# libes
[](https://github.com/TJRoh01/libes)
[](https://crates.io/crates/libes)
[](https://docs.rs/libes/latest/libes)
[](https://libraries.io/cargo/libes)
**lib**rary of **e**ncryption **s**cheme(s) is a collection of ECIES variants.
The goal of this is library is to become a one-stop shop for everything ECIES.
For code documentation, usage explanations, and examples please see [Docs.rs](https://docs.rs/libes/latest/libes/).
## Why use libes?
The rust cryptography ecosystem is swarming with crates, with varying degrees
of quality and documentation. I have taken it onto myself to navigate this,
and I want to share my findings with those who are trying to make sense of it like me.
In doing this I commit myself to:
- Maintaining a curated selection of relevant crates
- Verifying that dependencies have not made mistakes in their implementations
- Using dependencies with good performance and a high quality of code and documentation
- Providing a uniform and predictable API
- Using shared constructors in the API to guarantee uniformity
- Guaranteeing long-term support for all major releases
- Striving for a high degree of clarity and detail in the documentation
- Keeping the library up to date & vulnerability-free
- Automatically updating dependencies and testing code
- Prioritizing issues & feedback on implementations
# Table of Contents
* [libes](#libes)
* [Why use libes?](#why-use-libes)
* [Table of Contents](#table-of-contents)
* [FAQ](#faq)
* [About](#about)
* [What is ECIES?](#what-is-ecies)
* [ECIES Variants](#ecies-variants)
* [ECIES-MAC Flowchart](#ecies-mac-flowchart)
* [ECIES-AEAD Flowchart](#ecies-aead-flowchart)
* [ECIES-SYN Flowchart](#ecies-syn-flowchart)
* [SemVer](#semver)
* [Release Tracks](#release-tracks)
* [Conditional Compilation](#conditional-compilation)
* [Algorithm support](#algorithm-support)
* [Support icon legend](#support-icon-legend)
* [Elliptic Curve Support Matrix](#elliptic-curve-support-matrix)
* [Encryption Support Matrix](#encryption-support-matrix)
* [Authentication Support Matrix](#authentication-support-matrix)
* [License](#license)
* [Contributing](#contributing)
# FAQ
TBD
# About
## What is ECIES?
ECIES stands for **E**lliptic **C**urve **I**ntegrated **E**ncryption **S**cheme.
It is a type of cryptographic procedure which allows encrypting data
for a specific recipient given only the data to be encrypted and
the recipients public key, everything else is derived from the input
or generated with a
CSPRNG (**C**ryptographically **S**ecure **P**seudo-**R**andom **N**umber **G**enerator).
[Wikipedia](https://en.wikipedia.org/wiki/Integrated_Encryption_Scheme)
[Crypto++](https://www.cryptopp.com/wiki/Elliptic_Curve_Integrated_Encryption_Scheme)
[Practical Cryptography for Developers](https://cryptobook.nakov.com/asymmetric-key-ciphers/ecies-public-key-encryption)
## ECIES Variants
Cryptographic algorithms have evolved over time, and thus have grown into
two distinct ECIES variants as of writing.
Originally, ECIES relied on a key exchange operation, an encryption operation,
and a separate MAC operation.
A MAC (**M**essage **A**uthentication **C**ode) is necessary to provide
**Authenticity** on top of **Confidentiality**. By exploiting vulnerabilities
and/or compromised parameters, encrypted data could potentially be manipulated
to produce a desired output, other than what the sender intended. A MAC can be
used separately from the encrypted data to verify that such manipulation did
not take place.
More recently adopted encryption algorithms like AES-GCM and ChaCha20-Poly1305
are AEAD (**A**uthenticated **E**ncryption with **A**dditional **D**ata) algorithms
which in addition to a ciphertext, also produce an Authentication Tag which serves
the same purpose that a MAC does in this case, but is integrated in the encryption
algorithm itself.
