pEp Foundation

Oberer Graben 4 CH-8400 Winterthur Switzerland hernani.marques@pep.foundation https://pep.foundation/

Ucom Standards Track Solutions GmbH

CH-8046 Zuerich Switzerland +41 44 500 52 44 bernie@ietf.hoeneisen.ch (bernhard.hoeneisen AT ucom.ch) https://ucom.ch/

The pretty Easy privacy (pEp) protocols describe a set of conventions for the automation of operations traditionally seen as barriers to the use and deployment of secure end-to-end interpersonal messaging. These include, but are not limited to, key management, key discovery, and private key handling (including peer-to-peer synchronization of private keys and other user data across devices). pEp also introduces means to verify communication peers and proposes a trust-rating system to denote secure types of communications and signal the privacy level available on a per-user and per-message level. Significantly, the pEp protocols build on already available security formats and message transports (e.g., PGP/MIME), and are written with the intent to be interoperable with already widely-deployed systems in order to facilitate and ease adoption and implementation. This document outlines the general design choices and principles of pEp.

Secure and private communications are vital for many different reasons, and there are particular properties that privacy-preserving protocols need to fulfill in order to best serve users. In particular, has identified and documented important principles such as data minimization, the end-to-end principle, and interoperability as integral properties for access to the Internet for human rights purposes. While (partial) implementations of these concepts are already available, today’s applications widely lack privacy support that ordinary users can easily handle. The pretty Easy privacy (pEp) protocols generally conform with the principles outlined in as a matter of course, and as such can be used to facilitate the adoption and correct usage of secure and private communications technology. The pretty Easy privacy (pEp) protocols are propositions to the Internet community to create software for peers to automatically encrypt, anonymize (where possible), and verify their daily written digital communications. This is achieved by building upon already existing standards and tools and automating each step a user needs to carry out in order to engage in secure end-to-end encrypted communications. Significantly, the pEp protocols describe how do to this without dependence on centralized infrastructures. In particular, pEp proposes automatation of key management, key discovery and synchronization of secret key material by an in-band peer-to-peer approach. To mitigate man-in-the-middle attacks (MITM) by an active adversary, and as the only manual step users carry out in the course of the protocols, the proposed Trustwords mechanism uses natural language representations of two peers’ fingerprints for users to verify their trust in a paired communication channel. [[ Note: The pEp initiators learned from the CryptoParty movement, from which the project emerged, that while step-by-step guides can be helpful for some users to engage in secure end-to-end communications, for the vast majority of users, it is both more effective and more convenient to have these step-by-step procedures put into actual code (as such, following a protocol) and thus automating the initial configuration and whole usage of cryptographic tools.]] The privacy-by-default principles that pEp introduces are in accordance with the perspective outlined in , aiming to provide opportunistic security in the sense of “some protection most of the time”. This is done, however, with the subtle but important difference that when privacy is weighed against security, the choice defaults to privacy. Therefore, data minimization is a primary goal in pEp (e.g., hiding subject lines and headers unnecessary for email transport inside the encrypted payload of a message). The pEp propositions are focused on (but not limited to) written digital communications and cover asynchronous (offline) types of communications like email as well as synchronous (online) types such as chat. pEp’s goal is to bridge different standardized and widely-used communications channels such that users can reach communications partners in the most privacy-enhancing way possible.

While this document describes the general concept of pEp, other documents build on top of this. These documents define other parts of the pEp environment as follows: pEp enhanced applications (e.g., pEp Email ). Helper functions for interaction with peers (e.g., pEp Handshake ) that assist the user with handling and understanding cryptographic parts that he/she needs to be aware of. Helper functions for interactions between a user’s own devices (e.g., pEp Key Sync ) that assist the user to run pEp applications on different devices (such as computer, mobile phone or tables) at the same time. In addition, there are documents that do not directly depend on this one, but provide generic functions needed in pEp, e.g., IANA Registration of Trustword Lists . [[At this stage it is not yet clear to us how many of our implementation details should be part of new RFCs and at which places we can safely refer to already existing RFCs to make clear on which RFCs we already rely.]]

