F.10 Random Byte Generator for Cryptographic Use

Random Byte Generator for Cryptographic Use

This tutorial introduces rndbytes$(), a built-in SheerPower function that returns a string of cryptographically secure random binary bytes. It's especially useful for cryptographic applications like One-Time Pad (OTP) encryption.

Syntax:

otp_key$ = rndbytes$(length)

Parameters:

length — the number of random binary bytes to generate.

Returns:

A string containing exactly length cryptographically random binary bytes.

Example Use Case:

In this example, we’ll use rndbytes$() to create a one-time pad key for encrypting a message. The encrypted result is then Base64-encoded to make it email-safe.

phrase$ = "meet me in the Philippines" otp_key$ = rndbytes$(len(phrase$)) encrypted$ = xor$(phrase$, otp_key$) for_emailing$ = base64encode$(encrypted$) print 'Original: '; phrase$ print 'Base64 Encrypted: '; for_emailing$ // Now decrypt encrypted_binary$ = base64decode$(for_emailing$) decrypted_phrase$ = xor$(encrypted_binary$, otp_key$) print 'Decrypted: '; decrypted_phrase$

This encrypts the phrase by XORing it with a random byte string of the same length — a method known as One-Time Pad (OTP) encryption.

The result is then encoded in Base64 so it can be safely included in emails or transmitted over text-based channels. To decrypt, simply decode the base64 and then apply xor$() again using the same key.

Step	Value
Original Phrase	"meet me in the Philippines"
rndbytes$(len(phrase$))	e.g., binary: \xA1\x03\xFF\x2C...
xor$(phrase$, otp_key$)	Encrypted binary string
base64encode$(...)	"oQI/LC..." (email-safe output)

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