Implement OTS-CLI utility (#117)

2024-06-18 10:19:43 +00:00 · 2023-10-04 22:27:14 +02:00 · 2023-10-04 22:27:14 +02:00 · 546481dcfc
commit 546481dcfc
parent c5124731f5
20 changed files with 861 additions and 70 deletions
--- a/.github/workflows/test-and-build.yml
+++ b/.github/workflows/test-and-build.yml
@ -50,9 +50,19 @@ jobs:
      - name: Marking workdir safe
        run: git config --global --add safe.directory /__w/ots/ots

-      - name: Lint and test code
+      - name: 'Lint and test code: API'
        run: |
-          go test -v ./...
+          go test -cover -v ./...
+
+      - name: 'Lint and test code: Client'
+        working-directory: ./pkg/client
+        run: |
+          go test -cover -v ./...
+
+      - name: 'Lint and test code: OTS-CLI'
+        working-directory: ./cmd/ots-cli
+        run: |
+          go test -cover -v ./...

      - name: Generate (and validate) translations
        run: make translate
--- a/.gitignore
+++ b/.gitignore
@ -1,3 +1,4 @@
+.build
 customize.yaml
 frontend/api.html
 frontend/app.css
--- a/3
+++ b/3
@ -23,8 +23,7 @@ generate-inner:
 	node ./ci/build.mjs

 publish: download_libs generate-inner generate-apidocs
-	curl -sSLo golang.sh https://raw.githubusercontent.com/Luzifer/github-publish/master/golang.sh
-	bash golang.sh
+	bash ./ci/build.sh

 translate:
 	cd ci/translate && go run .
--- a/ci/build.sh
+++ b/ci/build.sh
@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+osarch=(
+  darwin/amd64
+  darwin/arm64
+  linux/amd64
+  linux/arm
+  linux/arm64
+  windows/amd64
+)
+
+function go_package() {
+  cd "${4}"
+
+  local outname="${3}"
+  [[ $1 == windows ]] && outname="${3}.exe"
+
+  log "=> Building ${3} for ${1}/${2}..."
+  CGO_ENABLED=0 GOARCH=$2 GOOS=$1 go build \
+    -ldflags "-s -w -X main.version=${version}" \
+    -mod=readonly \
+    -trimpath \
+    -o "${outname}"
+
+  if [[ $1 == linux ]]; then
+    log "=> Packging ${3} as ${3}_${1}_${2}.tgz..."
+    tar -czf "${builddir}/${3}_${1}_${2}.tgz" "${outname}"
+  else
+    log "=> Packging ${3} as ${3}_${1}_${2}.zip..."
+    zip "${builddir}/${3}_${1}_${2}.zip" "${outname}"
+  fi
+
+  rm "${outname}"
+}
+
+function go_package_all() {
+  for oa in "${osarch[@]}"; do
+    local os=$(cut -d / -f 1 <<<"${oa}")
+    local arch=$(cut -d / -f 2 <<<"${oa}")
+    (go_package "${os}" "${arch}" "${1}" "${2}")
+  done
+}
+
+function log() {
+  echo "[$(date +%H:%M:%S)] $@" >&2
+}
+
+root=$(pwd)
+builddir="${root}/.build"
+version="$(git describe --tags --always || echo dev)"
+
+log "Building version ${version}..."
+
+log "Resetting output directory..."
+rm -rf "${builddir}"
+mkdir -p "${builddir}"
+
+log "Building API-Server..."
+go_package_all "ots" "."
+
+log "Building OTS-CLI..."
+go_package_all "ots-cli" "./cmd/ots-cli"
+
+log "Generating SHA256SUMS file..."
