Semantic types

A type declares the semantics of a column so Brume knows what kind of value to generate. Types apply only to the FAKE and MASK strategies — other strategies don’t need them.

Available types

Type	Strategy	Example output (FAKE)	Example output (MASK)
EMAIL	FAKE	alice.smith@example.com	a***@e***.com
FIRST_NAME	FAKE	Alice	A****
LAST_NAME	FAKE	Dupont	D*****
PHONE	FAKE · MASK	08 37 30 90 45 (fr) · (369) 107-2808 (en)	+33 6 ** ** ** 78
ADDRESS	FAKE · MASK	12 rue de la Paix, 75002 Paris	** rue ************, 75002 Paris
IBAN	FAKE · MASK	FR76 3000 6000 0112 3456 7890 189	FR76 **** **** **** **** **** 189
IP_ADDRESS	FAKE · MASK	192.168.1.42	192.168.*.*
DATE	FAKE	1987-11-02	—
JSONB	FAKE	(delegated to json_paths)	—

Notes per type

EMAIL

Generates a syntactically valid email using a fake first name + last name + a safe demonstration TLD. Stable across runs for the same input + secret.

FIRST_NAME · LAST_NAME

Picks from the Datafaker dataset matching the system locale, seeded by HMAC. To get cross-table consistency (the same real person → the same fake first name in users and payments), declare a linked_columns entry.

The dataset holds about 5,000 first names: on a UNIQUE column, the fake carries a uniqueness suffix (Darrell.9f3ac21b04e7d5a6). Same for ADDRESS. See UNIQUE columns and collisions.

PHONE

Generates a phone number in the format of the configured locale. The first digit comes from Datafaker, every other digit is drawn from the HMAC seed — deterministic, and about 81 (en) to 474 (fr) collisions per million values. MASK keeps the international prefix and the last digits, replaces the middle.

Changed in 2.0

Fake phone numbers differ from those produced by 1.x — see Determinism and versions.

ADDRESS

Generates a street, postal code, city. MASK keeps the postal code and city, masks the street number and name.

IBAN

Generates a syntactically valid IBAN (correct country code and check digits). MASK keeps the country / check / last block, masks the rest.

IP_ADDRESS

Generates an IPv4 address. MASK keeps the first two octets (network), masks the last two (host).

DATE

With FAKE, draws a deterministic date — by default a plausible adult birth date between 1935 and 2008. Override the range per column with min_year (inclusive) and max_year (exclusive), both in [1900, 2100]. Works on date and timestamp columns. Refused on a UNIQUE column. To perturb a real date instead of replacing it, use the DATE_SHIFT strategy.

JSONB

Special type: indicates that the column is a JSONB document and Brume should delegate to the json_paths declaration to anonymize specific fields inside the document. See the JSONB recipe.

Choosing a type

Pick the type that matches the column semantics, not its Postgres type. A VARCHAR(255) storing IBANs needs type: IBAN, not “any string”.

If your column doesn’t fit any semantic type but you still want a deterministic fake string, prefer HASH — it gives you a stable opaque value without trying to mimic a real format.

Next

• brume.yml reference — full configuration schema.
• Pseudonymization strategies — what each strategy does.