How to Generate SHA Hashes, UUID v4 & High-Entropy Passwords
Type or paste any text into the top box to compute SHA-1, SHA-256, SHA-384, and SHA-512 cryptographic digests simultaneously. In the lower section, set your desired bulk UUID count and password length/character classes, inspect the live Shannon entropy calculation in bits, and click Regenerate.
Key Features & Capabilities
- Compute SHA-1, SHA-256, SHA-384, and SHA-512 hexadecimal digests simultaneously using native browser SubtleCrypto
- Generate up to 50 cryptographically random RFC 4122 UUID v4 identifiers in bulk
- Create customizable high-entropy passwords with live Shannon entropy bit-strength calculations
- Execute all hashing and random number generation 100% client-side with zero network transmission
Client-Side Cryptography via the W3C Web Crypto API
Generating passwords, API secrets, or UUID identifiers on a remote server introduces unnecessary network interception and logging risks. This utility uses your browser’s native hardware-backed random number generator (window.crypto.getRandomValues) and SubtleCrypto digest engine (crypto.subtle.digest) to guarantee cryptographic unpredictability with zero external transmission.
| Algorithm / Standard | Bit Length | Hex Output Length | Security Status & Recommended Engineering Use |
|---|---|---|---|
| SHA-1 | 160 bits | 40 hex chars | Legacy checksums & Git commit IDs only (avoid for security signatures) |
| SHA-256 (SHA-2) | 256 bits | 64 hex chars | Industry standard for TLS, JWT HMAC, file integrity & Subresource Integrity |
| SHA-384 (SHA-2) | 384 bits | 96 hex chars | High-security enterprise & government cryptographic suites |
| SHA-512 (SHA-2) | 512 bits | 128 hex chars | Maximum collision resistance on 64-bit processors |
| UUID v4 (RFC 4122) | 122 random bits | 36 chars (8-4-4-4-12) | Distributed database primary keys, idempotency tokens, request trace IDs |
Understanding Password Entropy (Bits of Unpredictability)
Password strength is measured in bits of Shannon entropy: $E = L \times \log_2(N)$, where $L$ is password length and $N$ is the size of the character pool. A 24-character password drawn from uppercase, lowercase, digits, and symbols yields over 148 bits of entropy—making offline brute-force attacks computationally infeasible even against trillions of guesses per second.
Frequently Asked Questions
Can a SHA-256 hash be decrypted back into the original text?
No. Cryptographic hash functions are strictly one-way mathematical operations. They produce a fixed-length fingerprint (digest) from arbitrary input and cannot be reversed.
Why should I use SHA-256 instead of SHA-1?
SHA-1 is vulnerable to practical collision attacks (where two different inputs produce the same hash). Use SHA-256, SHA-384, or SHA-512 for any security-sensitive verification.
Are the generated passwords and UUIDs truly random?
Unlike Math.random() (which is predictable), this tool uses window.crypto.getRandomValues(), which draws entropy directly from your operating system’s cryptographically secure pseudorandom number generator (CSPRNG).