A data source may be configured to provide usage data including subscriber identifiers and associated information indicative of subscriber device locations and usage. A data warehouse server may be configured to perform operations including: decrypting subscriber identifiers included in usage data received from the data source using a two-way rolling key groups algorithm; re-encrypting the subscriber identifiers decrypted from the usage data to create secure encrypted identifiers using a one-way secured encryption algorithm; and correlating the subscriber identifiers in the decrypted usage data with the corresponding re-encrypted identifiers.