Key derivation functions such as SCrypt and PBKDF2 are used to turn a user's password into a cryptographic key that can be used to encrypt and decrypt data. The two algorithms are designed to be computationally expensive, making brute-force attacks on large lists of passwords difficult.

SCrypt and PBKDF2 differ significantly in the manner in which they generate keys. To generate keys, PBKDF2 applies a cryptographic function (such as SHA-1 or SHA-2) repeatedly to the password and a salt value. If the number of iterations is increased, the process will become more computationally expensive, but it will also take longer to generate a key.

SCrypt, on the other hand, generates keys using a method called "memory-hardness." A large amount of memory is used to perform calculations, making it more challenging for attackers to use specialized hardware (such as GPUs) to perform brute-force attacks. In addition, SCrypt allows users to specify a larger salt value, which increases the number of possible keys that can be generated and makes precomputation attacks more difficult.

Another difference between SCrypt and PBKDF2 is the number of iterations recommended. While PBKDF2 recommends a minimum of 600,000 iterations for adequate security, SCrypt does not make such a recommendation. Instead, it is determined by the cost parameter, which can be adjusted to increase or decrease the computational cost.

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