first commit

Marko Tikvić
Showing 2 changed files with 71 additions and 0 deletions Show diff stats
README.md
main.go
@@ -0,0 +1 @@
+### Link to the original source: [Advanced encryption and decryption](https://astaxie.gitbooks.io/build-web-application-with-golang/content/en/09.6.html)
@@ -0,0 +1,70 @@
+package aes
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"errors"
+	"io"
+	mrand "math/rand"
+	"time"
+)
+
+const (
+	keySize      = 32
+	allowedRunes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+)
+
+// RandomKey returns a randomly generated 32 bytes long hex encoded key.
+func RandomKey() (key []byte) {
+	mrand.Seed(time.Now().UnixNano())
+
+	key = make([]byte, keySize)
+
+	for i := range key {
+		key[i] = allowedRunes[mrand.Intn(len(allowedRunes))]
+	}
+
+	return key
+}
+
+// Encrypt encrypts plaintext with key and returns resulting bytes.
+func Encrypt(plaintext []byte, key []byte) ([]byte, error) {
+	c, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(c)
+	if err != nil {
+		return nil, err
+	}
+
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+
+	return gcm.Seal(nonce, nonce, plaintext, nil), nil
+}
+
+// Decrypt decrypts ciphertext with key and returns resulting bytes.
+func Decrypt(ciphertext []byte, key []byte) ([]byte, error) {
+	c, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(c)
+	if err != nil {
+		return nil, err
+	}
+
+	nonceSize := gcm.NonceSize()
+	if len(ciphertext) < nonceSize {
+		return nil, errors.New("ciphertext too short")
+	}
+
+	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
+	return gcm.Open(nil, nonce, ciphertext, nil)
+}
...	...	@@ -0,0 +1 @@
	1	+### Link to the original source: [Advanced encryption and decryption](https://astaxie.gitbooks.io/build-web-application-with-golang/content/en/09.6.html)
...	...
...	...	@@ -0,0 +1,70 @@
	1	+package aes
	2	+
	3	+import (
	4	+ "crypto/aes"
	5	+ "crypto/cipher"
	6	+ "crypto/rand"
	7	+ "errors"
	8	+ "io"
	9	+ mrand "math/rand"
	10	+ "time"
	11	+)
	12	+
	13	+const (
	14	+ keySize = 32
	15	+ allowedRunes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	16	+)
	17	+
	18	+// RandomKey returns a randomly generated 32 bytes long hex encoded key.
	19	+func RandomKey() (key []byte) {
	20	+ mrand.Seed(time.Now().UnixNano())
	21	+
	22	+ key = make([]byte, keySize)
	23	+
	24	+ for i := range key {
	25	+ key[i] = allowedRunes[mrand.Intn(len(allowedRunes))]
	26	+ }
	27	+
	28	+ return key
	29	+}
	30	+
	31	+// Encrypt encrypts plaintext with key and returns resulting bytes.
	32	+func Encrypt(plaintext []byte, key []byte) ([]byte, error) {
	33	+ c, err := aes.NewCipher(key)
	34	+ if err != nil {
	35	+ return nil, err
	36	+ }
	37	+
	38	+ gcm, err := cipher.NewGCM(c)
	39	+ if err != nil {
	40	+ return nil, err
	41	+ }
	42	+
	43	+ nonce := make([]byte, gcm.NonceSize())
	44	+ if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
	45	+ return nil, err
	46	+ }
	47	+
	48	+ return gcm.Seal(nonce, nonce, plaintext, nil), nil
	49	+}
	50	+
	51	+// Decrypt decrypts ciphertext with key and returns resulting bytes.
	52	+func Decrypt(ciphertext []byte, key []byte) ([]byte, error) {
	53	+ c, err := aes.NewCipher(key)
	54	+ if err != nil {
	55	+ return nil, err
	56	+ }
	57	+
	58	+ gcm, err := cipher.NewGCM(c)
	59	+ if err != nil {
	60	+ return nil, err
	61	+ }
	62	+
	63	+ nonceSize := gcm.NonceSize()
	64	+ if len(ciphertext) < nonceSize {
	65	+ return nil, errors.New("ciphertext too short")
	66	+ }
	67	+
	68	+ nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
	69	+ return gcm.Open(nil, nonce, ciphertext, nil)
	70	+}
...	...