Reverse Engineering

// Crypto Wallet Reverse Engineering & Binary Analysis

When most people look at a cryptocurrency wallet, they see a balance and a send button. When I look at one, I see a compiled binary sitting on top of a signing engine, a key derivation framework, and a serialized transaction builder — all of which can be pulled apart, inspected, and understood at the instruction level. Reverse engineering crypto wallets is where low-level binary analysis meets applied cryptography, and it’s one of the more fascinating intersections in modern security work.

// The Approach

Every wallet — whether it’s a desktop Electron app, a mobile native binary, or a hardware wallet’s firmware image — follows the same fundamental pattern: generate or import keys, derive addresses from those keys, construct transactions, sign them, and broadcast. The devil is in the implementation. I start with static analysis in Ghidra or IDA Pro, mapping out the call graph to identify the cryptographic primitives: where is the BIP-39 mnemonic being generated? How is the entropy source seeded? Is the BIP-32 HD key derivation following spec, or has someone rolled their own path scheme? Once I have the function map, I move to dynamic analysis — hooking calls with Frida, setting breakpoints on the ECDSA signing routines, and watching how the wallet handles the private key material in memory.

// What I Look For

Key storage and memory hygiene. A properly implemented wallet should zero out private key buffers after signing. You’d be surprised how many don’t. I trace the lifecycle of key material from derivation through signing and check whether memset_s or equivalent secure erase functions are called. If the key sits in a heap-allocated buffer that just gets freed without zeroing, that’s a finding — especially on systems without ASLR or where memory can be paged to disk.

Entropy and randomness. The security of every wallet starts with the random number generator. I disassemble the entropy collection routines and verify they’re pulling from /dev/urandom or CryptGenRandom — not some homegrown PRNG seeded with time(). On hardware wallets, I look at whether the TRNG peripheral is properly configured and whether the firmware includes whitening or health checks on the raw entropy stream per NIST SP 800-90B.

Transaction serialization and signing. This is where things get interesting. I rebuild the transaction construction logic in a debugger, watching how inputs are selected (UTXO handling for Bitcoin, nonce management for Ethereum), how the signing hash is computed (SIGHASH_ALL vs. other modes), and whether the DER-encoded signature is properly validated before broadcast. I’ve found wallets that don’t check for low-S values per BIP-62, wallets that reuse k-values in ECDSA (catastrophic), and wallets that construct the signing preimage incorrectly for SegWit transactions.

// Tools of the Trade

My standard toolkit includes Ghidra and IDA Pro for static disassembly, Frida for dynamic instrumentation, radare2 for quick triage, and a custom set of Python scripts built on top of pyecc and bitcoinlib for verifying cryptographic operations independently. For hardware wallets, I use a Saleae logic analyzer for sniffing SPI/I2C buses, a JTAGulator for finding debug interfaces, and OpenOCD for firmware extraction. For Electron-based wallets (which is most of them these days), it’s often as simple as unpacking the ASAR archive and reading the JavaScript — though the interesting parts are usually in native Node addons compiled from C/C++.

// Why This Matters

Crypto wallets are vaults. They protect real value. And unlike a bank, there’s no fraud department to call when something goes wrong. When a wallet has a vulnerability in its key derivation, its transaction signing, or its secure storage implementation, people lose money — permanently. The work I do in this space is about pulling those implementations apart before the bad actors do, documenting what’s broken, and making sure it gets fixed. It’s painstaking, detail-oriented work that sits at the intersection of cryptography, systems programming, and old-school reverse engineering. And I wouldn’t have it any other way.