Custom Charsets & Hashcat Arguments¶

KrakenHashes lets you fine-tune mask attacks with custom character sets and pass additional hashcat arguments on a per-job basis. Both are optional and live in the Create Job dialog (and the admin Preset Job form). This page covers what you can configure and the safety limits that apply.

Custom character sets¶

A mask attack builds candidates from placeholders. Alongside hashcat's built-in sets (?l lowercase, ?u uppercase, ?d digits, ?s symbols, ?a all, ?b raw bytes) you can define up to four custom charsets and reference them in your mask as ?1, ?2, ?3, and ?4.

For example, with charset 1 defined as ?u?l?d, the mask ?1?1?1?1?1?1?1?1 brute-forces all eight-character strings drawn from uppercase + lowercase + digits.

Defining a charset¶

Each of the four slots (labeled Charset 1 (-1) through Charset 4 (-4)) can be filled two ways:

• Inline — type the definition directly. It can mix built-in tokens and literal characters, for example ?u?d (uppercase + digits) or abcdef0123456789.
• Saved charset — pick one from the Saved dropdown next to the slot. The list includes your personal charsets and any global charsets an administrator has published (see Managing saved charsets). A saved charset can be a stored definition or an uploaded .hcchr file.

As you build the mask, a live estimated keyspace chip shows how large the attack will be, along with the size of each referenced charset.

Hex-encoded charsets¶

Toggle Hex-encoded charsets when your charset is expressed as hexadecimal byte pairs — for example 41424344 represents the bytes ABCD. This is useful for non-printable or binary characters. The toggle applies to inline definitions; file-based (.hcchr) charsets are interpreted by hashcat directly and are unaffected. Selecting a saved charset that is marked Hex turns the toggle on automatically. Under the hood this enables hashcat's --hex-charset mode — you do not pass that flag yourself (see blocked flags).

.hcchr charset files¶

For complex character sets you can upload a hashcat charset file (.hcchr) as a saved charset, then select it in a slot. Only .hcchr files are accepted, and the file content is validated on upload. KrakenHashes automatically synchronizes the file to the agents that run your job, so you don't need to distribute it manually.

Managing saved charsets¶

Saved charsets come in two scopes:

In either place you can create an inline charset (name + definition, optionally hex) or upload a .hcchr file. Both scopes appear together in the Saved picker when you build a job's charsets.

Additional hashcat arguments¶

The Additional Hashcat Arguments (Optional) field on a custom job (and on admin preset jobs as additional_args) lets you append extra hashcat flags for that job — for example performance tuning:

-w 4 -O --force

(-w 4 sets the workload profile, -O enables the optimized kernel, --force ignores warnings.)

Limits¶

To keep jobs safe and predictable, the field is validated before the job is created:

• Length: at most 500 characters.
• No shell metacharacters: the characters ; | & ` $ ( ) { } < > \ (and line breaks — both newline and carriage return) are rejected.
• Blocked flags: a set of hashcat flags is rejected because KrakenHashes controls them or they would be unsafe (see below). If you use one, the job is rejected with a message explaining which flag and why.

What you cannot pass¶

Blocked flags fall into these categories:

Stick to performance and tuning flags (workload, optimized kernel, etc.). Flags that control the attack itself, I/O, devices, output, or files are on the blocklist and rejected. The check is a blocklist on the flag name — a flag that isn't on it is passed through to hashcat as-is, so double-check any unfamiliar flag before relying on it.

See also¶

• Jobs & Workflows — creating and configuring jobs
• Wordlist Filtering — another way to tune the candidate space
• Hash Types — supported algorithms