https://github.com/lvh/caesium
Modern cryptography (libsodium/NaCl) for Clojure
https://github.com/lvh/caesium
Last synced: about 1 year ago
JSON representation
Modern cryptography (libsodium/NaCl) for Clojure
- Host: GitHub
- URL: https://github.com/lvh/caesium
- Owner: lvh
- License: epl-1.0
- Created: 2014-08-04T15:58:56.000Z (almost 12 years ago)
- Default Branch: master
- Last Pushed: 2023-09-15T19:14:04.000Z (over 2 years ago)
- Last Synced: 2024-10-14T14:11:43.116Z (over 1 year ago)
- Language: Clojure
- Homepage:
- Size: 484 KB
- Stars: 180
- Watchers: 10
- Forks: 28
- Open Issues: 13
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
- Authors: AUTHORS
Awesome Lists containing this project
- awesome-clojure - caesium
README
# caesium
[](http://clojars.org/caesium)
[](https://github.com/lvh/caesium/actions?query=workflow%3Abuild)
[](https://codecov.io/gh/lvh/caesium)
[](https://versions.deps.co/lvh/caesium)
caesium is a modern cryptography library for Clojure. It is a direct
[jnr-ffi][jnr-ffi] binding to [libsodium][libsodium], which in turn is
a more convenient fork of the original [NaCl][nacl] library by
[djb][djb].
[jnr-ffi]: https://github.com/jnr/jnr-ffi
[nacl]: http://nacl.cr.yp.to/.
[djb]: http://cr.yp.to/djb.html
[libsodium]: https://github.com/jedisct1/libsodium
***NOTE:*** Install [libsodium 1.0.18+](https://libsodium.gitbook.io/doc/installation) before trying to use caesium.
## Minimum viable snippet
Here's a sample of how you can use secretbox:
``` clojure
(ns minimum-viable-secretbox
(:require [caesium.crypto.secretbox :as sb]))
(def key (sb/new-key!))
(def plaintext "Hello caesium!")
(def nonce (sb/int->nonce 0))
(def ciphertext (sb/encrypt key nonce (.getBytes plaintext)))
(def roundtrip (String. (sb/decrypt key nonce ciphertext)))
(assert (= plaintext roundtrip))
```
## Documentation
The most important documentation for caesium is actually the
[documentation for libsodium][libsodiumdocs]. Since it's all just relatively
small wrappers around that, everything in it applies.
[libsodiumdocs]: http://doc.libsodium.org
### Password hashing
Here's an example of how you can use pwhash:
``` clojure
(ns pwhash-usage
(:require [caesium.crypto.pwhash :as pwhash]
[caesium.randombytes :as rb]
[caesium.byte-bufs :as bb]
[caesium.util :as u]
[caesium.crypto.secretbox :as sb]))
;; helper function for creating salts from integers. may be useful for deterministic
;; key derivation, incrementing subkeys from 0.
(def int->salt (partial u/n->bytes pwhash/saltbytes))
;; hashing passwords
(def password "example")
(def hashed-password (pwhash/pwhash-str password
pwhash/opslimit-sensitive
pwhash/memlimit-sensitive))
(assert (= 0 (pwhash/pwhash-str-verify hashed-password password)))
;; key derivation
(def salt (rb/randombytes pwhash/saltbytes)) ; changing salt means changed derived key
(def derived-key (pwhash/pwhash sb/keybytes
password
salt
pwhash/opslimit-sensitive
pwhash/memlimit-sensitive
pwhash/alg-default))
(def message (.getBytes "hello, world!"))
