Copyright	(C) Hécate Moonlight 2022
License	BSD-3-Clause
Maintainer	The Haskell Cryptography Group
Stability	Stable
Portability	GHC only
Safe Haskell	Trustworthy
Language	Haskell2010

LibSodium.Bindings.PasswordHashing

Contents

Introduction
Operations
Constants

Description

Synopsis

cryptoPWHash :: Ptr CUChar -> CLLong -> Ptr CChar -> CULLong -> Ptr CUChar -> CULLong -> CSize -> CInt -> IO CInt
cryptoPWHashStr :: Ptr CChar -> Ptr CChar -> CULLong -> CULLong -> CSize -> IO CInt
cryptoPWHashStrVerify :: Ptr CChar -> Ptr CChar -> CULLong -> IO CInt
cryptoPWHashStrNeedsRehash :: Ptr CChar -> CULLong -> CSize -> IO CInt
cryptoPWHashAlgDefault :: CInt
cryptoPWHashAlgArgon2I13 :: CInt
cryptoPWHashAlgArgon2ID13 :: CInt
cryptoPWHashSaltBytes :: CSize
cryptoPWHashPasswdMin :: CSize
cryptoPWHashPasswdMax :: CSize
cryptoPWHashOpsLimitInteractive :: CULLong
cryptoPWHashOpsLimitSensitive :: CULLong
cryptoPWHashOpsLimitModerate :: CULLong
cryptoPWHashOpsLimitMin :: CULLong
cryptoPWHashOpsLimitMax :: CULLong
cryptoPWHashMemLimitModerate :: CSize
cryptoPWHashMemLimitInteractive :: CSize
cryptoPWHashMemLimitSensitive :: CSize
cryptoPWHashMemLimitMin :: CSize
cryptoPWHashMemLimitMax :: CSize
cryptoPWHashBytesMax :: CULLong
cryptoPWHashBytesMin :: CULLong
cryptoPWHashStrBytes :: CSize
cryptoPWHashStrPrefix :: Ptr CChar

Introduction

This modules provides an API that can be used both for key derivation using a low-entropy input and password storage.

Guidelines for choosing the parameters

Start by determining how much memory the function can use. What will be the highest number of threads/processes evaluating the function simultaneously (ideally, no more than 1 per CPU core)? How much physical memory is guaranteed to be available?

Set memlimit to the amount of memory you want to reserve for password hashing.

Then set opslimit to 3 and measure the time it takes to hash a password.

If this is way too long for your application, reduce memlimit, but keep opslimit set to 3.

If the function is so fast that you can afford it to be more computationally intensive without any usability issues, then increase opslimit.

For online use (e.g. logging in on a website), a 1 second computation is likely to be the acceptable maximum.

For interactive use (e.g. a desktop application), a 5 second pause after having entered a password is acceptable if the password doesn't need to be entered more than once per session.

For non-interactive and infrequent use (e.g. restoring an encrypted backup), an even slower computation can be an option.

However, the best defense against brute-force password cracking is to use strong passwords. Libraries such as passwdqc can help enforce this.

Operations

cryptoPWHash Source #

Arguments

:: Ptr CUChar	`out` parameter. It represents the address of a dedicated storage area of `outlen` bytes.
-> CLLong	`outlen` parameter. It is the length of the key derived from the `passwd` parameter. This should be a least `cryptoPWHashBytesMin` and at most `cryptoPWHashBytesMax`.
-> Ptr CChar	`passwd` parameter. It is a pointer to the password that is to be derived.
-> CULLong	`passwdlen` parameter. It is the size of the password.
-> Ptr CUChar	`salt` parameter. It is of a fixed length established by `cryptoPWHashSaltBytes`. It should be unpredictable. `randombytesBuf` is the best way to fill the `cryptoPWHashSaltBytes` of the salt.
-> CULLong	`opslimit` parameter. It represents the maximum amount of computations to perform. Raising this number will make the function require more CPU cycles to compute a key. This number must be between `cryptoPWHashOpsLimitMin` and `cryptoPWHashOpsLimitMax`.
-> CSize	`memlimit` parameter. It is the maximum amount of RAM in bytes that the function will use. This number must be between `cryptoPWHashMemLimitMin` `cryptoPWHashMemLimitMax`
-> CInt	`alg` parameter. It is an identifier for the algorithm to use and should be set to one of the following values: `cryptoPWHashAlgDefault`, `cryptoPWHashAlgArgon2I13` or `cryptoPWHashAlgArgon2ID13`.
-> IO CInt	The return code is 0 on success and -1 if the computation didn't complete, usually because the operating system refused to allocate the amount of requested memory.

This functions derives a key from a password. The computed key is then stored in the out parameter.

See: crypto_pwhash()

Since: 0.0.1.0

cryptoPWHashStr Source #

Arguments

:: Ptr CChar	`out` parameter. It must be of size `cryptoPWHashStrBytes`.
-> Ptr CChar	`passwd` parameter. Points to a password to be stored.
-> CULLong	`passwdlen` parameter. Length of the password.
-> CULLong	`opslimit` parameter. It represents the maximum amount of computations to perform.
-> CSize	`memlimit` parameter. It is the maximum amount of RAM in bytes that the function will use.
-> IO CInt	The function returns 0 on success and -1 if it didn't complete successfully.

This function is used for password storage, like an SQL database. It stores an ASCII-encoded string into its out parameter, which includes:

The result of a memory-hard, CPU-intensive hash function applied to the password passwd of length passwdlen;
The automatically generated salt used for the previous computation;
The other parameters required to verify the password, including the algorithm identifier, its version, opslimit, and memlimit.

The out parameter must be a dedicated storage area that's large enough to hold cryptoPWHashStrBytes bytes, but the actual output string may be shorter.

See: crypto_pwhash_str()

Since: 0.0.1.0

cryptoPWHashStrVerify Source #

Arguments

:: Ptr CChar	`str` parameter. It must be zero-terminated.
-> Ptr CChar	`passwd` parameter.
-> CULLong	`passwdlen` parameter.
-> IO CInt	It returns 0 if the verification succeeds and -1 on error.

This function verifies that the str parameter is a valid password verification string (as generated by cryptoPWHashStr), for a passwd whose length is passwdlen.

See: crypto_pwhash_str_verify()

Since: 0.0.1.0

cryptoPWHashStrNeedsRehash Source #

Arguments

:: Ptr CChar	`str` parameter.
-> CULLong	`opslimit` parameter.
-> CSize	`memlimit` parameter.
-> IO CInt	The function returns 0 if the parameters already match the given ones, and returns 1 on error. In particular, It will return 1 if the string appears to be correct but doesn't match the given parameters. In that situation, applications may want to compute a new hash using the current parameters the next time the user logs in.