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in . pEp Handshake: The process when Alice – e.g., in-person or via phone – contacts Bob to verify Trustwords (or by fallback: fingerprints) is called pEp Handshake. Trustwords: A scalar-to-word representation of 16-bit numbers (0 to 65535) to natural language words. When doing a Handshake, peers are shown combined Trustwords of both public keys involved to ease the comparison. Trust on First Use (TOFU): cf. Man-in-the-middle attack (MITM): cf.

The pEp protocols are to intended specifically to ensure privacy. There exist cases in the secure communications ecosystem, however, where achieving privacy is in direct contradiction to security though. For instance, in PGP’s Web of Trust, relations between people and trust levels are exposed to the public. Additionally, the privacy of queries is not ensured in such a model when obtaining keys from remote locations. Within the pEp protocols, when security and privacy goals are not in conflict, then the protocols are designed to maximize both security and privacy. However, where they contradict each other, privacy goals are chosen as the default over security considerations. However, in implementing these protocols, it is always the case that users SHOULD have the choice to override the default by corresponding options. In pEp messaging (e.g., when using HTML) content SHALL NOT be obtained from remote locations as this constitutes a privacy breach.

Another important design goal is data minimization, which includes data spareness and hiding all technically concealable information when possible.

The pEp propositions seek to be interoperable with already-widespread message formats and cryptographic protocols and implementations. Seamless communication between users of software which implements pEp and and users of other messaging tools for end-to-end encryption is a design goal. Therefore, pEp abides by the following guidelines: pEp is conservative (strict) in requirements for pEp implementations and how they interact with pEp or other (messaging) implementations. pEp is liberal in accepting input from non-pEp implementations (e.g., it will not produce, but will support the decryption of, PGP/INLINE formats). Where pEp requires divergence from an RFC for privacy reasons (e.g., from OpenPGP propositions as defined in , options SHOULD be implemented to empower the user to override pEp’s defaults.

Messaging and verification processes in pEp are designed to work in a peer-to-peer (P2P) manner, without the involvement of intermediaries. This means there MUST NOT be any pEp-specific central services whatsoever needed for pEp implementations, both in the case of verification of peers and for the actual encryption. However, implementers of pEp MAY provide options for interoperation with providers of centralized infrastructures (e.g., to enable users to communicate with their peers on platforms with vendor lock-in). Trust provided by global Certificate Authorities (e.g., commercial X.509 CAs) SHALL NOT be signaled as trustworthy (cf. ) to users of pEp (e.g., when interoperating with peers using S/MIME) by default.

Implementers of pEp MUST take special care not to confuse users with technical terms, especially those of cryptography (e.g., “keys”, “certificates” or “fingerprints”), unless users explicitly ask for such terms; i.e., advanced settings MAY be available, and in some cases further options may even be required. However, those SHALL NOT be unnecessarily exposed to users of pEp implementations at first glance. The authors believe widespread adoption of end-to-end cryptography is much less of a problem if the users are not confronted with the need to understand cryptography; that is to say, a central goal of pEp of the pEp protocol is that users can just rely on the principles of Privacy by Default. As a consequence, this means that users must not wait for cryptographic tasks (e.g., key generation or public key retrieval) to finish before being able to have their respective message clients ready to communicate. The end result of this is that pEp implementers MUST ensure that the ability to draft, send and receive messages is always preserved – even if that means a message is sent out unencrypted, thus being in accordance with the Opportunistic Security approach outlined in . In turn, pEp implementers MUST ensure that a discernible privacy status is clearly visible to the user – on a per-contact as well as per-message level – so that users easily understand which level of privacy messages are about to be sent with or were received with, respectively. [[Note: We are aware of the fact that usually UX requirements are not part of RFCs. However, in order to encourage massive adoption of secure end-to-end encryption while at the same time avoiding putting users at risk, we believe certain straightforward signaling requirements for users to be a good idea, just as is currently done for already-popular instant messaging services.]]

In pEp, users MUST have the ability to have multiple different identities. pEp users MUST have the option to choose different identities. This allows an Internet user to decide how to reveal himself/herself to the world and is an important element in order to achieve privacy. These different identities MUST NOT be externally correlatable with each other by default. On the other hand, combining different identities when such information is known MUST be supported (alias support).