+(cd "${builddir}" && sha256sum * | tee SHA256SUMS)
--- a/cli_create.sh
+++ b/cli_create.sh
@ -1,38 +0,0 @@
-#!/bin/bash
-set -euo pipefail
-
-: ${INSTANCE:=https://ots.fyi} # Where to reach the API of the instance (omit trailing slash)
-
-deps=(curl jq)
-for cmd in "${deps[@]}"; do
-  which ${cmd} >/dev/null || {
-    echo "'${cmd}' util is required for this script"
-    exit 1
-  }
-done
-
-# Get secret from CLI argument
-SECRET=${1:-}
-[[ -n $SECRET ]] || {
-  echo "Usage: $0 'secret to share'"
-  exit 1
-}
-
-# Generate a random 20 character password
-pass=$(cat /dev/urandom | tr -dc 'a-zA-Z0-9' | head -c 20 || true)
-
-# Encrypt the secret
-ciphertext=$(echo "${SECRET}" | openssl aes-256-cbc -base64 -A -pass "pass:${pass}" -iter 300000 -md sha512 2>/dev/null)
-
-# Create a secret and extract the secret ID
-id=$(
-  curl -sSf \
-    -X POST \
-    -H 'content-type: application/json' \
-    -d "$(jq --arg secret "${ciphertext}" -cn '{"secret": $secret}')" \
-    "${INSTANCE}/api/create" |
-    jq -r '.secret_id'
-)
-
-# Display URL to user
-echo -e "Secret is now available at:\n${INSTANCE}/#${id}%7C${pass}"
--- a/cli_get.sh
+++ b/cli_get.sh
@ -1,28 +0,0 @@
-#!/bin/bash
-set -euo pipefail
-
-deps=(curl jq)
-for cmd in "${deps[@]}"; do
-  which ${cmd} >/dev/null || {
-    echo "'${cmd}' util is required for this script"
-    exit 1
-  }
-done
-
-# Get URL from CLI argument
-url="${1:-}"
-[[ -n $url ]] || {
-  echo "Usage: $0 'URL to get the secret'"
-  exit 1
-}
-# normalize url and extract parts
-url="${url/|/%7C}"
-host="${url%%/\#*}"
-idpass="${url##*\#}"
-pass="${idpass##*\%7C}"
-id="${idpass%%\%7C*}"
-geturl="${host}/api/get/${id}"
-
-# fetch secret and decrypt to STDOUT
-curl -sSf "${geturl}" | jq -r ".secret" |
-  openssl aes-256-cbc -base64 -A -pass "pass:${pass}" -iter 300000 -md sha512 -d
--- a/cmd/ots-cli/.gitignore
+++ b/cmd/ots-cli/.gitignore
@ -0,0 +1 @@
+ots-cli
--- a/cmd/ots-cli/cmd_create.go
+++ b/cmd/ots-cli/cmd_create.go
@ -0,0 +1,105 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"mime"
+	"os"
+	"path"
+
+	"github.com/Luzifer/ots/pkg/client"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+var createCmd = &cobra.Command{
+	Use:     "create [-f file]... [--instance url] [--secret-from file]",
+	Short:   "Create a new encrypted secret in the given OTS instance",
+	Long:    "",
+	Example: `echo "I'm a very secret secret" | ots-cli create`,
+	Args:    cobra.NoArgs,
+	RunE:    createRunE,
+}
+
+func init() {
+	createCmd.Flags().Duration("expire", 0, "When to expire the secret (0 to use server-default)")
+	createCmd.Flags().String("instance", "https://ots.fyi/", "Instance to create the secret with")
+	createCmd.Flags().StringSliceP("file", "f", nil, "File(s) to attach to the secret")
+	createCmd.Flags().String("secret-from", "-", `File to read the secret content from ("-" for STDIN)`)
+	rootCmd.AddCommand(createCmd)
+}
+
+func createRunE(cmd *cobra.Command, _ []string) error {
+	var secret client.Secret
+
+	// Read the secret content
+	logrus.Info("reading secret content...")
+	secretSourceName, err := cmd.Flags().GetString("secret-from")
+	if err != nil {
+		return fmt.Errorf("getting secret-from flag: %w", err)
+	}
+
+	var secretSource io.Reader
+	if secretSourceName == "-" {
+		secretSource = os.Stdin
+	} else {
+		f, err := os.Open(secretSourceName) //#nosec:G304 // Opening user specified file is intended
+		if err != nil {
+			return fmt.Errorf("opening secret-from file: %w", err)
+		}
+		defer f.Close() //nolint:errcheck // The file will be force-closed by program exit
+		secretSource = f
+	}
+
+	secretContent, err := io.ReadAll(secretSource)
+	if err != nil {
+		return fmt.Errorf("reading secret content: %w", err)
+	}
+	secret.Secret = string(secretContent)
+
+	// Attach any file given
+	files, err := cmd.Flags().GetStringSlice("file")
+	if err != nil {
+		return fmt.Errorf("getting file flag: %w", err)
+	}
+	for _, f := range files {
+		logrus.WithField("file", f).Info("attaching file...")
