Crypto Wallet Security: Protect Keys and Seed Phrases

About 10 min read

With the spread of cryptocurrency based on encryption technology, wallet security has become the most critical issue for asset protection. According to Chainalysis's 2024 report, hacking losses related to cryptocurrency reached approximately $3.7 billion per year, with individual wallet breaches accounting for about 20% of the total. As of 2025, attacks exploiting DeFi protocol vulnerabilities and social engineering and phishing to steal seed phrases are on the rise. Unlike bank accounts, cryptocurrency is permanently lost if you lose your private key, and unauthorized transfers cannot be reversed due to the immutability of blockchain. This article explains the risks of each type of cryptocurrency wallet and how to securely manage private keys and seed phrases. We also introduce how to strengthen your exchange account password with Passtsuku.com.

What You Should Do

Cryptocurrency security is all about "managing your private keys." If you are a beginner, first set your exchange account password to 24 characters or more using Passtsuku.com and enable two-factor authentication with an authenticator app. Write your seed phrase on paper by hand and never store it on a digital device. Intermediate users should move long-term holdings to a hardware wallet and keep only the minimum assets needed for trading in a hot wallet. Consider engraving your seed phrase on a metal backup plate as well.

Types of Cryptocurrency Wallets and Their Risks

Risks of Hot Wallets

A hot wallet manages cryptocurrency while constantly connected to the internet. Exchange wallets, browser extension wallets (such as MetaMask), and mobile app wallets fall into this category. While highly convenient, there is always a risk of private key theft through malware infection or phishing attacks. In 2024, multiple fake extensions mimicking MetaMask appeared on the Chrome Web Store, making phishing protection knowledge essential. Cases were reported where private keys of users who installed them were stolen.

Exchange wallets carry the risk of losing assets if the exchange itself is hacked. In the 2018 Coincheck incident, approximately 58 billion yen worth of NEM was stolen, and in the 2022 FTX collapse, approximately $8 billion in customer assets were frozen. We recommend keeping only the minimum assets needed for trading in a hot wallet and moving long-term holdings to a cold wallet. As a guideline, keep 10% or less of your total assets in a hot wallet and manage the rest in an offline environment.

Safety of Cold Wallets

A cold wallet manages private keys in a state disconnected from the internet. Hardware wallets and paper wallets fall into this category. Since there is no risk of online attacks, they are suitable for long-term storage of large amounts of cryptocurrency. Hardware wallets store private keys in a secure element (tamper-resistant chip) within the device, and signing is completed entirely within the device, so even if the connected PC is infected with malware, the private key will not leak externally.

To enhance the safety of cold wallets, introducing hardware wallets with secure element chips (Amazon)is effective. However, hardware wallets also have caveats. If purchased second-hand or from unauthorized retailers, the firmware may have been tampered with, so always buy new from the manufacturer's official website.

Managing Private Keys and Seed Phrases

Secure Storage of Seed Phrases

A seed phrase (recovery phrase) is a combination of 12 or 24 English words used to restore a wallet. Under the BIP-39 standard, words are selected from a list of 2,048 words, so a 12-word seed phrase has 2 to the power of 128 (approximately 3.4 × 10 to the 38th) possible combinations, making brute-force guessing virtually impossible. Anyone who knows this phrase can access all assets in the wallet, so it must be stored with the highest level of security.

You must never store your seed phrase on a digital device. Saving it as a screenshot, text file, or in cloud storage is all dangerous. In 2023, a seed phrase screenshot was leaked through iCloud sync, and approximately $6.5 million worth of cryptocurrency was stolen. Write it by hand on paper and store it in a fireproof safe, or engrave it on a metal backup plate. Metal plates can withstand fire (up to 1,500°C) and flooding, making them more suitable for long-term storage than paper. Storing copies in multiple locations also reduces the risk of total loss from disasters or theft. See also our backup and recovery strategies.

Handling Private Keys

A private key is a cryptographic key required for sending cryptocurrency. It is a 256-bit random number based on elliptic curve cryptography (secp256k1), from which the public key and wallet address are derived one-way using hash functions. Never share your private key with anyone or enter it on a website. Legitimate services will never ask you to enter your private key. Any site or app that asks for your private key is almost certainly a phishing scam. A common misconception is that storing your private key in a password manager is safe, but considering the risk of the password manager itself being compromised, offline physical storage is the safest option.

Protecting Exchange Accounts

Set a Strong Password with Passtsuku.com

Cryptocurrency exchange accounts require the highest level of password strength as they are directly linked to financial assets. Use Passtsuku.com to generate a random password of 24 characters or more that includes uppercase letters, lowercase letters, numbers, and symbols. A 24-character random password has approximately 10 to the 47th power of combinations, requiring trillions of years to crack with current computing power. Set a different password for each exchange and manage them with a password manager. If you have issued API keys, set equally strong passwords for them and disable unnecessary permissions (such as withdrawal permissions).

Making Two-Factor Authentication Mandatory

Always set up two-factor authentication on your exchange accounts using an authenticator app (Google Authenticator, Authy) or a hardware security key. TOTP (Time-based One-Time Password) authenticator apps generate a 6-digit code every 30 seconds, providing a defense layer that prevents third parties from logging in even if your password is leaked. SMS authentication is not recommended for cryptocurrency management due to the risk of SIM swap attacks. In 2023, a SIM swap attack was used to hijack a cryptocurrency exchange account in the US, resulting in approximately $24 million being fraudulently transferred. Also enable two-factor authentication for withdrawals to add an additional defense layer against unauthorized transfers.

To systematically learn about cryptocurrency security, blockchain wallet security and key management guides (Amazon) are helpful references.

Security Comparison by Wallet Type

Choosing a wallet is a trade-off between convenience and security. Exchange wallets are the most convenient but carry the risk of exchange hacking or bankruptcy. Browser extension hot wallets are convenient for DeFi integration but are prone to being targeted by malware and phishing. Hardware wallets are the safest as private keys are protected offline, but they incur device purchase costs and operational overhead. Paper wallets can be created at zero cost but have risks of physical deterioration and loss, and the disadvantage of requiring import to a hot wallet when sending funds. We recommend using multiple wallets depending on your holdings and trading frequency.

Actions You Can Take Now

1. Update your cryptocurrency exchange passwords to 24 characters or more using Passtsuku.com and set up two-factor authentication with an authenticator app
2. Check that your seed phrase is not stored on any digital device (screenshots, text files, cloud) and if so, delete it and rewrite it by hand on paper
3. Enable two-factor authentication for exchange withdrawals and disable unnecessary API key permissions (withdrawal permissions)
4. Move long-term holdings to a hardware wallet (purchase new from the manufacturer official site)
5. Store the seed phrase paper in a fireproof safe and if possible, engrave it on a metal backup plate

Frequently Asked Questions

What is the difference between hot wallets and cold wallets?

Hot wallets are always connected to the internet, offering convenience but carrying hacking risks. Cold wallets manage private keys offline, providing higher security and suitability for long-term storage. It is recommended to keep large assets in cold wallets and only daily transaction amounts in hot wallets.

How should I store my seed phrase (recovery phrase)?

The basic approach is to write it by hand on paper and store it in a fireproof safe. Never save it on digital devices (phone notes, cloud storage, screenshots). Engraving on metal plates can withstand fire and water damage. Distributing copies across multiple secure locations adds extra safety.

How can I keep my cryptocurrency exchange account secure?

Set a unique strong password for each exchange and enable two-factor authentication with a hardware key. SMS authentication is vulnerable to SIM swap attacks, so authenticator apps or hardware keys are safer. If withdrawal address whitelisting is available, always enable it.