# Base64Hub — Full LLM Specification & Technical Reference (https://base64hub.online)

> Zero-exfiltration client-side Base64, Base64URL, Hexadecimal (Base16), ITU-R M.1677-1 International Morse Code, NIST FIPS 180-4 SHA-256, and IETF RFC 4122 / RFC 9562 UUID v4 byte telemetry workbench maintained by the Civil Procedure & Cryptographic Standards Desk (Applied Cryptography & Encoding Standards Desk).

## Editorial Policy
- **Content Purpose**: Deterministic client-side byte encoding, radix conversion, signal timing translation, and cryptographic message digest verification modeled directly on published IETF, NIST, IEEE, and ITU-R standards.
- **Target Audience**: Systems engineers, DevSecOps architects, backend API developers, security auditors, and computer science researchers.
- **Verification & Governance**: Every interactive utility and formula is verified by the **Civil Procedure & Cryptographic Standards Desk** (**Applied Cryptography & Encoding Standards Desk**) against official normative test vectors in IETF RFC 4648 §10, NIST FIPS 180-4 Appendix B, IETF RFC 4122 §4.4, and Recommendation ITU-R M.1677-1. Full editorial standards and AI assistance disclosures are published at `https://base64hub.online/about/#editorial-standards`.
- **Zero-Exfiltration Privacy Architecture**: All transformations execute 100% locally inside the user's browser via ECMAScript `TextEncoder`, `TextDecoder`, `Uint8Array`, and `window.crypto.subtle`. Zero payload bytes are ever transmitted to external servers.
- **Statutory Safe Harbor Notice**: This calculation engine models published statutory formulas and regulatory codes for informational and planning purposes only. It does not provide certified legal, medical, veterinary, tax, or engineering advice. For definitive rulings, consult an actively licensed professional in your jurisdiction.

## Site Architecture
```text
/                              — Master Base64 Image Decoder, Byte Codec Workbench & 30-Standard Directory
├── /base64-encoding-tools/    — Data:Image/PNG;Base64 Decoder & RFC 4648 Base64URL Converter
├── /hex-binary-decoders/      — Hexadecimal Decoder: Base16 to ASCII, Binary & Decimal Byte Converter
├── /cryptographic-hash-generators/ — Hash Identifier, FIPS 180-4 SHA-256 Digest & UUID v4 Workbench
├── /uuid-guid-generators/     — UUID v4 & GUID Generator: RFC 4122 CSPRNG 128-Bit Token Minter
├── /morse-cipher-translators/ — Morse Code Decoder: ITU-R M.1677-1 Signal & Cipher Translator
├── /about/                    — Institutional Verification Methodology & Wikidata Knowledge Graph
├── /privacy-policy/           — Zero-Exfiltration Telemetry & Browser-Local Execution Policy
├── /terms-of-service/         — Terms of Service & Statutory Engineering Safe Harbor
├── /sitemap/                  — Dynamic HTML Sitemap & 30-Specification Directory
├── /sitemap-index.xml         — XML Sitemap Index
├── /rss.xml                   — Google Discover & Media RSS 2.0 Feed (1200x675 WebP Enclosures)
├── /llms.txt                  — Concise LLM Overview Manifest
└── /llms-full.txt             — Extended LLM Specification, Test Vectors & WebMCP Reference
```

## Content Schema & Normative Test Vectors (`TC-01`..`TC-05`)

### Route & Specification Schema (`src/data/v4_catalog.json`)
- `id`: Unique slug identifier (e.g., `rfc4648-base64`, `rfc4648-base64url`, `fips180-sha256`, `rfc4122-uuid-v4`, `itur-m1677-morse`)
- `name`: Canonical specification title
- `category`: Taxonomy group (`Radix & Base Encoding`, `Binary & Hex Serialization`, `Cryptographic Hash Digests`, `UUID & Key Provisioning`, `Telegraphy & Classical Ciphers`)
- `standard`: Governing IETF RFC, NIST FIPS, IEEE, or ITU-R document
- `radixOrBits`: Bit quantum or digest width (`6-bit / 24-bit quantum`, `256-bit digest`, `128-bit CSPRNG`)
- `expansionRatio`: Deterministic byte overhead ratio (`1.333x (+33.33%)`, `2.000x (+100%)`, `Fixed 64 Hex Chars`)
- `wikidataId`: Verified Wikidata Knowledge Graph Q-ID (`Q189282`, `Q82828`, `Q474948`, `Q194294`, `Q79897`, `Q1054563`)

