Encryption techniques for constraining browser cookies

A system comprising one or more computers and one or more storage devices on which are stored instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations comprising:

• providing, to a component provider process for a digital component provider, an encrypted cookie request that (i) requests encryption of a cookie of the digital component provider and (ii) includes a digital component request identifier for a digital component request with which an encrypted cookie will be sent, the encrypted cookie request for an encrypted cookie configured for inclusion in a request for a digital component for presentation on a webpage, wherein the digital component request identifier is different from digital component request identifiers for different digital component requests transmitted by the one or more computers;
• receiving, from the component provider process, the encrypted cookie generated by encrypting the cookie using the digital component request identifier for the digital component request with which an encrypted cookie will be sent and an encryption key, wherein the encrypted cookie is configured for inclusion in a request for digital components from the digital component provider for presentation on the webpage;
• generating the digital component request for digital components that includes the encrypted cookie and requests identification of a digital component selected for presentation on the webpage using the encrypted cookie;
• and
• transmitting, to a digital component distribution system, the digital component request that includes the encrypted cookie and requests identification of a digital component selected for presentation on the webpage using the encrypted cookie;
• receiving, from the digital component distribution system, the digital component;
• and
• presenting the digital component on the webpage.

A non-transitory computer storage medium encoded with instructions that, when executed by one or more computers, cause the one or more computers to perform operations comprising:

• providing, to a component provider process for a digital component provider, an encrypted cookie request that (i) requests encryption of a cookie of the digital component provider and (ii) includes a digital component request identifier for a digital component request with which an encrypted cookie will be sent, the encrypted cookie request for an encrypted cookie configured for inclusion in a request for a digital component for presentation on a webpage, wherein the digital component request identifier is different from digital component request identifiers for different digital component requests transmitted by the one or more computers;
• receiving, from the component provider process, the encrypted cookie generated by encrypting the cookie using the digital component request identifier for the digital component request with which an encrypted cookie will be sent and an encryption key, wherein the encrypted cookie is configured for inclusion in a request for digital components from the digital component provider for presentation on the webpage;
• generating the digital component request that includes the encrypted cookie and requests identification of a digital component selected for presentation on the webpage using the encrypted cookie;
• and
• transmitting, to a digital component distribution system, the digital component request that includes the encrypted cookie and requests identification of a digital component selected for presentation on the webpage using the encrypted cookie;
• receiving, from the digital component distribution system, the digital component;
• and
• presenting the digital component on the webpage.