security 6 min read

Cryptography & Security Best Practices

Understand the differences between hashing, symmetric encryption, and encoding, plus password entropy metrics.

Key Takeaways

Encoding (Base64) is for data transport, NOT security or obfuscation
Cryptographic hashes (SHA-256) are irreversible one-way mathematical digests
Password strength depends primarily on entropy bits rather than arbitrary character rules
HMAC signatures verify both authenticity and data integrity

1. Shannon Entropy & Password Cracking

Entropy measures the unpredictability of a password in bits: E = L * log2(N), where L is the password length and N is the character set size. A 16-character password with letters, digits, and symbols boasts over 100 bits of entropy, requiring billions of years to crack with brute-force computing.

2. The Role of Checksums in File Verification

When downloading software or transferring sensitive archives, compute the SHA-256 or CRC-32 hash of the received file. If the calculated checksum matches the vendor's published digest, you have mathematical proof that the file was not tampered with or corrupted during transit.

Recommended Tools for this Guide

Password Generator

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Barcode Generator

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