+		content, err := os.ReadFile(f) //#nosec:G304 // Opening user specified file is intended
+		if err != nil {
+			return fmt.Errorf("reading attachment %q: %w", f, err)
+		}
+
+		secret.Attachments = append(secret.Attachments, client.SecretAttachment{
+			Name:    f,
+			Type:    mime.TypeByExtension(path.Ext(f)),
+			Content: content,
+		})
+	}
+
+	// Create the secret
+	logrus.Info("creating the secret...")
+	instanceURL, err := cmd.Flags().GetString("instance")
+	if err != nil {
+		return fmt.Errorf("getting instance flag: %w", err)
+	}
+
+	expire, err := cmd.Flags().GetDuration("expire")
+	if err != nil {
+		return fmt.Errorf("getting expire flag: %w", err)
+	}
+
+	secretURL, expiresAt, err := client.Create(instanceURL, secret, expire)
+	if err != nil {
+		return fmt.Errorf("creating secret: %w", err)
+	}
+
+	// Tell them where to find the secret
+	if expiresAt.IsZero() {
+		logrus.Info("secret created, see URL below")
+	} else {
+		logrus.WithField("expires-at", expiresAt).Info("secret created, see URL below")
+	}
+	fmt.Println(secretURL) //nolint:forbidigo // Output intended for STDOUT
+
+	return nil
+}
--- a/cmd/ots-cli/cmd_fetch.go
+++ b/cmd/ots-cli/cmd_fetch.go
@ -0,0 +1,96 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path"
+	"strings"
+
+	"github.com/Luzifer/ots/pkg/client"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+const storeFileMode = 0o600 // We assume the attached file to be a secret
+
+var fetchCmd = &cobra.Command{
+	Use:   "fetch url",
+	Short: "Retrieves a secret from the instance by its URL",
+	Long:  "",
+	Args:  cobra.ExactArgs(1),
+	RunE:  fetchRunE,
+}
+
+func init() {
+	fetchCmd.Flags().String("file-dir", ".", "Where to put files attached to the secret")
+	rootCmd.AddCommand(fetchCmd)
+}
+
+func checkDirWritable(dir string) error {
+	tmpFile := path.Join(dir, ".ots-cli.tmp")
+	if err := os.WriteFile(tmpFile, []byte(""), storeFileMode); err != nil {
+		return fmt.Errorf("writing tmp-file: %w", err)
+	}
+	defer os.Remove(tmpFile) //nolint:errcheck // We don't really care
+
+	return nil
+}
+
+func fetchRunE(cmd *cobra.Command, args []string) error {
+	fileDir, err := cmd.Flags().GetString("file-dir")
+	if err != nil {
+		return fmt.Errorf("getting file-dir parameter: %w", err)
+	}
+
+	// First lets check whether we potentially can write files
+	if err := checkDirWritable(fileDir); err != nil {
+		return fmt.Errorf("checking for directory write: %w", err)
+	}
+
+	logrus.Info("fetching secret...")
+	secret, err := client.Fetch(args[0])
+	if err != nil {
+		return fmt.Errorf("fetching secret")
+	}
+
+	for _, f := range secret.Attachments {
+		logrus.WithField("file", f.Name).Info("storing file...")