The library and documentation will refer to these two variants as:
- **ECIES-MAC** (Encryption with MAC)
- **ECIES-AEAD** (AEAD Encryption instead of MAC)
Iterating further on ECIES-AEAD, it could be further integrated by **synthesizing**
the IV/Nonce rather than **generating** it randomly. This would eliminate the need
to store & transmit the Nonce, as well as reduce the overhead by one or
two dozen bytes. Because there is already random data in the ephemeral key,
the risk of deriving the same encryption key twice is minimal, and thus it
should be safe to do so. This third variant will be referred to as **ECIES-SYN**.
**DISCLAIMER:** ECIES-SYN is my own idea, which I will only implement for
algorithms that I have done extensive research on to ensure that it is
cryptographically secure to do so. Regardless, I am not a cryptography
researcher and I can not give a guarantee that issues will not arise
in the future. If ECIES-SYN turns out to be useful/popular and resources allow,
I will make sure that it receives a security audit.
## ECIES-MAC Flowchart
Flowchart color coding:
- Red: Encryption
- Green: Elliptic Curve
- Blue: Authentication
```mermaid
graph TB
subgraph Input
RK(Recipient's Public Key)
MSG(Plaintext)
end
subgraph Generate
CSPRNG(CSPRNG)
EK_PUB(Ephemeral Public Key)
EK_PRI(Ephemeral Private Key)
IV(IV/Nonce)
end
subgraph Derive
DER_FN("Derive Shared Secret</br>(e.g. with ECDH -> HKDF-SHA256)</br><- and split ->")
DER_ENC_KEY("Derived Encryption Key")
DER_MAC_KEY("Derived MAC Key")
end
subgraph Process
ENC_FN("Encrypt</br>(e.g. with AES-CBC)")
MAC_FN("MAC</br>(e.g. with HMAC-SHA256)")
end
subgraph Output
ENC_OUT(Ciphertext)
IV_OUT(IV/Nonce)
EK_OUT(Ephemeral Public Key)
MAC_OUT(MAC)
end
CSPRNG --> IV & EK_PRI
EK_PRI --> EK_PUB
EK_PUB --> EK_OUT & MAC_FN
IV --> IV_OUT & MAC_FN & ENC_FN
RK --> DER_FN
EK_PRI --> DER_FN
DER_FN --> DER_ENC_KEY & DER_MAC_KEY
DER_ENC_KEY --> ENC_FN
DER_MAC_KEY --> MAC_FN
MSG --> ENC_FN
ENC_FN --> MAC_FN & ENC_OUT
MAC_FN --> MAC_OUT
EK_PUB --> |Encapsulation| DER_FN
%% Elliptic Curve Key link colorization
linkStyle 2 stroke:#98fb98,stroke-width:2px;
linkStyle 3 stroke:#98fb98,stroke-width:2px;
linkStyle 8 stroke:#98fb98,stroke-width:2px;
linkStyle 9 stroke:#98fb98,stroke-width:2px;
linkStyle 18 stroke:#98fb98,stroke-width:2px;
%% Authentication link colorization
linkStyle 4 stroke:#0096ff,stroke-width:2px;
linkStyle 6 stroke:#0096ff,stroke-width:2px;
linkStyle 11 stroke:#0096ff,stroke-width:2px;
linkStyle 13 stroke:#0096ff,stroke-width:2px;
linkStyle 15 stroke:#0096ff,stroke-width:2px;
linkStyle 17 stroke:#0096ff,stroke-width:2px;
%% Encryption link colorization
linkStyle 7 stroke:#f88379,stroke-width:2px;
linkStyle 10 stroke:#f88379,stroke-width:2px;
linkStyle 12 stroke:#f88379,stroke-width:2px;
linkStyle 14 stroke:#f88379,stroke-width:2px;
linkStyle 16 stroke:#f88379,stroke-width:2px;
```
## ECIES-AEAD Flowchart
Flowchart color coding:
