SHA-1 Hash Generator

Encrypt any text or file to SHA-1, or try to reverse a known SHA-1 hash with the built-in dictionary. 100% client-side.

About SHA-1

SHA-1 (Secure Hash Algorithm 1) is a cryptographic hash function published by the NSA in 1995. It produces a 160-bit (40-character hexadecimal) digest. SHA-1 is the algorithm Git uses for commit identifiers, and it remains widely deployed in legacy systems. In 2017, researchers demonstrated the first practical SHA-1 collision (the SHAttered attack), so SHA-1 is considered broken for security purposes. It is still acceptable for checksums, deduplication, and non-cryptographic fingerprinting, but for new security-sensitive code use SHA-256 or SHA-3.

How to Use

Encrypt: switch to the Text Input or File Input tab, type / paste text or drop a file, then click Generate SHA-1.
Reverse lookup: switch to the Decrypt (Dictionary) tab, paste the target SHA-1 hash, and start the dictionary attack.
Copy: click the copy icon next to the hash to copy it to your clipboard.

FAQ

Can SHA-1 be decrypted?

Like all cryptographic hashes, SHA-1 cannot be reversed mathematically. The dictionary attack here works by hashing candidate strings and comparing to the target. The built-in top-100 common-password dictionary can crack weak passwords quickly. Paste a larger custom wordlist for broader coverage.

Is SHA-1 still secure?

No — SHA-1 is broken for collision resistance since 2017. Use it only for non-security purposes (checksums, Git object IDs, legacy compatibility). For modern security, use SHA-256, SHA-3, or BLAKE2.

Why does Git use SHA-1?

Git uses SHA-1 to identify commits, trees, and blobs. SHA-1's collision weakness doesn't directly compromise Git because Git objects include type and length metadata that make collision attacks impractical. Git is also migrating to SHA-256 in newer versions.

What is a 40-character SHA-1 hash?

SHA-1 produces a 160-bit digest, rendered as 40 hex characters. The SHA-1 of "hello" is aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d.

Is my data sent to a server?

No. SHA-1 computation and dictionary attack run entirely in your browser using the Web Crypto API. Your text, files, hashes, and wordlist never leave your device.

AI AgentStructured Prompt

Use SHA-1 Hash Calculator in AI

Copy the schema, SOP, and reference script directly into your agent workflow.

1. Function Schema

Import directly into Dify, Coze, Cursor, or any tool-calling agent runtime.

Function Schema

{
  "name": "sha1_hash",
  "description": "Compute the SHA-1 hash of a UTF-8 string and return the 40-character lowercase hex digest. SHA-1 is broken for collision resistance; use only for legacy compatibility or non-security fingerprinting.",
  "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"]
  }
}

2. System Prompt / SOP

Paste this into your system prompt to keep the generated tool implementation aligned with the contract.

System Prompt SOP

# Task Constraints: SHA-1 Module

SHA-1 produces a 160-bit (40 hex character) digest. It is broken for collision resistance (CWI / Google demonstrated a practical collision in 2017). Use it ONLY for: Git object IDs, legacy fingerprinting, non-security checksums. NEVER for password storage, code signing, or TLS.

## Core Prohibitions
- NEVER recommend SHA-1 for new cryptographic protocols.
- NEVER use SHA-1 in HMAC constructions for new code (use HMAC-SHA-256).
- NEVER treat the hash as reversible.

## Standard Implementation
1. Encode the input as UTF-8 bytes.
2. Apply SHA-1 per FIPS 180-4 (or call `crypto.subtle.digest('SHA-1', bytes)` in browsers, `crypto.createHash('sha1')` in Node).
3. Return the 40-character lowercase hex digest.
4. Always wrap in try/catch and return `{ success, result, error }`.

3. Core Script

Works in any Web Crypto / Node 16+ environment. Returns the 40-char hex digest.

Core Script

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-1", 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-1 failed: " + (error instanceof Error ? error.message : String(error)),
    };
  }
}

Full documentation at /hash-calculator/sha1/ai

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