A key is an OpenPGP-compatible asymmetric key pair. Other formats and temporary symmetrical keys can be generated by Key Mapping. Keys in pEp are identified by the full fingerprint (fpr) of the public key.

A user is a real world human being or a group of human beings. If it is a single human being, it can be called person. A user is identified by a user ID (user_id). The user_id SHOULD be a UUID, it MAY be an arbitrary unique string. The own user can have a user_id like all other users. If it doesn’t, then it has PEP_OWN_USERID “pEp_own_userId” as user_id. A user can have a default key. (cf. )

An identity is a (possibly pseudonymous) representation of a user encapsulating how this user appears in the network. An identity is defined by the mapping of user_id to address. If no user_id is known, it is guessed by mapping of username and address. An identity can have a temporary user_id as a placeholder until a real user_id is known. An identity can have a default key. (cf. ) [[ Note: This is the reason why in current pEp implementations for each (email) account a different key pair is created, which allows a user to retain different identities. ]] In you can find how a pEp identity is defined in the reference implementation of the pEp Engine.

An address is a network address, e.g., an SMTP address or another URI. [[ Note: It might be necessary to introduce further addressing schemes through IETF contributions or IANA registrations, e.g., implementing pEp to bridge to popular messaging services with no URIs defined. ]]

pEp OpenPGP Comments user_id (no concept) ID for a person, i.e. a contact username + address uid comparable only for email fpr fingerprint used as key ID in pEp (no concept) Key ID does not exist in pEp

In order to achieve the goal of widespread adoption of secure communications, key management in pEp MUST be automated.

A pEp implementation MUST ensure that cryptographic keys for every identity configured are available. If a corresponding key pair for the identity of a user is found and said identity fulfills the requirements (e.g., for email, as set out in ), said key pair MUST be reused. Otherwise a new key pair MUST be generated. This may be carried out instantly upon its configuration. On devices with limited processing power (e.g., mobile devices) the key generation may take more time than a user is willing to wait. If this is the case, users SHOULD NOT be stopped from communicating, i.e., the key generation process SHOULD be carried out in the background.

Private keys in pEp implementations MUST always be held on the end user’s device(s): pEp implementers MUST NOT rely on private keys stored in centralized remote locations. This applies even for key storages where the private keys are protected with sufficiently long passphrases. It is considered a violation of pEp’s P2P design principle to rely on centralized infrastructures (cf. ). This also applies for pEp implementations created for applications not residing on a user’s device (e.g., web-based MUAs). In such cases, pEp implementations MUST be done in a way such that the locally-held private key can neither be directly accessed nor leaked to the outside world. [[ Note: It is particularly important that browser add-ons implementing pEp functionality do not obtain their cryptographic code from a centralized (cloud) service, as this must be considered a centralized attack vector allowing for backdoors, negatively impacting privacy. ]] Cf. for a means to synchronize private keys among different devices of the same network address in a secure manner.

Passphrases to protect a user’s private key MUST be supported by pEp implementations, but MUST NOT be enforced by default. That is, if a pEp implementation finds a suitable (i.e., secure enough) cryptographic setup, which uses passphrases, pEp implementations MUST provide a way to unlock the key. However, if a new key pair is generated for a given identity, no passphrase MUST be put in place. The authors assume that the enforcement of secure (i.e., unique and long enough) passphrases would massively reduce the number of pEp users (by hassling them), while providing little to no additional privacy for the common cases of passive monitoring being carried out by corporations or state-level actors.

A private key can be exported from one device for import onto another device. When pEp’s Key Sync (cf. ) is not available or not desired to be used, this is largely a manual process.