(def encrypted-message (sb/encrypt derived-key (sb/int->nonce 0) message))
(def decrypted-message (sb/decrypt derived-key (sb/int->nonce 0) encrypted-message))
(assert (bb/bytes= message decrypted-message))
```
### Usage with Github Actions secrets
Here is how you can create or update a repository secret for GitHub actions:
``` clojure
(require '[caesium.crypto.box])
(require '[clj-http.client :as http])
(require '[jsonista.core :as json])
(import '(java.util Base64))
(def public-key
"The public key of the repository of which you want to create or update a secret"
(let [payload (-> {:request-method :get
:url "https://api.github.com/repos/{owner}/{repo}/actions/secrets/public-key"
:basic-auth ["{user}" "{GITHUB_TOKEN}"]
:headers {"Content-Type" "application/json"
"Accept" "application/vnd.github.v3+json"}}
http/request
:body
json/read-value)
^String encoded-key (get payload "key")]
{:decoded-key (.decode (Base64/getDecoder) (.getBytes encoded-key))
:key-id (get payload "key_id")}))
(let [{:keys [^String decoded-key ^String key-id]} public-key
plaintext "MY_SECRET_VALUE"
cyphertext (caesium.crypto.box/box-seal
(byte-streams/to-byte-array plaintext)
decoded-key)]
(http/request
{:request-method :put
:url "https://api.github.com/repos/{owner}/{repo}/actions/secrets/{MY_SECRET}"
:body (json/write-value-as-string
{:encrypted_value (.encodeToString (Base64/getEncoder) cyphertext)
:key_id key-id})
:basic-auth ["{user}" "{GITHUB_TOKEN}"]
:headers {"Content-Type" "application/json"
"Accept" "application/vnd.github.v3+json"}}))
```
## Differences with other bindings
Instead of making specific claims about specific libraries which may become
outdated, here are a few properties you may care about:
* caesium is written by a cryptographer who has experience binding
cryptographic libraries.
* caesium has continuous integration and a fairly extensive test suite with
very high form/line coverage.
* caesium does not provide magic layers on top of libsodium that prevent you
from writing secure software because of JVM memory semantics, while not
getting in your way if you want the default good-enough behavior.
* caesium uses jnr-ffi pinning correctly; resulting in zero-copy behavior
between JVM and C land at the call site.
* All APIs take `byte[]` and in some cases `ByteBuffer`, never `String`. This
gives you the option of zeroing byte arrays out once you're done. `caesium`
doesn't hide the no-magic C APIs from you; but you have to understand
libsodium to use them. The upside of that is that this library provides the
APIs necessary to use `libsodium` safely; e.g. with locked buffers with
canaries, secure memset, et cetera.
* caesium's APIs match libsodium's behavior. If libsodium hashes a seed to
produce a keypair, caesium will hash a seed to produce a keypair. If
libsodium uses the default output size of a particular hash function,
caesium will use the default output size of that hash function. (These were
at time of writing not true for at least 1 other library).
caesium tries to just give you the libsodium experience from Clojure. C
pseudo-namespaces are mapped to real Clojure namespaces. It usually maps fns to
predictable names; `sodium_crypto_secretbox_open_easy` will be called
`caesium.crypto.secretbox/open-easy`. Formally: take the C pseudo-namespace,
turn it into a real namespace, replace the leading `sodium` with caesium,
replace underscores with dashes. Exceptions where this doesn't work out:
* sometimes, the last part of the C pseudo-namespace is repeated. This happens
for functions that have the same name as a C pseudo-namespace,
e.g. `crypto_generichash` (which is also the pseudo-namespace for
e.g. `crypto_generichash_init`). These would be available in the
`caesium.crypto.generichash` namespace, as `generichash` and `init`. This is
also repeated for some functions where there is a small suffix, e.g. the
function name for the "easy secretbox opener" is `secretbox-easy-open`, not
`easy-open`.
* some functions map to the same underlying C functions, but have different
Java APIs. For example, one of them might cast to `ByteBuffer`, while others
assume byte arrays, while others rely on reflection to call the right
thing. Other pairs of functions might expect you to produce the output
buffer, or manage the output buffer for you. Since these are only JVM-level
differences, these often need different names at the JVM/Clojure
level. (This is always done as a fairly descriptive suffix.)
* functions designed to make a `#define` constant available are accessible as
values, they don't need to be called. For example, you can access the
`crypto_generichash_KEYBYTES_MIN` constant via the `libsodium` `size_t
crypto_generichash_keybytes_min(void);` function, but in caesium, it's just
`caesium.crypto.generichash/keybytes-min` (not a function you have to call).
* some families of functions in libsodium are a consequence of C not
supporting multi-arity functions; e.g. `scalarmult` in libsodium has two
functions: one with the fixed base point and one with an explicit base
point; caesium just has one function with two arities.
* caesium sometimes takes a little artistic license with some of the exposed
names when that makes more sense than the original; generally fns will be
available under both the "official" name and an alias.
## Compatibility
caesium uses [semver](http://semver.org/).
Since this is a security-sensitive library, I will actively remove functions
or APIs that have serious security problems, instead of simply documenting the
problem.
## License
Copyright © the caesium authors (see AUTHORS)
Distributed under the Eclipse Public License either version 1.0 or (at
your option) any later version.