NAME

Crypt::ScryptKDF - Scrypt password based key derivation function

SYNOPSIS

###### creating raw scrypt-based derived key
use Crypt::ScryptKDF qw(scrypt_raw scrypt_hex scrypt_b64);
my $binary_buffer = scrypt_raw($password, $salt, $N, $r, $p, $len);
my $hexadecimal_string = scrypt_hex($password, $salt, $N, $r, $p, $len);
my $base64_string = scrypt_b64($password, $salt, $N, $r, $p, $len);

#or
$key_binary = scrypt_raw($password);
$key_binary = scrypt_raw($password, $salt);
$key_binary = scrypt_raw($password, $N, $r, $p, $len);

#the same applies for
$key_hex = scrypt_hex($password);
$key_hex = scrypt_hex($password, $salt);
$key_hex = scrypt_hex($password, $N, $r, $p, $len);
$key_base64 = scrypt_b64($password);
$key_base64 = scrypt_b64($password, $salt);
$key_base64 = scrypt_b64($password, $N, $r, $p, $len);

###### creating / verifying scrypt-based password hash
use Crypt::ScryptKDF qw(scrypt_hash scrypt_hash_verify random_bytes);

my $hash = scrypt_hash("secret password");
# .. later
die "Invalid password" unless scrypt_hash_verify("secret password", $hash);

#or by specifying Scrypt parameters
my $salt = random_bytes(32);
my $hash = scrypt_hash($password, $salt, $N, $r, $p, $len);
my $hash = scrypt_hash($password, $N, $r, $p, $len);
my $hash = scrypt_hash($password, $salt);

DESCRIPTION

Scrypt is a password-based key derivation function (like for example PBKDF2). Scrypt was designed to be "memory-hard" algorithm in order to make it expensive to perform large scale custom hardware attacks.

It can be used for:

• deriving cryptographic keys from low-entropy password (like PBKDF2)

• creating (+validating) password hashes (like PBKDF2 or Bcrypt)

More details about Scrypt: http://www.tarsnap.com/scrypt/scrypt.pdf and https://tools.ietf.org/html/draft-josefsson-scrypt-kdf-00

IMPORTANT: This module needs a cryptographically strong random number generator. It tries to use one of the following:

• Crypt::OpenSSL::Random - random_bytes()

• Net::SSLeay - RAND_bytes()

• Crypt::Random - makerandom_octet()

• Bytes::Random::Secure - random_bytes()

• As an unsecure fallback it uses built-in rand()

FUNCTIONS

• scrypt_raw

  my $derived_key_raw_bytes = scrypt_raw($password, $salt, $N, $r, $p, $len);
  #  $password - low-entropy secret (bytes)
  #  $salt - random bytes (bytes)
  #  $N - CPU/memory cost (has to be power of 2 and >1); DEFAULT: 2^14
  #  $r - block size parameter; DEFAULT: 8
  #  $p - parallelization parameter; DEFAULT: 1
  #  $len - length of derived key (in bytes); DEFAULT: 32
  #returns:
  #  derived key (raw bytes) of length $len

• scrypt_hex

  Similar to scrypt_raw only the return value is encoded as hexadecimal value.

• scrypt_b64

  Similar to scrypt_raw only the return value is BASE64 encoded.

• scrypt_hash

  my $hash_string = scrypt_hash($password, $salt, $N, $r, $p, $len);
  #  arguments same as scrypt_raw
  #returns:
  #  string with password hash (suitable for storing in DB) e.g.
  #  'SCRYPT:16384:8:1:BK8jkrqgm3BEtMh/g+WGL+k8ZeoAo=:YsEnQWld4UK8EqRZ9JuGbQnnlkXaM='

• scrypt_hash_verify

  my $is_valid = scrypt_hash_verify($password, $hash);
  #  $password - password to be verified
  #  $hash - hash previously created via scrypt_hash
  #returns:
  #  1 (ok) or 0 (fail)

• random_bytes

  my $salt = random_bytes($len);
  #  $len - number of ramdom bytes
  #returns:
  #  $len random octets

COPYRIGHT

Copyright (c) 2013 DCIT, a.s. http://www.dcit.cz / Karel Miko