I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written primarily for the benefit of the security area directors. Document editors and WG chairs should treat these comments just like any other last call comments. This document defines a new value for the vCard kind property: application. This value is to be used for vCards that represent software applications. The Security Considerations section of this document states: Use of vCards to represent software applications is not envisioned to introduce security considerations beyond those specified for vCards in general as described in [VCARD]. However, the Security Considerations section of [VCARD] doesn't seem adequate to the task. It merely points out that vCards don't have any security protections and therefore SHOULD be transported over a secure mechanism such as S/MIME or PGP if security is a concern. This advice may be adequate if the vCard is only used to transmit contact information for a person but it's generally not adequate when the vCard contains information about a software application. For example, this draft suggests that the KEY property can be used to convey a public key associated with an application. What a weak way to convey a public key! Will the recipient be able to determine whether the key is accurate? How might the key be revoked if necessary? No provisions are made for this. Other vCard properties such as URL may cause problems if malicious. Without proper security protections, the application vCard kind seems like a great tool for phishing and social engineering. Attackers can forge an email apparently from a trusted party, including an application vCard and instructions to click on it to see something cool. A naive email client may easily decide that clicking on an application vCard should run the application referenced in the vCard or visit the URL in the vCard or whatever. I suggest that the Security Considerations section of the draft be updated to include specific warnings that the contents of an application vCard should be considered untrustworthy and dangerous unless they have been securely delivered from a trustworthy source. Even then, there's a real possibility that the source may have been compromised before the vCard was sent. So information obtained from vCards should not be regarded as ipso facto trustworthy. Software should not act on information contained in a vCard unless there's a strong reason to believe it's accurate. And the KEY property SHOULD NOT be used for an application. Instead, more robust techniques for managing software public keys should be used. Thanks, Steve