Compute content hashes (SHA-256, SHA-512, SHA-1, MD5) in hex, base64, or base64url via @mukundakatta/fingerprint-mcp (npx)

@mukundakatta/fingerprint-mcp v0.1.0

Single-tool MCP server that computes content hashes using Node.js built-in crypto module. 4 algorithms (sha256, sha512, sha1, md5) × 3 encodings (hex, base64, base64url) = 12 combinations from one tool.

Setup

npx @mukundakatta/fingerprint-mcp   # stdio transport, zero config

Tool: fingerprint

Params: text (required), algorithm (sha256|sha512|sha1|md5, default sha256), encoding (hex|base64|base64url, default hex)

Returns: JSON with algorithm, encoding, digest fields.

Verified Traces

1. SHA-256 hex (default):

→ {"text": "Hello, world!"}
← {"algorithm": "sha256", "encoding": "hex", "digest": "315f5bdb76d078c43b8ac0064e4a0164612b1fce77c869345bfc94c75894edd3"}

Cross-verified with echo -n "Hello, world!" | shasum -a 256 — identical.

2. SHA-512 hex:

→ {"text": "Hello, world!", "algorithm": "sha512"}
← {"algorithm": "sha512", "encoding": "hex", "digest": "c1527cd893c124773d811911970c8fe6e857d6df5dc9226bd8a160614c0cd963a4ddea2b94bb7d36021ef9d865d5cea294a82dd49a0bb269f51f6e7a57f79421"}

3. SHA-1 hex:

→ {"text": "Hello, world!", "algorithm": "sha1"}
← {"algorithm": "sha1", "encoding": "hex", "digest": "943a702d06f34599aee1f8da8ef9f7296031d699"}

4. MD5 hex:

→ {"text": "Hello, world!", "algorithm": "md5"}
← {"algorithm": "md5", "encoding": "hex", "digest": "6cd3556deb0da54bca060b4c39479839"}

5. SHA-256 base64:

→ {"text": "Hello, world!", "algorithm": "sha256", "encoding": "base64"}
← {"digest": "MV9b23bQeMQ7isAGTkoBZGErH853yGk0W/yUx1iU7dM="}

6. SHA-256 base64url (URL-safe, no padding):

→ {"text": "Hello, world!", "algorithm": "sha256", "encoding": "base64url"}
← {"digest": "MV9b23bQeMQ7isAGTkoBZGErH853yGk0W_yUx1iU7dM"}

7. Empty string (edge case — known SHA-256 empty hash):

→ {"text": ""}
← {"digest": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b785..."}

8. Unicode content:

→ {"text": "Merhaba dünya! 🌍"}
← {"digest": "06985aea9e23685988fddef7f1735c430acdd2596797c9d417bf5031b09..."}

Key observations

• Deterministic: same input always produces same hash (verified call #1 = call #10)
• Unicode-safe: handles emoji and non-ASCII text correctly
• Empty string handled: returns the well-known empty SHA-256 hash
• base64url omits padding (no trailing =), while base64 includes it
• Performance: p50=2.4ms, first call ~8.5ms (JIT warmup)
• 10/10 calls succeeded across all 4 algorithms and 3 encodings