- Red: Encryption
- Green: Elliptic Curve
- Blue: IV/Nonce
```mermaid
graph TB
subgraph Input
RK(Recipient's Public Key)
MSG(Plaintext)
end
subgraph Generate
CSPRNG(CSPRNG)
EK_PUB(Ephemeral Public Key)
EK_PRI(Ephemeral Private Key)
IV(IV/Nonce)
end
subgraph Derive
DER_FN("Derive Shared Secret</br>(e.g. with ECDH -> HKDF-SHA256)")
DER_ENC_KEY("Derived Encryption Key")
end
subgraph Process
ENC_FN("Encrypt using AEAD</br>(e.g. with AES-GCM)")
end
subgraph Output
ENC_OUT(Ciphertext)
IV_OUT(IV/Nonce)
EK_OUT(Ephemeral Public Key)
end
CSPRNG --> EK_PRI & IV
EK_PRI --> EK_PUB
EK_PUB --> EK_OUT
RK --> DER_FN
EK_PRI --> DER_FN
DER_FN --> DER_ENC_KEY
DER_ENC_KEY --> ENC_FN
MSG --> ENC_FN
ENC_FN --> ENC_OUT
IV --> ENC_FN & IV_OUT
EK_PUB --> |Encapsulation| DER_FN
%% Elliptic Curve Key link colorization
linkStyle 2 stroke:#98fb98,stroke-width:2px;
linkStyle 3 stroke:#98fb98,stroke-width:2px;
linkStyle 4 stroke:#98fb98,stroke-width:2px;
linkStyle 5 stroke:#98fb98,stroke-width:2px;
linkStyle 12 stroke:#98fb98,stroke-width:2px;
%% Nonce link colorization
linkStyle 10 stroke:#0096ff,stroke-width:2px;
linkStyle 11 stroke:#0096ff,stroke-width:2px;
%% Encryption link colorization
linkStyle 6 stroke:#f88379,stroke-width:2px;
linkStyle 7 stroke:#f88379,stroke-width:2px;
linkStyle 8 stroke:#f88379,stroke-width:2px;
linkStyle 9 stroke:#f88379,stroke-width:2px;
```
## ECIES-SYN Flowchart
Flowchart color coding:
- Red: Encryption
- Green: Elliptic Curve
- Blue: IV/Nonce
```mermaid
graph TB
subgraph Input
RK(Recipient's Public Key)
MSG(Plaintext)
end
subgraph Generate
CSPRNG(CSPRNG)
EK_PUB(Ephemeral Public Key)
EK_PRI(Ephemeral Private Key)
end
subgraph Derive
DER_FN("Derive Shared Secret</br>(e.g. with ECDH -> HKDF-SHA256)</br><- and split ->")
DER_IV("Derived IV/Nonce")
DER_ENC_KEY("Derived Encryption Key")
end
subgraph Process
ENC_FN("Encrypt using AEAD</br>(e.g. with AES-GCM)")
end
subgraph Output
ENC_OUT(Ciphertext</br>with Authentication Tag)
EK_OUT(Ephemeral Public Key)
end
CSPRNG --> EK_PRI
EK_PRI --> EK_PUB
EK_PUB --> EK_OUT
RK --> DER_FN
EK_PRI --> DER_FN
DER_FN --> DER_ENC_KEY & DER_IV
DER_IV --> ENC_FN
DER_ENC_KEY --> ENC_FN
MSG --> ENC_FN
ENC_FN --> ENC_OUT
EK_PUB --> |Encapsulation| DER_FN
%% Elliptic Curve Key link colorization
linkStyle 1 stroke:#98fb98,stroke-width:2px;
linkStyle 2 stroke:#98fb98,stroke-width:2px;
linkStyle 3 stroke:#98fb98,stroke-width:2px;
linkStyle 4 stroke:#98fb98,stroke-width:2px;
linkStyle 11 stroke:#98fb98,stroke-width:2px;
%% Nonce link colorization
linkStyle 5 stroke:#0096ff,stroke-width:2px;
linkStyle 8 stroke:#0096ff,stroke-width:2px;
%% Encryption link colorization
linkStyle 6 stroke:#f88379,stroke-width:2px;
linkStyle 7 stroke:#f88379,stroke-width:2px;
linkStyle 9 stroke:#f88379,stroke-width:2px;
linkStyle 10 stroke:#f88379,stroke-width:2px;
```
## SemVer
This library respects SemVer, and guarantees decryption backwards compatibility.