As the key is available (cf. ) implementers of pEp are REQUIRED to ensure that the identity’s public key is attached to every outgoing message. However, this MAY be omitted if the peer has previously received a message encrypted with the public key of the sender. The sender’s public key SHOULD be sent encrypted whenever possible, i.e., when a public key of the receiving peer is available. If no encryption key of the recipient is available, the sender’s public key MAY be sent unencrypted. In either case, this approach ensures that messaging clients (e.g., MUAs that at least implement OpenPGP) do not need to have pEp implemented to see a user’s public key. Such peers thus have the chance to (automatically) import the sender’s public key. If there is already a known public key from the sender of a message and it is still valid and not expired, new keys MUST not be used for future communication unless they are signed by the previous key (to avoid a MITM attack). Messages MUST always be encrypted with the receiving peer’s oldest public key, as long as it is valid and not expired. Implementers of pEp SHALL prevent the display of public keys attached to messages (e.g, in email) to the user in order to prevent user confusion by files they are potentially unaware of how to handle. Metadata (e.g., email headers) MUST NOT be added to announce a user’s public key. This is considered unnecessary information leakage as it may affect user privacy, which depends also on a country’s data retention laws. Furthermore, this affects interoperability to existing users (e.g., in the OpenPGP field) that have no notion of such header fields and thus lose the ability to import any such keys distributed this way. It SHOULD, though, be supported to obtain other users’ public keys by extracting them from respective header fields of received messages (in case such approaches get widespread). Keyservers or generally intermediate approaches to obtain a peer’s public key SHALL NOT be used by default. On the other hand, the user MAY be provided with the option to opt-in for remote locations to obtain keys, considering the widespread adoption of such approaches for key distribution. Keys generated or obtained by pEp clients MUST NOT be uploaded to any (intermediate) keystore locations without the user’s explicit consent.

[[ TODO: This section will explain how to deal with keys no longer valid, e.g. if leaked ]]

The following example roughly describes a pEp scenario with a typical initial message flow to demonstrate key exchange and basic trust management: Alice – knowing nothing of Bob – sends a message to Bob. As Alice has no public key from Bob, this message is sent out unencrypted. However, Alice’s public key is automatically attached. Bob can just reply to Alice and – as he received her public key – his messaging client is now able to encrypt the message. At this point the rating for Alice changes to “encrypted” in Bob’s messaging client, which (UX-wise) can be displayed using yellow color (cf. ). Alice receives Bob’s key. As of now Alice is also able to send secure messages to Bob. The rating for Bob changes to “encrypted” (with yellow color) in Alice’s messaging client (cf. ). If Alice and Bob want to prevent man-in-the-middle (MITM) attacks, they can engage in a pEp Handshake comparing their so-called Trustwords (cf. ) and confirm this process if those match. After doing so, their identity rating changes to “encrypted and authenticated” (cf. ), which (UX-wise) can be displayed using a green color. As color code changes for an identity, it is also applied to future messages to/from this identity.

| | | | +-----------------------+ | | Privacy Status for A: | | | *Encrypted* | | +-----------------------+ | | | B sends message to A (Public Key | | attached) / signed and ENCRYPTED | |<------------------------------------------+ | | +-----------------------+ | | Privacy Status for B: | | | *Encrypted* | | +-----------------------+ | | | | A and B sucessfully compare their | | Trustwords over an alternative channel | | (e.g., phone line) | |<-- -- -- -- -- -- -- -- -- -- -- -- -- -->| | | +-----------------------+ +-----------------------+ | Privacy Status for B: | | Privacy Status for A: | | *Trusted* | | *Trusted* | +-----------------------+ +-----------------------+ | | ]]>

For end-users, the most important component of pEp, which MUST be made visible on a per-recipient and per-message level, is the Privacy Status. By colors, symbols and texts a user SHALL immediately understand how private a communication channel with a given peer was or ought to be and a given message was or ought to be.

To establishing trust between peers and to upgrade Privacy Status, pEp defines a handshake, which is specified in . In pEp, Trustwords are used for users to compare the authenticity of peers in order to mitigate MITM attacks. By default, Trustwords MUST be used to represent two peers’ fingerprints of their public keys in pEp implementations. In order to retain compatibility with peers not using pEp implementations (e.g., Mail User Agents (MUAs) with OpenPGP implementations without Trustwords), it is REQUIRED that pEp implementers give the user the choice to show both peers’ fingerprints instead of just their common Trustwords.

pEp includes a Trust Rating system defining Rating and Color Codes to express the Privacy Status of a peer or message . The ratings are labeled, e.g., as “Unencrypted”, “Encrypted”, “Trusted”, “Under Attack”, etc. The Privacy Status in its most general form is expressed with traffic lights semantics (and respective symbols and texts), whereas the three colors yellow, green and red can be applied for any peer or message – like this immediately indicating how secure and trustworthy (and thus private) a communication was or ought to be considered. The pEp Trust Rating system with all its states and respective representations to be followed is outlined in . Note: An example for the rating of communication types, the definition of the data structure by the pEp Engine reference implementation is provided in .

