--- name: "Crypt::PRNG" section: "3pm" platform: "linux" package: "perl-cryptx" version: "0.091-2" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/Crypt::PRNG" --- # Crypt::PRNG(3pm) Cryptographically secure random number generator ## NAME Crypt::PRNG - Cryptographically secure random number generator ## SYNOPSIS ``` ### Functional interface: use Crypt::PRNG qw(random_bytes random_bytes_hex random_bytes_b64 random_bytes_b64u random_string random_string_from rand irand); my $octets = random_bytes(45); my $hex_string = random_bytes_hex(45); my $base64_string = random_bytes_b64(45); my $base64url_string = random_bytes_b64u(45); my $alphanumeric_string = random_string(30); my $string = random_string_from('ACGT', 64); my $floating_point_number_0_to_1 = rand; my $floating_point_number_0_to_88 = rand(88); my $unsigned_32bit_int = irand; ### OO interface: use Crypt::PRNG; my $prng = Crypt::PRNG->new; # defaults to ChaCha20 my $rc4_prng = Crypt::PRNG->new("RC4"); my $seeded_prng = Crypt::PRNG->new("RC4", "some data used for seeding PRNG"); my $octets = $prng->bytes(45); my $hex_string = $prng->bytes_hex(45); my $base64_string = $prng->bytes_b64(45); my $base64url_string = $prng->bytes_b64u(45); my $alphanumeric_string = $prng->string(30); my $string = $prng->string_from('ACGT', 64); my $floating_point_number_0_to_1 = $prng->double; my $floating_point_number_0_to_88 = $prng->double(88); my $unsigned_32bit_int = $prng->int32; ``` ## DESCRIPTION Provides an interface to several pseudo-random number generators (thread-safe and fork-safe). The default algorithm is ChaCha20. ## EXPORT Nothing is exported by default. You can export selected functions: ``` use Crypt::PRNG qw(random_bytes random_string); ``` Or all of them at once: ``` use Crypt::PRNG ':all'; ``` ## FUNCTIONS For all `"random_bytes*"` functions and the corresponding `"bytes*"` methods, `$length` must not be greater than `1000000000`. ### random\_bytes ``` my $octets = random_bytes($length); # $length .. [integer] number of random bytes to generate ``` Returns `$length` random octets as a binary string. ### random\_bytes\_hex ``` my $hex_string = random_bytes_hex($length); # $length .. [integer] number of random bytes (output string will be 2x longer) ``` Returns `$length` random octets encoded as a lowercase hexadecimal string. ### random\_bytes\_b64 ``` my $base64_string = random_bytes_b64($length); # $length .. [integer] number of random bytes to encode ``` Returns `$length` random octets encoded as a Base64 string. ### random\_bytes\_b64u ``` my $base64url_string = random_bytes_b64u($length); # $length .. [integer] number of random bytes to encode ``` Returns `$length` random octets encoded as a Base64 URL-safe string (RFC 4648 section 5). ### random\_string\_from ``` my $string = random_string_from($range, $length); # $range .. [string] alphabet of allowed characters # $length .. [integer] optional, number of characters (DEFAULT: 20) #e.g. my $dna_string = random_string_from("ABCD", 10); ``` Returns a random string of `$length` characters chosen from `$range`. The alphabet must contain between 1 and 65536 characters; longer alphabets return `"undef"`. ### random\_string ``` my $alphanumeric_string = random_string($length); # $length .. [integer] optional, number of characters (DEFAULT: 20) #or my $default_alphanumeric_string = random_string; # default length = 20 ``` Like `"random_string_from"`, but `$range` is fixed to `'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'`. ### rand ``` my $n = rand; #or my $limited_n = rand($limit); # $limit .. [number] optional, upper bound (exclusive) ``` Returns a random floating-point number in the range `"[0,1)"` if called without an argument, or `"[0,$limit)"` if `$limit` is given. If `$limit` is `0`, this behaves as if no limit was given and returns a value in `"[0,1)"`, matching Perl's built-in `"rand"`. ### irand ``` my $i = irand; ``` Returns a random unsigned 32-bit integer in the range `"0 .. 0xFFFFFFFF"`. ## METHODS Unless noted otherwise, assume `$prng` is an existing PRNG object created via `"new"`, for example: ``` my $prng = Crypt::PRNG->new; ``` ### new ``` my $prng = Crypt::PRNG->new; # defaults to ChaCha20 #or my $prng = Crypt::PRNG->new($alg); #or my $prng = Crypt::PRNG->new($alg, $seed); # $alg ... [string] algorithm name: 'ChaCha20' (DEFAULT), 'Fortuna', 'RC4' (legacy; compatibility only), 'Sober128' or 'Yarrow' # $seed ... [binary string] optional, initial entropy for seeding the PRNG ``` If `$seed` is not given, the PRNG is automatically seeded with 40 bytes obtained via libtomcrypt's `rng_get_bytes()` platform RNG logic. If `$seed` is specified it must be non-empty for all algorithms. RC4 is provided for legacy compatibility only, is not recommended for new designs, and requires a seed of at least 5 bytes. ### add\_entropy ``` my $prng = Crypt::PRNG->new; $prng->add_entropy($random_data); #or $prng->add_entropy(); ``` If called without parameter it uses 40 bytes obtained via libtomcrypt's `rng_get_bytes()` platform RNG logic. **Note:** You probably do not need this function. The module seeds itself on initialization and reseeds after fork and thread creation. ### bytes ``` my $octets = $prng->bytes($length); ``` See random\_bytes ### bytes\_hex ``` my $hex_string = $prng->bytes_hex($length); ``` See random\_bytes\_hex ### bytes\_b64 ``` my $base64_string = $prng->bytes_b64($length); ``` See random\_bytes\_b64 ### bytes\_b64u ``` my $base64url_string = $prng->bytes_b64u($length); ``` See random\_bytes\_b64u ### string ``` my $alphanumeric_string = $prng->string($length); #or my $default_alphanumeric_string = $prng->string; # default length = 20 ``` See random\_string ### string\_from ``` my $string = $prng->string_from($range, $length); # default length = 20 ``` See random\_string\_from ### double ``` my $n = $prng->double; #or my $limited_n = $prng->double($limit); ``` See rand ### int32 ``` my $i = $prng->int32; ``` See irand ## SEE ALSO Crypt::PRNG::ChaCha20, Crypt::PRNG::Fortuna, Crypt::PRNG::RC4, Crypt::PRNG::Sober128, Crypt::PRNG::Yarrow For generating random UUIDs see "random\_v4uuid" in Crypt::Misc and "random\_v7uuid" in Crypt::Misc.