# Alphanumeric String Key Generates unique alphanumeric strings of the same length as the input. For example, for the origin value `ABC123`, the output value is a six-character alphanumeric string such as `D24N05`. You can configure the generator to: * Preserve a value prefix. For example, if the origin value always starts with `acct_`, you might want to preserve that in the output value, and only mask the unique part of the identifier. * Only replace numerical characters, and keep other types of characters as is. ## Characteristics


Consistency	Yes, can be made self-consistent.
Linking	No, cannot be linked.
Differential privacy	No
Data-free	No
Allowed for primary keys	Yes
Allowed for unique columns	Yes
Uses format-preserving encryption (FPE)	Yes
Privacy ranking	3 if not consistent 4 if consistent
Generator ID (for the API)	`AlphaNumericPkGenerator`

## How to configure To configure the generator: 1. To preserve a prefix value, in the **Preserve prefix** field, type the prefix string to preserve in the output values.\ \ For example, if you set **Preserve prefix** to `acct_`, then any source values that start with `acct_` will also start with `acct_` in the destination data. 2. To only replace the numerical characters, toggle **Mask digits only** to the on position. 3. Toggle the **Consistency** setting to indicate whether to make the generator self-consistent.\ \ By default, the generator is not consistent. 4. If [Structural data encryption](https://docs.tonic.ai/app/generation/generators-assign-config/generators-data-encryption-config) is enabled, then to use it for this column, in the advanced options section, toggle **Use data encryption process** to the on position.