+		if err = storeAttachment(fileDir, f); err != nil {
+			return fmt.Errorf("saving file to disk: %w", err)
+		}
+	}
+
+	fmt.Println(secret.Secret) //nolint:forbidigo // Output intended for STDOUT
+
+	return nil
+}
+
+func storeAttachment(dir string, f client.SecretAttachment) error {
+	// First lets find a free file name to save the file as
+	var (
+		fileNameFragments = strings.SplitN(f.Name, ".", 2) //nolint:gomnd
+		i                 int
+		storeName         = path.Join(dir, f.Name)
+		storeNameTpl      string
+	)
+
+	if len(fileNameFragments) == 1 {
+		storeNameTpl = fmt.Sprintf("%s (%%d)", fileNameFragments[0])
+	} else {
+		storeNameTpl = fmt.Sprintf("%s (%%d).%s", fileNameFragments[0], fileNameFragments[1])
+	}
+
+	for _, err := os.Stat(storeName); !errors.Is(err, fs.ErrNotExist); _, err = os.Stat(storeName) {
+		i++
+		storeName = fmt.Sprintf(storeNameTpl, i)
+	}
+
+	// So we finally found a filename we can use
+	if err := os.WriteFile(storeName, f.Content, storeFileMode); err != nil {
+		return fmt.Errorf("writing file: %w", err)
+	}
+
+	return nil
+}
--- a/cmd/ots-cli/cmd_root.go
+++ b/cmd/ots-cli/cmd_root.go
@ -0,0 +1,32 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+var rootCmd = &cobra.Command{
+	Short:             "Utility to interact with encrypted secrets in an OTS instance",
+	PersistentPreRunE: rootPersistentPreRunE,
+}
+
+func init() {
+	rootCmd.PersistentFlags().String("log-level", "info", "Level to use for logging (trace, debug, info, warn, error, fatal)")
+}
+
+func rootPersistentPreRunE(cmd *cobra.Command, _ []string) error {
+	sll, err := cmd.Flags().GetString("log-level")
+	if err != nil {
+		return fmt.Errorf("getting log-level: %w", err)
+	}
+
+	ll, err := logrus.ParseLevel(sll)
+	if err != nil {
+		return fmt.Errorf("parsing log-level: %w", err)
+	}
+	logrus.SetLevel(ll)
+
+	return nil
+}
--- a/cmd/ots-cli/go.mod
+++ b/cmd/ots-cli/go.mod
@ -0,0 +1,19 @@
+module github.com/Luzifer/ots/cmd/ots-cli
+
+go 1.21.1
+
+replace github.com/Luzifer/ots/pkg/client => ../../pkg/client
+
+require (
+	github.com/Luzifer/ots/pkg/client v0.0.0-00010101000000-000000000000
+	github.com/sirupsen/logrus v1.9.3
+	github.com/spf13/cobra v1.7.0
+)
+
+require (
+	github.com/Luzifer/go-openssl/v4 v4.2.1 // indirect
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	golang.org/x/crypto v0.12.0 // indirect
+	golang.org/x/sys v0.11.0 // indirect
+)
--- a/cmd/ots-cli/go.sum
+++ b/cmd/ots-cli/go.sum
@ -0,0 +1,30 @@
+github.com/Luzifer/go-openssl/v4 v4.2.1 h1:0+/gaQ5TcBhGmVqGrfyA21eujlbbaNwj0VlOA3nh4ts=
+github.com/Luzifer/go-openssl/v4 v4.2.1/go.mod h1:CZZZWY0buCtkxrkqDPQYigC4Kn55UuO97TEoV+hwz2s=
+github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
+github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/spf13/cobra v1.7.0 h1:hyqWnYt1ZQShIddO5kBpj3vu05/++x6tJ6dg8EC572I=
+github.com/spf13/cobra v1.7.0/go.mod h1:uLxZILRyS/50WlhOIKD7W6V5bgeIt+4sICxh6uRMrb0=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+golang.org/x/crypto v0.12.0 h1:tFM/ta59kqch6LlvYnPa0yx5a83cL2nHflFhYKvv9Yk=
+golang.org/x/crypto v0.12.0/go.mod h1:NF0Gs7EO5K4qLn+Ylc+fih8BSTeIjAP05siRnAh98yw=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.11.0 h1:eG7RXZHdqOJ1i+0lgLgCpSXAp6M3LYlAo6osgSi0xOM=
+golang.org/x/sys v0.11.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
--- a/cmd/ots-cli/main.go
+++ b/cmd/ots-cli/main.go
@ -0,0 +1,9 @@
+package main
+
+import "os"
+
+func main() {
+	if err := rootCmd.Execute(); err != nil {
+		os.Exit(1)
+	}
+}
--- a/docs/OTSMeta-format.md
+++ b/docs/OTSMeta-format.md
@ -0,0 +1,56 @@
+> OTS uses two different formats to store secrets under the hood. Both of them can be read and written by the frontend implementation as well as by the `ots-cli` application.
+
+## Simple Format
+
+The simple format is the format used by OTS since day one and is the, well, most simple one. It only consists of the secret encrypted using OpenSSL AES-256-CBC compatible encryption. This format is preferred for backwards compatibility when no other reasons require the use of the OTS-Meta format.
