Add core file

.gitignore

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+.idea
+*.iml
+.DS_STORE
+.lein-repl-history
+.nrepl-port
+pom.xml
+/target

README.md

@@ -1,2 +1,2 @@
 # adyen-signature
-Easy way to sign adyen request
+A clojure library designed to sign adyen requests

project.clj

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+(defproject adyen-signature "0.1.0"
+  :description "A clojure library designed to sign adyen requests"
+  :url "https://github.com/rackdon/adyen-signature"
+  :license {:name "MIT License"}
+
+  :dependencies [[org.clojure/clojure "1.8.0"]
+                 [org.clojure/data.codec "0.1.0"]
+                 [com.google.guava/guava "23.0"]])

src/adyen_signature/core.clj

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+(ns adyen-signature.core
+  (:require [clojure.data.codec.base64 :as b64]
+            [clojure.string :as string])
+  (:import [javax.crypto.spec SecretKeySpec]
+           [javax.crypto Mac]
+           [com.google.common.io BaseEncoding]))
+
+(defn to-camel-case [s]
+  (as-> (name s) $
+        (string/lower-case $)
+        (string/split $ #"-")
+        (map-indexed (fn [idx itm] (if (= idx 0) itm (string/capitalize itm))) $)
+        (string/join $)))
+
+(defn replace-values [s]
+  (if (nil? s)
+    ""
+    (string/replace s #"\\|:" {"\\" "\\\\" ":" "\\:"})))
+
+(defn to-byte-array [s]
+  "Convert an string to byte array"
+  (into-array Byte/TYPE (.getBytes s "UTF-8")))
+
+(defn decode-hex [s]
+  "Convert hex string into Byte Array"
+  (.decode (BaseEncoding/base16) s))
+
+(defn encode-b64-string [ba]
+  "Convert a byte array to a base64 String"
+  (String. (b64/encode ba) "UTF-8"))
+
+(defn sign [secret data]
+  (let [sha256-mac (Mac/getInstance "HmacSHA256")
+        signing-key (SecretKeySpec. (decode-hex secret) "HmacSHA256")
+        byte-data (->> (map (fn [[k v]] [(to-camel-case k) (replace-values v)]) (dissoc data :merchant-sig))
+                       sort
+                       (into {})
+                       ((fn [coll] (concat (keys coll) (vals coll))))
+                       (string/join ":")
+                       to-byte-array)]
+
+    (.init sha256-mac signing-key)
+    (encode-b64-string (.doFinal sha256-mac byte-data))))