Added test for crypt (#1)

* Added test for crypt

* Added test for crypt

* Added test for crypt

* Added test for crypt

* Added test for crypt

crypt/pem.go

@@ -0,0 +1,47 @@
+package crypt
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"fmt"
+)
+
+func GenerateKeyPair(bitSize int) ([]byte, []byte, error) {
+	if bitSize == 0 {
+		bitSize = 4096
+	}
+
+	if bitSize < 2048 {
+		return nil, nil, fmt.Errorf("key to weak. size must be greater than 2048")
+	}
+
+	if bitSize > 16384 {
+		return nil, nil, fmt.Errorf("key to large. size must be less than 16384")
+	}
+
+	key, err := rsa.GenerateKey(rand.Reader, bitSize)
+
+	if err != nil {
+		return nil, nil, err
+	}
+
+	keyPEM := pem.EncodeToMemory(
+		&pem.Block{
+			Type:  "RSA PRIVATE KEY",
+			Bytes: x509.MarshalPKCS1PrivateKey(key),
+		},
+	)
+
+	pub := key.Public()
+
+	pubPEM := pem.EncodeToMemory(
+		&pem.Block{
+			Type:  "RSA PUBLIC KEY",
+			Bytes: x509.MarshalPKCS1PublicKey(pub.(*rsa.PublicKey)),
+		},
+	)
+
+	return keyPEM, pubPEM, nil
+}