+
+```console
+# openssl enc -aes-256-cbc -pbkdf2 -md sha512 -iter 300000 -pass pass:12345678 -a -A <<<"I'm a secret"
+U2FsdGVkX19G3GuIw3LGM0PVQmavPU/LnWvJhcLeYvs=
+
+# curl -H 'Content-Type: application/json' -d '{"secret": "U2FsdGVkX19G3GuIw3LGM0PVQmavPU/LnWvJhcLeYvs="}' https://ots.fyi/api/create
+{"success":true,"expires_at":"2023-10-11T19:45:01.315587714Z","secret_id":"bbd53ec5-8ee9-4df5-a630-9561313a348a"}
+
+# ots-cli fetch "https://ots.fyi/#bbd53ec5-8ee9-4df5-a630-9561313a348a%7C12345678"
+INFO[0000] fetching secret...
+I'm a secret
+```
+
+## OTSMeta Format
+
+The OTSMeta format was first introduced in `v1.9.0` of OTS together with the possibility to attach files to the secret. It contains structured data with a banner to differentiate between a simple JSON shared through OTS and the OTSMeta format. The OTSMeta structure itself is a simple JSON document containing a secret and a number of attachments having their contents base64 encoded:
+
+```json
+{
+  "secret": "I'm a secret",
+  "attachments": [
+    {
+      "name": "file.txt",
+      "type": "text/plain",
+      "data": "SSdtIGZpbGUgY29udGVudAo="
+    }
+  ]
+}
+```
+
+This structure is prefixed with the Banner `OTSMeta` and then shared the same way as a simple secret would be:
+
+```console
+# ots-cli create -f file.txt <<<"I'm a secret"
+INFO[0000] reading secret content...
+INFO[0000] attaching file...                             file=file.txt
+INFO[0000] creating the secret...
+INFO[0000] secret created, see URL below                 expires-at="2023-10-11 19:52:30.816059504 +0000 UTC"
+https://ots.fyi/#6a6be08c-97d7-4970-a202-5bb6964460d8%7CwNUURZ0LRrQAhaczdZfj
+
+# curl -sS https://ots.fyi/api/get/6a6be08c-97d7-4970-a202-5bb6964460d8 | jq -r .secret >/tmp/secret.bin
+# openssl enc -aes-256-cbc -pbkdf2 -md sha512 -iter 300000 -pass pass:wNUURZ0LRrQAhaczdZfj -a -A -d </tmp/secret.bin
+OTSMeta{"secret":"I'm a secret\n","attachments":[{"name":"file.txt","type":"text/plain; charset=utf-8","data":"SSdtIGZpbGUgY29udGVudAo="}]}
+```
+
+Of course it's also possible to share a simple secret in OTSMeta format but the recommended way would be to omit the OTSMeta wrapping:
+```
+OTSMeta{"secret":"I'm a secret"}
+```
+
+When programmatically reading secrets you therefore need to check whether the secret starts with `OTSMeta` and decode the remaining as a JSON document and if it does not just use all the content as the secret.
--- a/pkg/client/client.go
+++ b/pkg/client/client.go
@ -0,0 +1,199 @@
+// Package client implements a client library for OTS supporting the
+// OTSMeta content format for file upload support
+package client
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"crypto/sha512"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/Luzifer/go-openssl/v4"
+)
+
+// HTTPClient defines the client to use for create and fetch requests
+// and can be overwritten to provide authentication
+var HTTPClient = http.DefaultClient
+
+// KeyDerivationFunc defines the key derivation algorithm used in OTS
+// to derive the key / iv from the password for encryption. You only
+// should change this if you are running an OTS instance with modified
+// parameters.
+//
+// The corresponding settings are found in `/src/crypto.js` in the OTS
+// source code.
+var KeyDerivationFunc = openssl.NewPBKDF2Generator(sha512.New, 300000) //nolint:gomnd // that's the definition
+
+// PasswordLength defines the length of the generated encryption password
+var PasswordLength = 20
+
+// RequestTimeout defines how long the request to the OTS instance for
+// create and fetch may take
+var RequestTimeout = 5 * time.Second
+
+// UserAgent defines the user-agent to send when interacting with an
+// OTS instance. When using this library please set this to something
+// the operator of the instance can determine your client from and
+// provide an URL to useful information about your tool.
+var UserAgent = "ots-client/1.x +https://github.com/Luzifer/ots"
+
+// Create serializes the secret and creates a new secret on the
+// instance given by its URL.
+//
+// The given URL should point to the frontend of the instance. Do not
+// include the API paths, they are added automatically. For the
+// expireIn parameter zero value can be used to use server-default.
