Node: Up and Running

Crypto

Cryptography is used in lots of places for a variety of tasks. Node uses the OpenSSL library as the basis of its cryptography. This is because OpenSSL is already a well-tested, hardened implementation of cryptographic algorithms. But you have to compile Node with OpenSSL support in order to use the methods in this section.

The cryptograph module enables a number of different tasks. First, it powers the SSL/TLS parts of Node. Second, it contains hashing algorithms such as MD5 or SHA-1 that you might want to use in your application. Third, it allows you to use HMAC.^[12] There are some encryption methods to cipher the data with to ensure it is encrypted. Finally, HMAC contains other public key cryptographic functions to sign data and verify signatures.

Each of the functions that cryptography does is contained within a class (or classes), which we’ll look at in the following sections.

Hashing

Hashes are used for a few important functions, such as obfuscating data in a way that allows it to be validated or providing a small checksum for a much larger piece of data. To use hashes in Node, you should create a Hash object using the factory method crypto.createHash(). This returns a new Hash instance using a specified hashing algorithm. Most popular algorithms are available. The exact ones depend on your version of OpenSSL, but common ones are:

• md5

• sha1

• sha256

• sha512

• ripemd160

These algorithms all have different advantages and disadvantages. MD5, for example, is used in many applications but ...