Microsoft Technology Licensing, LLC

Muhammad Umar Janjua

Nelly L Porter

Haitao Li

Philip Joseph Hallin

Anthony Paul Penta

Xiaohong Su

Kelvin Sjek Yiu

Anooshiravan Saboori

Bryston Mitsuo Nitta

Vassil Dimitrov Bakalov

Yogesh A Mehta

Anooshiravan Saboor

Maarten Van Horenbeeck

Mihail Frintu

Vassil D Bakalov

The techniques described herein dynamically determine a new signature that is valid and that can be used to verify trust of an object (e.g., a certificate, an executable file, user credentials, etc.). The dynamic determination of the new signature is implemented by an entity performing a trust verification process. The entity can execute a single unified service to establish trust in the object. The dynamic determination, or the ability for an invalid signature to evolve into a newer version that can be trusted, is implemented in response to an invalidity event indicating that the initial signature is no longer valid for trust verification purposes. Example invalidity events can comprise the expiration of a time sensitive signature attribute (e.g., an expired private key), a recently discovered weakness associated with an individual signature attribute (e.g., a key of insufficient length), or a determination that a certificate authority can no longer be trusted.

Evolving a signature during trust verification of an object

In many information security scenarios, a certificate issued by a certificate authority may be presented to a client in order to assert a trust level of a certificated item, such as a message or a web page. However, due to a decentralized structure and incomplete coordination among certificate authorities, the presence and exploitation of security vulnerabilities to issue untrustworthy certificates may be difficult to determine, particularly for an individual client. Presented herein are techniques for advising clients of the reputations of respective certificate authorities by evaluating the certificates issued by such certificate authorities, such as the number and types of domains certified by the certificate; the number and pattern of certificates issued for the domain; and the certification techniques used to issue the certificates. Such evaluation enables a determination of a certificate authority trust level that may be distributed to the clients in a certificate authority trust set.

Advising clients about certificate authority trust

In many information security scenarios, a certificate issued by a certificate authority on behalf of a domain is presented to a client in order to verify the identity of the domain. However, due to a decentralized structure and incomplete coordination among certificate authorities, the presence and exploitation of security vulnerabilities to issue untrustworthy certificates may be difficult for an individual client to determine. Presented herein are techniques for advising clients of the trustworthiness of respective certificate authorities by evaluating the certificates issued by such certificate authorities for suspicious indicators, such as hashcode collisions with other certificates and public key re-use. A trust level may be identified of respective certificate authorities according to the presence or absence of suspicious indicators in the certificates issued by the certificate authority, and a certificate authority trust set may be distributed to advise clients of the trustworthiness of certificates issued by the respective certificate authorities.

Certificate evaluation for certificate authority reputation advising

In many information security scenarios, a certificate issued by a certificating authority may be presented to a client in order to assert a trust level of a certificated item, such as a message or a web page. However, due to a decentralized structure and incomplete coordination among certificating authorities, the presence and exploitation of security vulnerabilities to issue untrustworthy certificates may be difficult to determine, particularly for an individual client. Presented herein are techniques for providing a certificating authority trust service that collects and evaluates certificates submitted to clients by certificating authorities, and advises the clients of a certificating authority trust level for respective certificating authorities (e.g., determined as a consensus of the evaluated certificates issued by the certificating authority). The clients may use a certificating authority trust set distributed by the certificating authority trust service to determine whether to trust a certificate issued from a particular certificating authority.

Certificating authority trust evaluation

A computing device analyzes digital certificates received from various different sites (e.g., accessed via the Internet or other network) in order to automatically detect fraudulent digital certificates. The computing device maintains a record of the digital certificates it receives from these various different sites. A certificate screening service operating remotely from the computing device also accesses these various different sites and maintains a record of the digital certificates that the service receives from these sites. In response to a request to access a target site the computing device receives a current digital certificate from the target site. The computing device determines whether the current digital certificate is genuine or fraudulent based on one or more of previously received digital certificates for the target site, confirmation certificates received from the certificate screening service, and additional characteristics of the digital certificates and/or the target site.

Automatic fraudulent digital certificate detection

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Bellevue, WA, United States of America

Muhammad Umar Janjua