This means that data encrypted using library version X.Y.Z can be decrypted
using any superseding library version as long as X is the same.
For example, data encrypted using version 0.5.7 can be decrypted using version
0.5.7 or 0.11.1, but not using versions 1.2.3, 0.5.6, or 0.4.10.
Effort will be made to keep X, the major version, decryption backwards compatible
as well, but no guarantee is given.
## Release Tracks
- v0.1.Z: alpha - initial strcuture
- v0.(2+).Z: beta - adding algorithms
- v1.0.0-pre.W: pre-production - refactoring & memory zeroing implementation
- v1.0.0: initial production - potentially backwards-incompatible refactoring
- V1.(1+).Z: production - wasm support & more
## Conditional Compilation
All algorithm combinations are gated behind features, to reduce how much is
being compiled. Features are named exactly like the algorithm names in the
support matrices (if there are alternative names like P-521 and secp521r1 then
they are aliases, so you can enable either). This library uses traits to implement
appropriate functionality on valid user-defined variants.
**NOTE:** No ECIES variants are available without activating any features,
at minimum one of each feature categories must be activated:
- Elliptic Curve (e.g. x25519)
- Encryption (e.g. AES-GCM)
- Authentication (e.g. ECIES-AEAD or HMAC-SHA256)
**NOTE:** For a ECIES combination to be valid the Elliptic Curve, Encryption,
and Authentication algorithms must all support the same ECIES variant.
- To use ECIES-MAC, all three chosen algorithms need a "🚀" in their respective ECIES-MAC columns
- To use ECIES-AEAD or ECIES-SYN both first two algorithms need a "🚀" in the variant column
# Algorithm support
Matrix entries are of form `Encryption & Decryption` or `Encryption`/`Decryption`
## Support icon legend
- 🚀 Completed
- 🏗️ Development
- 📅 Planned
- 🤔 Planning
- 🚫 Can/Will not implement
## Elliptic Curve Support Matrix
| x25519 | 🚀 | 🚀 | 🚀 |
| ed25519 | 🏗️️ | 🏗️ | 🏗️ |
| K-256 / secp256k1 | 📅 | 📅 | 📅 |
| P-256 / secp256r1 | 📅 | 📅 | 📅 |
| P-384 / secp384r1 | 🤔 | 🤔 | 🤔 |
| P-521 / secp521r1 | 🤔 | 🤔 | 🤔 |
## Encryption Support Matrix
| ChaCha20-Poly1305 | 🚫/🚫 | 🚫/🚫 | 🚫/🚫 |
| XChaCha20-Poly1305 | 🚀 | 🚀 | 🚀 |
| AES-GCM | 📅 | 📅 | 📅 |
## Authentication Support Matrix
| HMAC-SHA256 | 🚀 |
| HMAC-SHA512 | 🤔 |
which when generated using a random function has an unsatisfactory
risk of collision. XChaCha20 uses a 192-bit nonce
where that is no longer an issue.
by implementing decryption for it
# License
Licensed under either of:
- [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
- [MIT license](http://opensource.org/licenses/MIT)
at your option.
# Contributing
All contributions are very appreciated. If you spot a mistake or a vulnerability in
this crate or any of its dependencies please open an issue. Currently, there is no
template for issues or pull requests, but please try to include enough information
to be able to determine what to do without having to ask too many follow-up questions.
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in this project by you, as defined in the Apache-2.0 license,
shall be dual licensed as above, without any additional terms or conditions.