An application programming interface (API) key is a unique code used by the API to identify the calling application or user. API keys are used to track and control who uses the API and how they use it, and to authenticate and authorize applications. They work similarly to usernames and passwords. API keys come in the form of a single key or a set of multiple keys. Users should follow best practices to improve overall security to prevent API key theft and avoid the consequences associated with API key compromise.

API and API Key

To understand what an API key is, You must first know what an API is. An application programming interface, or API, is a software intermediary that allows two or more applications to share information. For example, CoinMarketCap’s API allows other applications to retrieve and use cryptocurrency data such as price, trading volume and market capitalization.

API keys come in various forms, and can be a single key or a set of multiple keys. Different systems use these keys to authenticate and authorize applications, similar to how usernames and passwords are used. API clients use API keys to authenticate applications calling the API.

For example, assuming that Binance Academy wants to use the CoinMarketCap API, CoinMarketCap generates an API key, and in Binance Academy (API client ) used to verify their identity when requesting API access. When Binance Academy accesses CoinMarketCap’s API, it should send this API key to CoinMarketCap along with the request.

This API key is for Binance Academy only and may not be shared or sent to others. By sharing this API key, you are allowing third parties to access CoinMarketCap as Binance Academy, and any actions by third parties will appear as coming from Binance Academy.

CoinMarketCap API can also use API keys to confirm whether the application has permission to access the requested resources. In addition, API owners can use API keys to monitor API activity, such as the type, traffic, and volume of requests.

What is an API key?

API keys are used to control and track API users and how they use them. The term "API key" means different things for different systems. Some systems have a single code, others have multiple codes for a single "API key".

Therefore, an "API key" is a unique code or set of unique codes used by the API to authenticate and authorize the calling user or application code. Some code is used for verification, and some is used to create cryptographic signatures to prove the legitimacy of the request.

Verification codes are often collectively referred to as "API keys", and codes used for cryptographic signatures have different names, such as "encryption keys" key", "public key" or "private key". Authentication requires identifying the entities involved and confirming that they are who they claim to be.

On the other hand, authorization specifies the API services that are allowed to be accessed. API keys act like an account's username and password and can be connected to other security features to improve overall security.

Each API key is typically generated by the API owner as a specific entity (see details below) each time the API endpoint is called User authentication or authorization (or both) is required, and associated keys are used.

Encrypted signature

Some API keys use cryptographic signatures as an additional layer of verification. When a user wants to send some data to the API, a digital signature generated by another key can be added to the request. Using cryptography, the API owner can verify that this digital signature matches the data sent.

Symmetric signature and asymmetric signature

Data shared through the API can be signed with an encryption key. The following are the categories of keys:

Symmetric key

This type of key involves performing both data signing and signature verification withoneencryption key. In the symmetric key category, the API key and encryption key are usually generated by the API owner, and the API service must verify the signature with the same encryption key. The main advantage of using a single key is that generating and verifying signatures is faster and requires less computing power. Hash Message Authentication Code (HMAC) is a typical representative of symmetric keys.

Asymmetric key

This type of key involves the use of both private and public keys. There is a difference between the two, but they are related through cryptography. The private key is used to generate the signature, while the public key is used to verify the signature. API keys are generated by the API owner, and private and public key pairs are generated by users. The API owner only needs to use the public key for signature verification, and the private key remains locally encrypted.

Use non The main advantage of symmetric keys is that signature generation and verification keys are independent, resulting in higher security. This allows external systems to verify the signature if it cannot generate the signature. Another advantage is that some asymmetric encryption systems support adding passwords to private keys. RSA key pair is a typical representative.

Are API keys safe?

The function of the API key depends on the user. API keys are similar to passwords and should be treated with caution. Sharing an API key is pretty much the same as sharing a password. Doing so puts the user's account at risk and should not be shared.

API keys can perform powerful operations on the system and are often targeted by cyberattacks. Various operations include requesting personal information or performing financial transactions. In fact, there have been cases where web crawlers have successfully attacked online code databases and stolen API keys.

The consequences of API key theft are serious and may result in significant financial losses. Additionally, some API keys do not expire. Once stolen, as long as the key itself is not invalidated, the attacker can use it as he pleases.

Best practices for using API keys

API keys can access sensitive data and are prone to vulnerabilities, so it is important to use them securely. When using API keys to improve overall security, please follow these best practice guidelines:

1. When possible Frequently change API keys. This means that the current API key should be deleted and a new key created. Generating and deleting API keys is easy for multiple systems. Some systems require users to change their passwords every 30 to 90 days. Similarly, try to change your API keys at this frequency.

2. Use IP whitelist: When creating an API key, make a list of IPs authorized to use the key (i.e. IP whitelist), or make a detailed IP blocking list ( That is, IP blacklist). In this way, even if the API key is stolen, the unrecognized IP will not be able to access it.

3. Use multiple API keys: Having multiple keys and dividing the functions of each key will reduce security risks because security is not determined by a single key with broad permissions. key decision. You can set a different IP whitelist for each key to further reduce security risks.

4. Store API keys securely: Do not store keys in public places or on public computers; do not store them in raw plain text format. Instead, for increased security, encrypt or use an encryption manager to store individual keys separately without inadvertent exposure.

5. Please do not reveal your personal API key. Sharing an API key is much the same as sharing a password. Sharing constitutes granting the other party my verification and authorization rights. When API keys are leaked, they can be stolen and used to hack into personal accounts. The API key can only be used by you and the system that generated it.
   
   

After the API key is leaked, please disable it first to prevent greater losses. If financial losses are caused, please take screenshots of key information related to the incident, contact the relevant units, and report the incident to the police. This is a best practice to increase your chances of recovering lost funds.

Conclusion

API keys provide core authentication and authorization functions for users You must carefully manage and protect your keys. To ensure the safe use of API keys, multi-level and multi-faceted factors should be considered. All in all, API keys should be treated like personal account passwords.

Further reading

• "Universal Security Principles 》

• 5 Common Cryptocurrency Scams and Prevention Strategies