From 9469d0f61afbc786ddee0bc778950792f1774052 Mon Sep 17 00:00:00 2001
From: Aneurin Barker Snook <a@aneur.in>
Date: Tue, 10 Oct 2023 21:56:47 +0100
Subject: [PATCH] add simple hash functions, tests

---
 go.mod       |  3 +++
 hash.go      | 27 +++++++++++++++++++++++++++
 hash_test.go | 45 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+)
 create mode 100644 go.mod
 create mode 100644 hash.go
 create mode 100644 hash_test.go

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..f316f36
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/recipeer/go/hash
+
+go 1.21.2
diff --git a/hash.go b/hash.go
new file mode 100644
index 0000000..32f58fa
--- /dev/null
+++ b/hash.go
@@ -0,0 +1,27 @@
+package hash
+
+import (
+	"crypto/sha256"
+	"crypto/sha512"
+	"encoding/hex"
+)
+
+// SHA256 creates a hex-encoded SHA256 checksum for a string input.
+func SHA256(value string) string {
+	b := sha256.Sum256([]byte(value))
+	hash := []byte{}
+	for _, byte := range b {
+		hash = append(hash, byte)
+	}
+	return hex.EncodeToString(hash)
+}
+
+// SHA512 creates a hex-encoded SHA512 checksum for a string input.
+func SHA512(value string) string {
+	b := sha512.Sum512([]byte(value))
+	hash := []byte{}
+	for _, byte := range b {
+		hash = append(hash, byte)
+	}
+	return hex.EncodeToString(hash)
+}
diff --git a/hash_test.go b/hash_test.go
new file mode 100644
index 0000000..1671294
--- /dev/null
+++ b/hash_test.go
@@ -0,0 +1,45 @@
+package hash
+
+import "testing"
+
+func TestSHA256(t *testing.T) {
+	type TestCase struct {
+		Input  string
+		Output string
+	}
+
+	testCases := []TestCase{
+		{Input: "Gnocchi", Output: "5590208af75dc079e5e500fa39c982449ecbb02010f093a4de8b3377250c6f99"},
+		{Input: "Spaghetti", Output: "dd81cff28075d9126e35ce2ba895a3ce95a9ecdc1ac899418ace10e7a697127d"},
+	}
+
+	for i, tc := range testCases {
+		t.Logf("(%d) Testing %q", i, tc.Input)
+
+		out := SHA256(tc.Input)
+		if out != tc.Output {
+			t.Errorf("Expected %q, got %q", tc.Output, out)
+		}
+	}
+}
+
+func TestSHA512(t *testing.T) {
+	type TestCase struct {
+		Input  string
+		Output string
+	}
+
+	testCases := []TestCase{
+		{Input: "Gnocchi", Output: "43d0c2d7ee218cc30221c83e57c4ea3e6a68ce73225aff9b77c148e86f97c0b5d98a018a503115c4a81b9364cf132f5fc42878ece0412346aa60f2ea01f54756"},
+		{Input: "Spaghetti", Output: "259f2043005a92915be7bd288050cffdc4f55201c823b5837e22b053ef982e364bf3625ee41c676b91047a450b33e66660ec6346690b234c2a0c47c832043ef2"},
+	}
+
+	for i, tc := range testCases {
+		t.Logf("(%d) Testing %q", i, tc.Input)
+
+		out := SHA512(tc.Input)
+		if out != tc.Output {
+			t.Errorf("Expected %q, got %q", tc.Output, out)
+		}
+	}
+}