### Deterministic Mathematical Test Fixtures
- **TC-01 (IETF RFC 4648 §4 Standard Base64)**:
  - Formula: `L_B64 = 4 * ceil(n / 3)` (`+33.33%` expansion).
  - Vector: `"Hello, Base64!"` (14 UTF-8 bytes) <-> `SGVsbG8sIEJhc2U2NCE=` (20 ASCII chars).
- **TC-02 (IETF RFC 4648 §5 Base64URL)**:
  - Rule: Maps index 62 (`+`) -> `-` (`0x2D`), index 63 (`/`) -> `_` (`0x5F`), strips `=` (`0x3D`) padding.
  - Vector: `[251, 255, 191]` (`0xFBFFBF`) -> `+/+/=` (Standard) -> `-_-_` (Base64URL).
- **TC-03 (IETF RFC 4648 §8 / IEEE 754 Hexadecimal)**:
  - Formula: `V_10 = sum(d_i * 16^i)`, `L_Hex = 2n` (`+100%` expansion).
  - Vector: `48 65 78` -> `Hex` (`0x48='H'`, `0x65='e'`, `0x78='x'`); `0xFF` -> `255` (`11111111` binary).
- **TC-04 (ITU-R M.1677-1 International Morse Code)**:
  - Formula: `T_dah = 3 * T_dit`, `T_char_gap = 3 * T_dit`, `T_word_gap = 7 * T_dit`, `T_dit = 1200 / WPM` ms (50-unit PARIS standard).
  - Vector: `SOS` <-> `... --- ...` (27 dot units).
- **TC-05 (NIST FIPS 180-4 SHA-256 & IETF RFC 4122 UUID v4)**:
  - SHA-256 Identity: `Ch(e,f,g) = (e AND f) XOR (NOT e AND g)`, `Maj(a,b,c) = (a AND b) XOR (a AND c) XOR (b AND c)` mod `2^32`.
  - SHA-256 Vector: `"abc"` -> `ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad`.
  - UUID v4 Regex: `^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$` (122 bits CSPRNG entropy).

## Category Taxonomy & Complete Article/Tool Listing

### 1. Base64, Base32 & Data URI String Converters
- [Base64 Image Decoder: Free Client-Side Data URI & Byte Transcoder](https://base64hub.online/)
- [Data:Image/PNG;Base64 Decoder: RFC 4648 Base64URL Converter](https://base64hub.online/base64-encoding-tools/)

### 2. Hexadecimal, Binary & ASCII Byte Decoders
- [Hexadecimal Decoder: Base16 to ASCII, Binary & Decimal Byte Converter](https://base64hub.online/hex-binary-decoders/)

### 3. Cryptographic Hash, SHA-256 & MD5 Digest Generators
- [Hash Identifier: FIPS 180-4 SHA-256 Digest & UUID v4 Generator](https://base64hub.online/cryptographic-hash-generators/)

### 4. UUID, GUID & Cryptographic Key Generators
- [UUID v4 & GUID Generator: RFC 4122 CSPRNG 128-Bit Token Minter](https://base64hub.online/uuid-guid-generators/)

### 5. Morse Code, Cipher & Signal Translators
- [Morse Code Decoder: ITU-R M.1677-1 Signal & Cipher Translator](https://base64hub.online/morse-cipher-translators/)

### 6. Institutional Verification, Legal & Directory Pages
- [About Base64Hub Methodology & Verification Architecture](https://base64hub.online/about/)
- [HTML Sitemap & 30-Standard Cryptographic Codec Directory](https://base64hub.online/sitemap/)
- [Privacy Policy & Zero-Exfiltration Telemetry Architecture](https://base64hub.online/privacy-policy/)
- [Terms of Service & Statutory Engineering Safe Harbor](https://base64hub.online/terms-of-service/)

## Technical Stack & Dual-Mode WebMCP Interface
- **Static Engine**: Astro 5.x + Tailwind CSS + Self-Hosted Metric-Matched Typography (`Plus Jakarta Sans`, `Inter`, `JetBrains Mono` with `tabular-nums`)
- **Deep-Link Hydration**: Supports `?input=<encoded>&mode=<encode|decode>` and `?payload=<encoded>&mode=<codec>&dir=<encode|decode>` on `DOMContentLoaded`
- **WebMCP Tool Registration**: `navigator.modelContext.registerTool({ name: "base64_crypto_workbench" })` and `window.__V4_CALC__`
- **Structured Data**: JSON-LD `@graph` (`WebSite`, `Organization`, `WebPage`, `SoftwareApplication`, `BreadcrumbList`, `FAQPage`) with Wikidata `sameAs` bindings
- **XML Sitemap**: https://base64hub.online/sitemap-index.xml
- **Media RSS Feed**: https://base64hub.online/rss.xml
- **Concise LLM Index**: https://base64hub.online/llms.txt