[[ TODO: This section will explain how to deal with the situation when a peer can no longer be trusted, e.g., if a peer’s device is compromised. ]]

An important feature of pEp is to assist the user to run pEp applications on different devices, such as computer, mobile phone or tables, at the same time. Therefore state needs to be synchronized among the different devices.

A decentralized proposition – the pEp Key Synchronization protocol. – defines how pEp users can distribute their private keys among different devices in a secure and trusted manner: this allows Internet users to read their messages across their different devices, when sharing a common address (e.g., the same email account).

[[ TODO: This section will explain how trust and other related state is synchronized among different devices in a secure manner. ]]

pEp aims to be interoperable with existing applications designed to enable privacy, e.g., OpenPGP and S/MIME in email.

In this section a non-exhaustive selection of options is provided.

By default the sender attaches its public key to any outgoing message (cf. ). For situations where a sender wants to ensure that it only attaches a public key to an Internet user which has a pEp implementation, a Passive Mode MUST be available.

Using this option, protection can be disabled generally or selectively. Implementers of pEp MUST provide an option “Disable Protection” to allow a user to disable encryption and signing for: all communication specific contacts specific messages The public key still attached, unless the option “Passive Mode” (cf. ) is activated at the same time.

For internal environments there may be a need to centrally decrypt persons’ messages for archiving or other legal purposes (e.g., in the contexts of public offices and enterprises) by authorized personnel. Therefore, pEp implementers MAY provide an “Extra Keys” option where a message gets encrypted with at least one additional public key. The corresponding secret key(s) are intended to be held (safely and securely), e.g., by CISO staff or other authorized personnel for such an organization. The Extra Keys feature MUST NOT be activated by default for any network address and is intended to be an option only for organizational identities and their corresponding network addresses and accounts – not for addresses used for private purposes. That is, the Extra Keys feature is a feature which SHOULD NOT apply to all identities a user might posses, even if activated.

An option “Blacklist Keys” MUST be provided for an advanced user to be able to disable keys which the user does not want to be used anymore for any new communications. However, the keys SHALL NOT be deleted. It MUST still be possible to verify and decipher past communications.

By attaching the sender’s public key to outgoing messages, Trust on First Use (TOFU) is established. However, this is prone to MITM attacks. Cryptographic key subversion is considered Pervasive Monitoring (PM) according to . Those attacks can be mitigated, if the involved users compare their common Trustwords. This possibility MUST be made easily accessible to pEp users in the user interface implementation. If for compatibility reasons (e.g., with OpenPGP users) no Trustwords can be used, then a comparatively easy way to verify the respective public key fingerprints MUST be implemented. As the use of passphrases for private keys is not advised, devices themselves SHOULD use encryption.

[[ TODO ]]

This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in . The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist. According to , “[…] this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit.”

The following software implementing the pEp protocols (to varying degrees) already exists: pEp for Outlook as add-on for Microsoft Outlook, release pEp for Android (based on a fork of the K9 MUA), release Enigmail/pEp as add-on for Mozilla Thunderbird, release pEp for iOS (implemented in a new MUA), beta pEp for Android, iOS and Outlook are provided by pEp Security, a commercial entity specializing in end-user software implementing pEp while Enigmail/pEp is pursued as community project, supported by the pEp Foundation. All software is available as Free Software and published also in source form.

