RandomString

Generates a cryptographically secure random string of specified length from a character set using System.Security.Cryptography.RandomNumberGenerator.

Syntax

RandomString(length)
RandomString(length, characterSet)

Parameters

length (number): The length of the string to generate. Must be a non-negative integer.
characterSet (string, optional): The set of characters to select from. When omitted, defaults to alphanumeric characters (a-z, A-Z, 0-9).

Returns

string: A cryptographically secure random string of the specified length

Description

Generates a random string using cryptographically secure randomization, making it suitable for passwords, tokens, authentication codes, and other security-sensitive scenarios.

The default character set includes all alphanumeric characters: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789

You can provide a custom character set for specialized use cases like numeric PINs, hex strings, or restricted character sets.

Uses System.Security.Cryptography.RandomNumberGenerator for cryptographic security rather than pseudo-random generation, ensuring unpredictability suitable for security contexts.

Examples

# Generate an 8-character alphanumeric password
var password = RandomString(8)
# password could be "aB3xK9mP" or similar

# Generate a 16-character secure token
var token = RandomString(16)
# token could be "7hF3kL9mN2pQ5tV8" or similar

# Generate a 6-digit numeric PIN
var pin = RandomString(6, "0123456789")
# pin could be "483921" or similar

# Generate a hexadecimal string (lowercase)
var hex = RandomString(32, "0123456789abcdef")
# hex could be "3a7f2e1d9c4b8f6a2e5d7c9b4f8a6e3d" or similar

# Generate uppercase-only code
var code = RandomString(12, "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
# code could be "H3K9M2P5Q7T8" or similar

# Generate password with special characters
var secure_password = RandomString(16, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*")
# secure_password includes letters, numbers, and special characters

# Generate a session ID
var session_id = RandomString(32)
Data.session_id = session_id
# Creates unpredictable session identifier

# Generate short URL suffix
var url_suffix = RandomString(6, "abcdefghijklmnopqrstuvwxyz0123456789")
var short_url = "https://example.com/" + url_suffix
# short_url could be "https://example.com/k3m9p2" or similar

# Generate API key
var api_key = RandomString(40)
# api_key is a 40-character cryptographically secure string

# Generate temporary filename
var temp_file = "temp_" + RandomString(10) + ".dat"
# temp_file could be "temp_aB3xK9mP4q.dat" or similar

Notes

Uses cryptographically secure random string generation (not pseudo-random)
Default character set is alphanumeric: a-z, A-Z, 0-9 (62 characters)
Custom character sets enable specialized use cases (PINs, hex, etc.)
Length must be a non-negative integer; non-integer or negative values throw an error
Empty or null character sets throw an error
Suitable for security-sensitive scenarios: passwords, tokens, session IDs, API keys
For random integer generation, see RandomInt
For random array element selection, see RandomChoice
Each call produces an independent random string (no seeding required)
Longer strings and larger character sets provide more entropy and security