# s3kn

> S3 on Linux, macOS, iOS and the JVM. SigV4 checked against all 34 official AWS vectors, presigned URLs on targets with no HTTP engine at all.

Page: https://kotlin.website/s3kn

## Why it exists

The AWS SDK for Kotlin publishes **JVM artefacts only**. On Kotlin/Native the two remaining
options are binding `aws-c-s3` through cinterop — five C libraries and their build, on every
target — or writing the protocol out. This is the second one: a signature and seven HTTP
requests.

## What you get

- **Signature Version 4**, header-based and in the query string, verified against all **34
  official AWS test vectors**, including the four other SDKs skip.
- **S3's own signing rule**, where the path is signed verbatim — no dot segments removed, no
  second round of encoding. Every other AWS service does the opposite.
- **Presigned URLs** for reading and writing, to the seven-day ceiling. Presigning sends
  nothing, so it works on every KMP target, including those with no HTTP engine at all.
- `put`, `get`, `delete`, `head`, streamed both ways, so a five-gigabyte object is never
  held whole.
- Listing as a `Flow` of pages with `encoding-type=url` always on, because an object key may
  hold characters XML 1.0 cannot represent.
- Multipart upload, bounded memory, and an abort on **every** path that can fail — parts
  nobody completes are billed until somebody notices.

## Install

```kotlin
repositories {
    mavenCentral()
    maven("https://reposilite.kotlin.website/snapshots")
}

dependencies {
    implementation("io.github.youndie:s3-client:0.1.0-SNAPSHOT")
    // The engine is yours, and which one exists depends on the target.
    implementation("io.ktor:ktor-client-curl:3.5.2")   // Linux, Windows, macOS
    implementation("io.ktor:ktor-client-darwin:3.5.2") // macOS, and the only choice on iOS
}
```

`s3-sigv4` can be taken on its own if all you need is signing or presigning — it has no HTTP
dependency at all.

## Platform support, stated honestly

`linuxX64` is what this is built for and the only target it is **claimed** to work on: the
whole suite runs there, live tests included. `jvm` runs the same code and the same live tests
in CI. `macosArm64` has had the full suite run against a real server by hand. iOS compiles and
publishes; a device test has never been run.

"It compiles" and "it moved bytes to a real bucket" are different statements, and only one of
them belongs in a support table.