The pEp Foundation provides a reference implementation of pEp’s core principles and functionalities, which go beyond the documentation status of this Internet-Draft. pEp’s reference implementation is composed of pEp Engine and pEp Adapters (or bindings), alongside with some libraries which pEp Engine relies on to function on certain platforms (like a NetPGP fork we maintain for the iOS platform). The pEp engine is a Free Software library encapsulating implementations of: Key Management Key Management in pEp engine is based on GnuPG key chains (NetPGP on iOS). Keys are stored in an OpenPGP compatible format and can be used for different crypto implementations. Trust Rating pEp engine is sporting a two phase trust rating system. In phase one there is a rating based on channel, crypto and key security named “comm_types”. In phase 2 these are mapped to user representable values which have attached colors to present them in traffic light semantics. Abstract Crypto API The Abstract Crypto API is providing functions to encrypt and decrypt data or full messages without requiring an application programmer to understand the different formats and standards. Message Transports pEp engine will support a growing list of Message Transports to support any widespread text messaging system including email, SMS, XMPP and many more. pEp engine is written in C99 programming language. It is not meant to be used in application code directly. Instead, pEp engine is coming together with a list of software adapters for a variety of programming languages and development environments, which are: pEp COM Server Adapter pEp JNI Adapter pEp JSON Adapter pEp ObjC (and Swift) Adapter pEp Python Adapter pEp Qt Adapter

A selection of code excerpts from the pEp Engine reference implementation (encrypt message, decrypt message, and obtain trustwords) can be found in .

The pEp logo and “pretty Easy privacy” are registered trademarks owned by the non-profit pEp Foundation based in Switzerland. Primarily, we want to ensure the following: Software using the trademarks MUST be backdoor-free. Software using the trademarks MUST be accompanied by a serious (detailed) code audit carried out by a reputable third-party, for any proper release. The pEp Foundation will help to support any community-run (non-commercial) project with the latter, be it organizationally or financially. Through this, the foundation wants to make sure that software using the pEp trademarks is as safe as possible from a security and privacy point of view.

The authors would like to thank the following people who have provided significant contributions to the development of this document: Volker Birk, Krista Bennett, and S. Shelburn. Furthermore, the authors would like to thank the following people who who provided helpful comments and suggestions for this document: Alexey Melnikov, Ben Campbell, Brian Trammell, Bron Gondwana, Daniel Kahn Gillmor, Enrico Tomae, Eric Rescorla, Gabriele Lenzini, Hans-Peter Dittler, Iraklis Symeonidis, Mirja Kuehlewind, Neal Walfield, Pete Resnick, Russ Housley, and Stephen Farrel. This work was initially created by pEp Foundation, and then reviewed and extended with funding by the Internet Society’s Beyond the Net Programme on standardizing pEp.

