In this article, we'll be discussing Kotlin and PBKDF2 hashing in more depth. We'll cover topics such as what PBKDF2 is, how it works, and how to use it in Kotlin. We'll also provide some code examples to illustrate these concepts.
PBKDF2 (Password-Based Key Derivation Function 2) is a key derivation function that is part of the RSA Laboratories Public-Key Cryptography Standards (PKCS) series. It was published in 2000 as PKCS #5 v2.0.
PBKDF2 is a secure way to derive a key from a password. It takes as input a password, a salt, and a number of iterations. It then runs the password through a hashing function, such as SHA-256, multiple times. The number of iterations is configurable and can be increased to make the computation more expensive and therefore more secure.
The output of PBKDF2 is a byte array that can be used as a key for encryption or other purposes.
The basic idea behind PBKDF2 is to run the password through a hashing function multiple times. This makes it more expensive to compute, and therefore more secure.
PBKDF2 is defined in RFC 2898, which can be found here: https://tools.ietf.org/html/rfc2898.
The algorithm is as follows:
PBKDF2(P, S, c, dkLen)
Input:
P: The password, as a byte array.
S: A salt, as a byte array.
c: The number of iterations to perform.
dkLen: The length of the derived key, in bytes.
Output:
A derived key, as a byte array.
1. Initialize a byte array D with the dkLen bytes set to 0.
2. Set U0 = PRF(P, S || 0x00), where PRF is a pseudorandom function.
3. For i = 1, 2, ..., c:
Set Ui = PRF(P, Ui-1).
Set D = D || Ui.
4. Return D.
Kotlin does not have a built-in library for PBKDF2, but there are several third-party libraries that can be used. In this example, we'll be using the "KotlinPBKDF2" library, which can be found here: https://github.com/ajalt/kotlin-pbkdf2
To use this library, add the following dependency to your build.gradle file:
compile 'com.github.ajalt:kotlin-pbkdf2:1.0.0'
Then, you can use the PBKDF2 function as follows:
val password = "password"
val salt = "salt"
val iterations = 1000
val keyLength = 32
val derivedKey = PBKDF2(password, salt, iterations, keyLength)
In this article, we've discussed Kotlin and PBKDF2 hashing in more depth. We've covered topics such as what PBKDF2 is, how it works, and how to use it in Kotlin. We've also provided some code examples to illustrate these concepts.