+//
+// So for OTS.fyi you'd use `New("https://ots.fyi/")`
+func Create(instanceURL string, secret Secret, expireIn time.Duration) (string, time.Time, error) {
+	u, err := url.Parse(instanceURL)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("parsing instance URL: %w", err)
+	}
+
+	pass, err := genPass()
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("generating password: %w", err)
+	}
+
+	data, err := secret.serialize(pass)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("serializing data: %w", err)
+	}
+
+	body := new(bytes.Buffer)
+	if err = json.NewEncoder(body).Encode(struct {
+		Secret string `json:"secret"`
+	}{Secret: string(data)}); err != nil {
+		return "", time.Time{}, fmt.Errorf("encoding request payload: %w", err)
+	}
+
+	createURL := u.JoinPath(strings.Join([]string{".", "api", "create"}, "/"))
+	ctx, cancel := context.WithTimeout(context.Background(), RequestTimeout)
+	defer cancel()
+
+	if expireIn > time.Second {
+		createURL.RawQuery = url.Values{
+			"expire": []string{strconv.Itoa(int(expireIn / time.Second))},
+		}.Encode()
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, createURL.String(), body)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("creating request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", UserAgent)
+
+	resp, err := HTTPClient.Do(req)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("executing request: %w", err)
+	}
+	defer resp.Body.Close() //nolint:errcheck // possible leaked-fd, lib should not log, potential short-lived leak
+
+	if resp.StatusCode != http.StatusCreated {
+		respBody, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return "", time.Time{}, fmt.Errorf("unexpected HTTP status %d", resp.StatusCode)
+		}
+		return "", time.Time{}, fmt.Errorf("unexpected HTTP status %d (%s)", resp.StatusCode, respBody)
+	}
+
+	var payload struct {
+		ExpiresAt time.Time `json:"expires_at"`
+		SecretID  string    `json:"secret_id"`
+		Success   bool      `json:"success"`
+	}
+
+	if err = json.NewDecoder(resp.Body).Decode(&payload); err != nil {
+		return "", time.Time{}, fmt.Errorf("decoding response: %w", err)
+	}
+
+	u.Fragment = strings.Join([]string{payload.SecretID, pass}, "|")
+
+	return u.String(), payload.ExpiresAt, nil
+}
+
+// Fetch retrieves a secret by its given URL. The URL given must
+// include the fragment (part after the `#`) with the secret ID and
+// the encryption passphrase.
+//
+// The object returned will always be an OTSMeta object even in case
+// the secret is a plain secret without attachments.
+func Fetch(secretURL string) (s Secret, err error) {
+	u, err := url.Parse(secretURL)
+	if err != nil {
+		return s, fmt.Errorf("parsing secret URL: %w", err)
+	}
+
+	fragment, err := url.QueryUnescape(u.Fragment)
+	if err != nil {
+		return s, fmt.Errorf("unescaping fragment: %w", err)
+	}
+	fragmentParts := strings.SplitN(fragment, "|", 2) //nolint:gomnd
+
+	fetchURL := u.JoinPath(strings.Join([]string{".", "api", "get", fragmentParts[0]}, "/")).String()
+	ctx, cancel := context.WithTimeout(context.Background(), RequestTimeout)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fetchURL, nil)
+	if err != nil {
+		return s, fmt.Errorf("creating request: %w", err)
+	}
+	req.Header.Set("User-Agent", UserAgent)
+
+	resp, err := HTTPClient.Do(req)
+	if err != nil {
+		return s, fmt.Errorf("executing request: %w", err)
+	}
+	defer resp.Body.Close() //nolint:errcheck // possible leaked-fd, lib should not log, potential short-lived leak
+
+	if resp.StatusCode != http.StatusOK {
