Prior art

To identify the most relevant prior art for US patent 9251531, I will examine the patent citations listed on the USPTO website for patent 9251531.

Most Relevant Prior Art for US Patent 9251531:

To provide a comprehensive analysis of the most relevant prior art for US Patent 9251531, it's necessary to access the full list of "Cited By" references directly from the USPTO patent database for patent 9251531. The provided patent text includes an "Other versions" section listing US20140181927A1, which is a publication of the same application. However, a detailed breakdown of the prior art cited against US9251531B2 is not present in the provided text.

The USPTO's "Enriched Citations" API, mentioned in the search results, would be ideal for this task as it provides bibliographic information, the claims cited against, and relevant sections relied upon by the examiner. Without direct access to this live data or a pre-compiled list of the examiner-cited prior art for US9251531B2, a definitive list of the most relevant prior art cannot be generated with specific claim anticipation details.

However, based on the description within US9251531B2, particularly the "BACKGROUND" section, the patent aims to address issues of fragmentation and insecurity in existing payment systems and the increasing need for secure digital identification as users move away from traditional wallets. Therefore, prior art in the following areas would be highly relevant:

• Secure digital transaction systems: Any systems predating the December 21, 2012 priority date (and March 12, 2013 filing date) that focused on secure digital payments or transactions would be relevant. The patent itself references U.S. patent application Ser. No. 11/851,215, entitled "SYSTEMS, METHODS, AND APPARATUSES FOR SECURE DIGITAL TRANSACTIONS," as describing an RCD payment platform. This specific application, while not explicitly called "prior art" within the '531 patent, is highly relevant as it describes a complementary or foundational technology.
• Electronic credential storage and verification: Prior art dealing with secure methods for storing and verifying electronic identification, loyalty cards, access cards, or other credentials on mobile devices would be pertinent.
• Information code (QR, barcode) based systems for transactions/verification: Any systems using scannable codes for payment, identification, or credential verification prior to the '531 patent's priority date.

To fully fulfill the request, a direct query to the USPTO's patent database for patent 9251531's cited prior art would be necessary.