> For the complete documentation index, see [llms.txt](https://alham-rizvi.gitbook.io/alhamrizvi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alham-rizvi.gitbook.io/alhamrizvi/cryptography/hashing/44.-hash-identification.md).

# 44. Hash Identification

## Quick Identification by Length

| Hash Type | Length (hex chars) | Length (bytes) |
| --------- | ------------------ | -------------- |
| MD5       | 32                 | 16             |
| SHA-1     | 40                 | 20             |
| SHA-224   | 56                 | 28             |
| SHA-256   | 64                 | 32             |
| SHA-384   | 96                 | 48             |
| SHA-512   | 128                | 64             |
| NTLM      | 32                 | 16             |
| bcrypt    | 60 (with prefix)   | —              |
| MySQL4    | 16                 | 8              |
| MySQL5    | 40                 | 20             |

## Prefix-Based Identification

| Prefix          | Hash Type           |
| --------------- | ------------------- |
| `$1$`           | MD5-crypt           |
| `$2a$` / `$2b$` | bcrypt              |
| `$5$`           | SHA-256-crypt       |
| `$6$`           | SHA-512-crypt       |
| `$apr1$`        | Apache MD5          |
| `{SHA}`         | Base64 SHA-1 (LDAP) |

## Character Set Clues

* **Hex only** `[0-9a-f]` → MD5, SHA family
* **Base64** `[A-Za-z0-9+/=]` → bcrypt output, some password managers
* **All uppercase** → often Windows hashes (NTLM, LM)

## Tools for Identification

```bash
# hash-identifier (Python tool)
hash-identifier <hash>

# hashid
hashid <hash>
hashid -m <hash>    # show hashcat mode number

# Name-that-hash (modern, color output)
nth --text <hash>

# Online
# https://www.tunnelsup.com/hash-analyzer/
# https://hashes.com/en/tools/hash_identifier
```

## CTF Tips

* Always check **length first** — narrows down candidates instantly
* Check for **salt patterns**: `hash:salt` or `$type$salt$hash`
* Double-hashed values are still the same length (MD5(MD5(x)) = 32 chars)
* Look for context clues: PHP apps → MD5, Linux login → SHA-512-crypt


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