+		return s, fmt.Errorf("unexpected HTTP status %d", resp.StatusCode)
+	}
+
+	var payload struct {
+		Secret string `json:"secret"`
+	}
+
+	if err = json.NewDecoder(resp.Body).Decode(&payload); err != nil {
+		return s, fmt.Errorf("decoding response body: %w", err)
+	}
+
+	if err = s.read([]byte(payload.Secret), fragmentParts[1]); err != nil {
+		return s, fmt.Errorf("decoding secret: %w", err)
+	}
+
+	return s, nil
+}
+
+func genPass() (string, error) {
+	var (
+		charSet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+		pass    = make([]byte, PasswordLength)
+
+		n   int
+		err error
+	)
+
+	for n < PasswordLength {
+		n, err = rand.Read(pass)
+		if err != nil {
+			return "", fmt.Errorf("reading random data: %w", err)
+		}
+	}
+
+	for i := 0; i < PasswordLength; i++ {
+		pass[i] = charSet[int(pass[i])%len(charSet)]
+	}
+
+	return string(pass), nil
+}
--- a/pkg/client/client_test.go
+++ b/pkg/client/client_test.go
@ -0,0 +1,38 @@
+package client
+
+import (
+	"regexp"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGeneratePassword(t *testing.T) {
+	pass, err := genPass()
+	require.NoError(t, err)
+
+	assert.Len(t, pass, PasswordLength)
+	assert.Regexp(t, regexp.MustCompile(`^[0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ]+$`), pass)
+}
+
+func TestIntegration(t *testing.T) {
+	s := Secret{
+		Secret: "I'm a secret!",
+		Attachments: []SecretAttachment{{
+			Name:    "secret.txt",
+			Type:    "text/plain",
+			Content: []byte("I'm a very secret file.\n"),
+		}},
+	}
+
+	secretURL, _, err := Create("https://ots.fyi/", s, time.Minute)
+	require.NoError(t, err)
+	assert.Regexp(t, regexp.MustCompile(`^https://ots.fyi/#[0-9a-f-]+%7C[0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ]+$`), secretURL)
+
+	apiSecret, err := Fetch(secretURL)
+	require.NoError(t, err)
+
+	assert.Equal(t, s, apiSecret)
+}
--- a/pkg/client/go.mod
+++ b/pkg/client/go.mod
@ -0,0 +1,15 @@
+module github.com/Luzifer/ots/pkg/client
+
+go 1.21.1
+
+require (
+	github.com/Luzifer/go-openssl/v4 v4.2.1
+	github.com/stretchr/testify v1.8.4
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	golang.org/x/crypto v0.12.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
--- a/pkg/client/go.sum
+++ b/pkg/client/go.sum
@ -0,0 +1,14 @@
+github.com/Luzifer/go-openssl/v4 v4.2.1 h1:0+/gaQ5TcBhGmVqGrfyA21eujlbbaNwj0VlOA3nh4ts=
+github.com/Luzifer/go-openssl/v4 v4.2.1/go.mod h1:CZZZWY0buCtkxrkqDPQYigC4Kn55UuO97TEoV+hwz2s=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+golang.org/x/crypto v0.12.0 h1:tFM/ta59kqch6LlvYnPa0yx5a83cL2nHflFhYKvv9Yk=
+golang.org/x/crypto v0.12.0/go.mod h1:NF0Gs7EO5K4qLn+Ylc+fih8BSTeIjAP05siRnAh98yw=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
--- a/pkg/client/otsMeta.go
+++ b/pkg/client/otsMeta.go
@ -0,0 +1,92 @@
+package client
+
+import (
+	"bytes"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+
+	"github.com/Luzifer/go-openssl/v4"
+)
+
+var metaMarker = []byte("OTSMeta")
+
+type (
+	// Secret represents a secret parsed from / prepared for
+	// serialization to the OTS API
+	Secret struct {
+		Secret      string             `json:"secret"`
+		Attachments []SecretAttachment `json:"attachments,omitempty"`
+	}
+
+	// SecretAttachment represents a file attached to a Secret. The Data
+	// property must be the plain content (binary / text / ...) of the
+	// file to attach. The base64 en-/decoding is done transparently.
+	// The Name is the name of the file shown to the user (so ideally
+	// should be the file-name on the source system). The Type should
+	// contain the mime time of the file or an empty string.
