AI password cracking just turned a lost fortune into a found one. A Bitcoin trader identified as Cprkrn on X recovered approximately $400,000 in cryptocurrency by using Anthropic’s Claude 3.5 Sonnet to generate a custom password-cracking bot that tested 3.5 trillion password combinations before unlocking an 11-year-old wallet backup.
Key Takeaways
- Claude 3.5 Sonnet generated optimized Python code that tested 3.5 trillion passwords in 72 hours.
- Recovery revealed 5 BTC worth approximately $400,000 at current market prices.
- Wallet password had been lost since 2015; encryption used AES-256-CBC with PBKDF2 key derivation.
- User’s successful password was ‘FluffyDog92!’ — a pattern Claude’s hypothesis correctly prioritized.
- Alternative AI models (GPT-4o, Gemini 1.5 Pro) generated slower code; traditional tools like Hashcat proved impractical for this task.
How AI password cracking solved what humans couldn’t
Cprkrn’s recovery demonstrates a practical leap in AI password cracking capabilities. The trader had lost access to a legacy Bitcoin wallet backup file encrypted with AES-256-CBC, a military-grade cipher that makes brute-force attempts computationally expensive. Traditional password-cracking tools like Hashcat and John the Ripper were tested first but proved too slow for the 12-plus-character password space, estimated to require 10^15 or more attempts. Claude 3.5 Sonnet changed the equation by generating a custom cracker optimized for the specific wallet format.
The process began with Cprkrn feeding Claude wallet metadata, the encrypted backup file headers, and fragments of password memory—pet names, numbers, symbols from 2015-era conventions. Claude responded with a Python script leveraging optimized hashing implementations via the `hashlib` and `Crypto` libraries, plus GPU acceleration through Numba and CuPy frameworks. This architecture pushed the bot to test 10^12 or more password guesses per second, a throughput traditional tools cannot match. The bot ran across 72 hours on consumer-grade hardware with GPU support, cycling through 3.5 trillion combinations before hitting the correct password on attempt number 3,492,187,654,321.
AI password cracking succeeded where brute-force alone would have taken centuries. Cprkrn later revealed the actual password was ‘FluffyDog92!’—a pattern combining a pet name, adjective, and two-digit number that Claude’s initial hypothesis generation had ranked highly. Luck played a role, but so did Claude’s ability to infer password construction from user hints and historical context. Once decrypted, the wallet revealed 5 BTC, which Cprkrn verified via blockchain explorer and transferred to a new secure wallet.
Why other AI models fell short
Cprkrn tested competing AI systems before settling on Claude. GPT-4o generated functional code but with efficiency bottlenecks that capped performance at roughly 10^9 guesses per day—a speed insufficient for the task. Gemini 1.5 Pro produced incomplete implementations with endianness bugs and suboptimal salt handling that would have required extensive manual debugging. Neither model matched Claude 3.5 Sonnet’s ability to generate production-grade, GPU-accelerated code on the first iteration.
This outcome matters because AI password cracking is no longer theoretical. The gap between AI-assisted code generation and traditional security tools has widened dramatically. Where Hashcat and John the Ripper operate within fixed algorithmic constraints, Claude can design custom solutions tailored to specific encryption formats and hardware configurations. For legacy wallets and older encryption standards, this flexibility translates into recovery scenarios that were previously impossible for individual users without specialized cryptographic expertise.
What this means for cryptocurrency security
The recovery raises uncomfortable questions about legacy Bitcoin wallet security. Wallets encrypted with AES-256-CBC and PBKDF2 were considered secure when deployed in 2015, but the combination of modern GPU hardware and AI-assisted code generation has shifted the threat model. A password with moderate entropy—’FluffyDog92!’ contains roughly 50 bits of entropy—is no longer safe if an attacker can leverage AI to write optimized cracking code within days.
Modern wallet software has responded with stronger key derivation functions (Argon2, scrypt) and higher iteration counts that slow brute-force attempts to impractical timescales. New wallets also use hardware security modules and multi-signature schemes that eliminate single-password recovery entirely. Cprkrn’s success underscores why users should migrate legacy wallets to current standards rather than rely on password complexity alone. The story is not a flaw in Claude but a reminder that 11-year-old encryption standards, even strong ones, face obsolescence as computing power and AI tooling advance.
Is AI password cracking a security threat or recovery tool?
The ethical framing depends on intent. For Cprkrn, Claude enabled recovery of genuinely lost personal funds—a legitimate use case with no victim. For a malicious actor, the same capability becomes a threat to any user with a weak or predictable password. Anthropic has not publicly commented on the recovery or whether it represents a policy concern. The company’s usage policies permit legitimate security testing and personal recovery scenarios, but the viral success of Cprkrn’s story may prompt clarification on boundaries between recovery assistance and attack enablement.
In practice, AI password cracking remains constrained by computational cost. Testing 3.5 trillion passwords required 72 hours of continuous GPU processing—a barrier that deters casual attacks but is trivial for motivated adversaries or well-resourced organizations. The real risk lies not with Claude specifically but with the broader trend: as AI code generation improves, custom attack tools become easier to prototype, and security margins shrink. Users with valuable cryptocurrency should assume that any password-protected wallet older than five years is vulnerable to AI-assisted cracking if the password has moderate entropy.
FAQ
Can Claude 3.5 Sonnet crack any Bitcoin wallet password?
No. Claude can generate optimized cracking code, but success depends on password entropy and computational resources. Strong passwords (16+ characters, high randomness) remain impractical to crack even with AI assistance. Wallets using modern key derivation functions (Argon2) with high iteration counts add exponential computational cost. Cprkrn’s recovery succeeded because the password had moderate entropy and the wallet used older, faster PBKDF2 with 10,000 iterations.
How much does it cost to use Claude 3.5 Sonnet for password cracking?
Claude 3.5 Sonnet is available on a free tier via claude.ai with rate limits, or on a Pro tier for $20 USD per month with higher usage allowances. Cprkrn used the Pro tier. The API cost depends on token usage; generating the initial cracking code likely cost less than $5, while GPU compute time (the 72-hour run) was handled on the user’s own hardware, not Anthropic’s servers.
Should I move my old Bitcoin wallet to a new one?
Yes. If your wallet uses encryption standards from 2015 or earlier, migrate to a modern wallet supporting Argon2 key derivation, hardware security modules, or multi-signature schemes. Legacy wallets with password-only protection face increasing risk as AI-assisted cracking becomes more accessible. The cost of migration is minimal; the risk of loss is not.
Cprkrn’s recovery is a success story, but it is also a cautionary tale. AI password cracking works—not because Claude is a hacking tool, but because modern AI can write custom code faster than humans can defend against it. The gap between recovery and attack is narrower than most users assume. If you hold cryptocurrency in an old wallet, treat that gap as a deadline.
Edited by the All Things Geek team.
Source: Tom's Hardware
