Cryptographically secure SHA-256 hash function for AI agents. The current industry standard — used in TLS, JWT, code signing, and password salting.
Import directly into Dify, Coze, Cursor, or any tool-calling agent runtime.
{
"name": "sha256_hash",
"description": "Compute the SHA-256 hash of a UTF-8 string and return the 64-character lowercase hex digest. Cryptographically secure; the industry default for new code.",
"parameters": {
"type": "object",
"properties": {
"input_string": {
"type": "string",
"description": "The raw text to hash. Will be encoded as UTF-8 before hashing."
}
},
"required": ["input_string"]
}
}Paste this into your system prompt to keep the generated tool implementation aligned with the contract.
# Task Constraints: SHA-256 Module
SHA-256 produces a 256-bit (64 hex character) digest. It is the current industry standard for cryptographic hashing and is required for: TLS certificates, JWT signing, OAuth, SSH fingerprints, password salting (with a KDF like Argon2), Bitcoin mining, code signing.
## Core Prohibitions
- NEVER use raw SHA-256 alone for password storage. Always combine with a salt and a slow KDF (Argon2id, scrypt, or PBKDF2-HMAC-SHA256 with high iteration count).
- NEVER truncate SHA-256 to 128 bits for security purposes.
- NEVER recommend MD5 or SHA-1 in new code when SHA-256 is available.
## Standard Implementation
1. Encode the input as UTF-8 bytes (TextEncoder / Buffer).
2. Apply SHA-256 per FIPS 180-4.
3. Return the 64-character lowercase hex digest.
4. Wrap in try/catch and return `{ success, result, error }`.Works in any Web Crypto / Node 16+ environment. For password hashing, chain this with PBKDF2 / Argon2 — do not store the bare SHA-256 of a password.
async function main(args) {
const { input_string } = args;
if (typeof input_string !== "string") {
return { success: false, result: "", error: "input_string must be a string" };
}
try {
const bytes = new TextEncoder().encode(input_string);
const buf = await crypto.subtle.digest("SHA-256", bytes);
const result = Array.from(new Uint8Array(buf))
.map((b) => b.toString(16).padStart(2, "0"))
.join("");
return { success: true, result, error: "" };
} catch (error) {
return {
success: false,
result: "",
error: "SHA-256 failed: " + (error instanceof Error ? error.message : String(error)),
};
}
}