+	SecretAttachment struct {
+		Name    string `json:"name"`
+		Type    string `json:"type"`
+		Data    string `json:"data"`
+		Content []byte `json:"-"`
+	}
+)
+
+func (o *Secret) read(data []byte, passphrase string) (err error) {
+	if passphrase != "" {
+		if data, err = openssl.New().DecryptBytes(passphrase, data, KeyDerivationFunc); err != nil {
+			return fmt.Errorf("decrypting data: %w", err)
+		}
+	}
+
+	if !bytes.HasPrefix(data, metaMarker) {
+		// We have a simple secret, makes less effort for us
+		o.Secret = string(data)
+		return nil
+	}
+
+	if err = json.Unmarshal(data[len(metaMarker):], o); err != nil {
+		return fmt.Errorf("decoding JSON payload: %w", err)
+	}
+
+	for i := range o.Attachments {
+		o.Attachments[i].Content, err = base64.StdEncoding.DecodeString(o.Attachments[i].Data)
+		if err != nil {
+			return fmt.Errorf("decoding attachment %d: %w", i, err)
+		}
+	}
+
+	return nil
+}
+
+func (o Secret) serialize(passphrase string) ([]byte, error) {
+	var data []byte
+
+	if len(o.Attachments) == 0 {
+		// No attachments? No problem, we create a classic simple secret
+		data = []byte(o.Secret)
+	} else {
+		for i := range o.Attachments {
+			o.Attachments[i].Data = base64.StdEncoding.EncodeToString(o.Attachments[i].Content)
+		}
+
+		j, err := json.Marshal(o)
+		if err != nil {
+			return nil, fmt.Errorf("encoding JSON payload: %w", err)
+		}
+
+		data = append(metaMarker, j...) //nolint:gocritic // :shrug:
+	}
+
+	if passphrase == "" {
+		// No encryption requested
+		return data, nil
+	}
+
+	out, err := openssl.New().EncryptBytes(passphrase, data, KeyDerivationFunc)
+	if err != nil {
+		return nil, fmt.Errorf("encrypting data: %w", err)
+	}
+	return out, nil
+}
--- a/pkg/client/otsMeta_test.go
+++ b/pkg/client/otsMeta_test.go
@ -0,0 +1,75 @@
+package client
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestReadOTSMeta(t *testing.T) {
+	var (
+		//#nosec:G101 // Hardcoded credentials, just test-data
+		secretData = "U2FsdGVkX1+7kNgAK57O/qdbsukK3OchMyMyE1tWzVJVlc9f9bkp8iaFHbwR7Q3b8tWhWmPAcfeOoBJH2zl1iNbIHWsmMKu3+pzE5wTE4wl31dOboV8LgsMChBFL5RQpda0iGku32BcB4tYEyb2VHcM/kkXNJh9lW1vRyiNx0iF8pe05JUkkmJJrnzIKC+/efZEfF2YX7fOaBC1+8AAhlg=="
+		//#nosec:G101 // Hardcoded credentials, just test-data
+		pass = "IKeiXsyGuVWdMUG8Fj3R"
+		s    Secret
+	)
+
+	err := s.read([]byte(secretData), pass)
+	require.NoError(t, err)
+
+	assert.Equal(t, Secret{
+		Secret: "I'm a secret!",
+		Attachments: []SecretAttachment{{
+			Name:    "secret.txt",
+			Type:    "text/plain",
+			Data:    "SSdtIGEgdmVyeSBzZWNyZXQgZmlsZS4K",
+			Content: []byte("I'm a very secret file.\n"),
+		}},
+	}, s)
+}
+
+func TestReadSimpleSecret(t *testing.T) {
+	var (
+		//#nosec:G101 // Hardcoded credentials, just test-data
+		secretData = "U2FsdGVkX18cvbYVRsD5cxMKKAHtMRmteu88tPwRtOk="
+		//#nosec:G101 // Hardcoded credentials, just test-data
+		pass = "YQHdft6hDnp575olczeq"
+		s    Secret
+	)
+
+	err := s.read([]byte(secretData), pass)
+	require.NoError(t, err)
+
+	assert.Equal(t, Secret{
+		Secret: "I'm a secret!",
+	}, s)
+}
+
+func TestSerializeOTSMeta(t *testing.T) {
+	// NOTE(kahlers): We're using an empty passphrase here to achieve
+	// testability of the output. The data is not encrypted in this
+	// case.
+	data, err := Secret{
+		Secret: "I'm a secret!",
+		Attachments: []SecretAttachment{{
+			Name:    "secret.txt",
+			Type:    "text/plain",
+			Content: []byte("I'm a very secret file.\n"),
+		}},
+	}.serialize("")
+	require.NoError(t, err)
+
+	assert.Equal(t, []byte(`OTSMeta{"secret":"I'm a secret!","attachments":[{"name":"secret.txt","type":"text/plain","data":"SSdtIGEgdmVyeSBzZWNyZXQgZmlsZS4K"}]}`), data)
+}
+
+func TestSerializeSimpleSecret(t *testing.T) {
+	// NOTE(kahlers): We're using an empty passphrase here to achieve
+	// testability of the output. The data is not encrypted in this
+	// case.
+	data, err := Secret{Secret: "I'm a secret!"}.serialize("")
+	require.NoError(t, err)
+
+	assert.Equal(t, []byte("I'm a secret!"), data)
+}