he tried the provided passcode but believed he would have followed standard protocols.

Repeated Extraction Failures and Technology Evolution

The case documents multiple failed extraction attempts spanning several years, illustrating the persistent challenges in iPhone forensic analysis.
Between January 31, 2020, and March 31, 2020, Examiner Grose again charged the iPhone X from evidence but remained unable to perform successful extraction.
Only after GrayKey became available to the Charlotte CART unit could any data be extracted.
Between February 10, 2021, and July 28, 2021, with GrayKey finally accessible, Examiner Grose achieved limited extraction success.
However, this extraction was restricted to surface-level data based on the iPhone’s “before first unlock” state.
Grose explained that iPhones operate in three distinct security states: “before first unlock” (minimal unencrypted information available), “after first unlock” (more information available but still encrypted), and fully unlocked (complete extraction capability).
The limited extraction yielded 16.22 gigabytes of data, representing only a fraction of the device’s total information.
A subsequent examination by FBI digital forensic examiner Lauren Haller in February 2024 proved more successful, extracting 40.22 gigabytes of data when the device appeared in “no passcode set” mode, demonstrating how device states and technology evolution significantly impact forensic outcomes.

People v. d’Estree, 2024 COA 106 (Colo. Ct. App. 2024)

The Colorado Court of Appeals decision in People v. d’Estree provides crucial insights into the unpredictable timeframes and resource demands associated with brute force mobile forensic attacks, highlighting another significant limitation in law enforcement’s digital investigation capabilities.

Cellebrite Brute Force Attack: Three-Month Timeline

In this case, law enforcement authorities resorted to a Cellebrite-driven brute force attack to crack the defendant’s six-digit PIN code.
The forensic process ultimately required three months of sustained computational effort to successfully decode the passcode.
This extended timeline demonstrates the substantial resource investment and operational delays that can result from relying on brute force methodologies in criminal investigations.
The three-month duration in d’Estree represents significant investigative delays that could impact prosecutorial timelines, statute of limitations considerations, and overall case management efficiency.
Such extended forensic processing periods may also raise Fourth Amendment reasonableness concerns regarding the duration of device seizure and analysis.

Judicial Recognition of Brute Force Uncertainty

More significantly, the Colorado appellate court emphasized the inherent uncertainty in brute force attack success rates and timelines.
The court noted that potential brute force durations for six-digit PIN codes could range “anywhere from a week to eleven years,” illustrating the massive variability in forensic extraction outcomes.
This judicial recognition of timeline uncertainty underscores the unreliable nature of brute force approaches as consistent investigative tools.
The court’s findings highlight several critical implications for law enforcement and digital forensics practitioners:

• • Resource Planning Challenges: The unpredictable timeline range makes it difficult for law enforcement agencies to allocate resources efficiently and plan investigative strategies.

• • Legal Timing Concerns: Extended and uncertain processing periods may impact speedy trial rights, warrant validity periods, and prosecutorial decision-making timelines.

• Privacy Duration Issues: Prolonged device seizure and analysis periods raise constitutional questions about reasonable search duration and individual privacy rights protection.

The d’Estree decision illustrates that even when GrayKey or similar advanced tools are unavailable, alternative brute force methods present their own substantial limitations and uncertainties, further constraining law enforcement’s digital forensic capabilities.

United States v. Lawhorn, No. 3:23-cr-00166 (D. Conn. Apr 3, 2025)

The FBI’s forensic software at that time was unable to bypass the locked and encrypted state of a seized iPhone 12.
Subsequent law enforcement efforts secured a warrant anticipating that advanced tools, unavailable to the FBI in 2021, would eventually access the device, illustrating reliance on evolving technology for such extractions.

In re Apple, Inc., 149 F. Supp. 3d 341 (E.D.N.Y 2016)

This landmark case highlighted the risks of data destruction associated with third-party “IP-Box” technology allegedly capable of bypassing iPhone security.
The government acknowledged non-trivial risks, including unintended activation of the iPhone’s erase data feature, rendering the target’s information permanently inaccessible — a critical caution in forensic operations.

Cooper v. Baltimore Gas and Electric Company, No. 1:23-cv-03116 (D. Maryland Apr 4, 2025)

The court noted forensic examiners’ uncertainty about mechanisms to unlock iPhones, aside from possible proprietary Apple workarounds not disclosed to retail outlets.
For all devices running iOS 8.0 and later, Apple confirmed inability to perform full data extraction as the relevant data is encrypted and Apple does not possess the decryption key.

United States v. Sullivan, No. 1:17-cr-00104 (D. Haw. Sep 4, 2020)

The court explained that while Cellebrite could extract data from the unencrypted portions of an iPhone, the encrypted data required a passcode for usability.
The IRS’s inability to access the passcode meant the encrypted data remained inaccessible, emphasizing ongoing technical challenges tied to encryption security.

Technical Realities and Challenges in iPhone Forensics and GrayKey effectiveness

Technological advancements by Apple, including periodic iOS updates, increasingly frustrate GrayKey-like exploits by patching known vulnerabilities. For instance, iOS 11.4.1 defeated GrayKey presumed effectiveness in bypassing security.

Frequently Asked Questions on GrayKey Effectiveness

Is GrayKey effective on all iPhones? No. Multiple court cases document failures due to security updates, hardware limitations, and encryption technology. Who is Darren Chaker? Darren Chaker is a privacy law authority, legal advocate, and published author on forensic technology and viewpoint discrimination.