In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. This Glossary provides definitions, abbreviations, and explanations of terminology for information system security. The 334 pages of entries offer recommendations to improve the comprehensibility of written material that is generated in the Internet Standards Process (RFC 2026). The recommendations follow the principles that such writing should (a) use the same term or definition whenever the same concept is mentioned; (b) use terms in their plainest, dictionary sense; (c) use terms that are already well-established in open publications; and (d) avoid terms that either favor a particular vendor or favor a particular technology or mechanism over other, competing techniques that already exist or could be developed. This memo provides information for the Internet community. This document defines the concept "Opportunistic Security" in the context of communications protocols. Protocol designs based on Opportunistic Security use encryption even when authentication is not available, and use authentication when possible, thereby removing barriers to the widespread use of encryption on the Internet. This document is maintained in order to publish all necessary information needed to develop interoperable applications based on the OpenPGP format. It is not a step-by-step cookbook for writing an application. It describes only the format and methods needed to read, check, generate, and write conforming packets crossing any network. It does not deal with storage and implementation questions. It does, however, discuss implementation issues necessary to avoid security flaws.OpenPGP software uses a combination of strong public-key and symmetric cryptography to provide security services for electronic communications and data storage. These services include confidentiality, key management, authentication, and digital signatures. This document specifies the message formats used in OpenPGP. [STANDARDS-TRACK] Pervasive monitoring is a technical attack that should be mitigated in the design of IETF protocols, where possible. This document describes a simple process that allows authors of Internet-Drafts to record the status of known implementations by including an Implementation Status section. This will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature.This process is not mandatory. Authors of Internet-Drafts are encouraged to consider using the process for their documents, and working groups are invited to think about applying the process to all of their protocol specifications. This document obsoletes RFC 6982, advancing it to a Best Current Practice. This document aims to propose guidelines for human rights considerations, similar to the work done on the guidelines for privacy considerations (RFC 6973). The other parts of this document explain the background of the guidelines and how they were developed.This document is the first milestone in a longer-term research effort. It has been reviewed by the Human Rights Protocol Considerations (HRPC) Research Group and also by individuals from outside the research group. The pretty Easy privacy (pEp) propositions for email are based upon already existing email and encryption formats (i.e., PGP/MIME) and designed to allow for easy implementable and interoperable opportunistic encryption: this ranging from key distribution to mechanisms of subject encryption. The goal of pEp for email is to automatize operations in order to make email encryption usable by a wider range of Internet users, to achieve wide application of confidentiality and privacy practices in the real world. This document defines basic operations of pEp's approach towards email and two PGP/MIME formats (pEp Email Format 1 and 2) to provide certain security guarantees. The proposed operations and formats are targeted to Opportunistic Security scenarios and are already implemented in several applications of pretty Easy privacy (pEp). This document specifies the IANA Registration Guidelines for Trustwords, describes corresponding registration procedures, and provides a guideline for creating Trustword list specifications. Trustwords are common words in a natural language (e.g., English) to which the hexadecimal strings are mapped to. This makes verification processes (e.g., comparison of fingerprints), more practical and less prone to misunderstandings. In many Opportunistic Security scenarios end-to-end encryption is automatized for Internet users. In addition, it is often required to provide the users with easy means to carry out authentication. Depending on several factors, each communication channel to different peers may have a different Privacy Status, e.g., unencrypted, encrypted and encrypted as well as authenticated. Even each message from/to a single peer may have a different Privacy Status. To display the actual Privacy Status to the user, this document defines a Privacy Rating scheme and its mapping to a traffic-light semantics. A Privacy Status is defined on a per-message basis as well as on a per-identity basis. The traffic-light semantics (as color rating) allows for a clear and easily understandable presentation to the user in order to optimize the User Experience (UX). This rating system is most beneficial to Opportunistic Security scenarios and is already implemented in several applications of pretty Easy privacy (pEp). In interpersonal messaging end-to-end encryption means for public key distribution and verification of its authenticity are needed; the latter to prevent man-in-the-middle (MITM) attacks. This document proposes a new method to easily verify a public key is authentic by a Handshake process that allows users to easily authenticate their communication channel. The new method is targeted to Opportunistic Security scenarios and is already implemented in several applications of pretty Easy privacy (pEp). Early draft

This section provides excerpts of the running code from the pEp reference implementation pEp engine (C99 programming language).

How the pEp identity is defined in the data structure (cf. src/pEpEngine.h):

Relational table scheme excerpts (in SQL) used in current pEp implementations, held locally for every pEp installation in a SQLite database:

In the following, is an example for the rating of communication types as defined by a data structure (cf. src/pEpEngine.h ):

The following code excerpts are from the pEp Engine reference implementation, to be found in src/message_api.h. [[ Note: Just a selection; more functionality is available. ]]

Cf. src/message_api.h :

Cf. src/message_api.h :

Cf. src/message_api.h :

Cf. src/message_api.h :

[[ RFC Editor: This section is to be removed before publication ]] draft-birk-pep-03: Major restructure of the document Adapt authors to the actual authors and extend acknowledgement section Added several new sections, e.g., Key Reset, Trust Revoke, Trust Synchronization, Private Key Export / Import, Privacy Considerations (content yet mostly TODO) Added reference to HRPC work / RFC8280 Added text and figure to better explain pEp’s automated Key Exchange and Trust management (basic message flow) Lots of improvement in text and editorial changes draft-birk-pep-02: Move (updated) code to Appendix Add Changelog to Appendix Add Open Issue section to Appendix Fix description of what Extra Keys are Fix Passive Mode description Better explain pEp’s identity system draft-birk-pep-01: Mostly editorial draft-birk-pep-00: Initial version

[[ RFC Editor: This section should be empty and is to be removed before publication ]] References to RFC6973 (Privacy Considerations) Add references to prior work, and what differs here - PEM (cf. RFC1421-1424) Better explain Passive Mode Better explain / illustrate pEp’s identity system Explain Key Mapping (to S/MIME) Add more information to deal with organizational requirements Add text to Key Reset () as well as reference as soon as available Add text to Trust Revoke () as well as reference as soon as available Add text to Trust Synchronization () as well as reference as soon as available Add references to Private Key Export / Import () as soon as reference available Add text to Privacy Considerations ()