started to implements the encryption process

.gitignore

@@ -1,3 +1,6 @@
+
+
+*cover.out
 /ecrypto
 # Compiled Object files, Static and Dynamic libs (Shared Objects)
 *.o

doc/fileformat.md

@@ -0,0 +1,25 @@
+
+### public key
+Note that any private key are a public key.
+
+~~~
+
+~~~
+
+### private key
+
+
+
+
+### cypher format
+
+We use the `.cyp` file extension for the encrypted file.  A .cyp is nothing
+else than a zip file containing the following shit.
+
+1.  a `data.encrypted` containing the encrypted data
+2.  a `meta_data.yml` file containing the meta data of the encrypted file
+    *  symetric encryption algorithm
+    *  mode
+    *  encrypted symetric key
+    *  hash of the encrypted data (always use full for validation)
+3.  a 'signature' file with the signature of the `meta_data.yml` file

encrypter/encrypter.go

@@ -1,16 +1,77 @@
 package encrypter
 
 import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
 	"github.com/didiercrunch/ecrypto/keys"
+	"io"
 )
 
-type Encrypter struct {
+type FileEncrypter struct {
 	PublicKey    keys.PublicKey
 	PrivateKey   keys.PrivateKey
 	InputPath    string
 	OutputPath   string
+	randomReader io.Reader
+
+	iv  []byte
+	key []byte
 }
 
-func (this *Encrypter) Encrypt() error {
-	// encrypt file
+func NewEncrypter() *FileEncrypter {
+	ret := new(FileEncrypter)
+	ret.randomReader = rand.Reader
+	return ret
+}
+
+func (this *FileEncrypter) createSymetricKey(size int) ([]byte, error) {
+	key := make([]byte, size)
+	_, err := io.ReadFull(this.randomReader, key)
+	return key, err
+}
+
+func (this *FileEncrypter) getCypherBlock() (cipher.Block, error) {
+	var err error
+	this.key, err = this.createSymetricKey(32)
+	if err != nil {
+		return nil, err
+	}
+	return aes.NewCipher(this.key)
+}
+
+func (this *FileEncrypter) createIV(block cipher.Block) (iv []byte, err error) {
+	return this.createSymetricKey(block.BlockSize())
+}
+
+func (this *FileEncrypter) createStreamMode(block cipher.Block) (stream cipher.Stream, err error) {
+	this.iv, err = this.createIV(block)
+	if err != nil {
+		return nil, err
+	}
+	return cipher.NewOFB(block, this.iv), err
+}
+
+func (this *FileEncrypter) createFileHandlerAndCypherBlock() (stream cipher.Stream, err error) {
+	cypherBlock, err := this.getCypherBlock()
+	if err != nil {
+		return nil, err
+	}
+	return this.createStreamMode(cypherBlock)
+}
+
+func (this *FileEncrypter) encrypeReaderToWriter(clearInput io.Reader, encryptedOutput io.Writer) error {
+	stream, err := this.createFileHandlerAndCypherBlock()
+	if err != nil {
+		return err
+	}
+	writer := &cipher.StreamWriter{S: stream, W: encryptedOutput}
+	if _, err := io.Copy(writer, clearInput); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (this *FileEncrypter) Encrypt() error {
+	return nil
 }

encrypter/encrypter_test.go

@@ -0,0 +1,204 @@
+package encrypter
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"fmt"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+var _ = fmt.Print
+
+type mockIoWriter struct {
+	state []byte
+}
+
+func (this *mockIoWriter) Write(p []byte) (n int, err error) {
+	this.state = append(this.state, p...)
+	return len(p), nil
+}
+
+func (this *mockIoWriter) String() string {
+	return string(this.state)
+}
+
+func newMockIoWriter() *mockIoWriter {
+	return &mockIoWriter{make([]byte, 0, 1024)}
+}
+
+func (this *mockIoWriter) Length() int {
+	return len(this.state)
+}
+
+func (this *mockIoWriter) Bytes() []byte {
+	return this.state
+}
+
+func range_(length int) []byte {
+	ret := make([]byte, length)
+	for i, _ := range ret {
+		ret[i] = byte(i)
+	}
+	return ret
+}
+func fromRange(from, to int) []byte {
+	ret := make([]byte, to-from)
+	for i, _ := range ret {
+		ret[i] = byte(i + from)
+	}
+	return ret
+}
+
+func createMockRandomData(length int) []byte {
+	ret := make([]byte, length)
+	for i, _ := range ret {
+		ret[i] = byte(i)
+	}
+	return ret
+}
+
+func NewMockEncrypter() *FileEncrypter {
+	ret := new(FileEncrypter)
+	mockRandomData := createMockRandomData(1024)
+	ret.randomReader = bytes.NewReader(mockRandomData)
+	return ret
+}
+
+func TestCreateSymetricKey(t *testing.T) {
+	c := NewMockEncrypter()
+	key, e := c.createSymetricKey(512)
+	if e != nil {
+		t.Error(e)
+	} else if len(key) != 512 {
+		t.Error("bad key lenght")
+	} else if !reflect.DeepEqual(key, createMockRandomData(512)) {
+		t.Fail()
+	}
+}
+
+func TestGetCypherBlock(t *testing.T) {
+	c := NewMockEncrypter()
+	if c.key != nil {
+		t.Error("expected nil key at this point")
+	}
+	block, err := c.getCypherBlock()
+	if err != nil {
+		t.Error(err)
+	}
+	if block.BlockSize() != 16 {
+		t.Fail()
+	}
+	src := createMockRandomData(16)
+	dst := make([]byte, 16)
+	expected := []byte{90, 110, 4, 87, 8, 251, 113, 150, 240, 46, 85, 61, 2, 195, 166, 146}
+
+	block.Encrypt(dst, src)
+	if !reflect.DeepEqual(dst, expected) {
+		t.Error("bad aes encryption")
+	}
+	if !reflect.DeepEqual(c.key, range_(32)) {
+		t.Error("bad key", c.key)
+	}
+}
+
+func TestNewEncrypter(t *testing.T) {
+	c := NewEncrypter()
+	if c.randomReader != rand.Reader {
+		t.Fail()
+	}
+}
+
+func TestCreateIV(t *testing.T) {
+	m := NewMockEncrypter()
+	b, err := aes.NewCipher([]byte("example key 1234"))
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	iv, err := m.createIV(b)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	expt := range_(16)
+	if !reflect.DeepEqual(iv, expt) {
+		t.Error("bad iv", iv)
+	}
+}
+
+func TestCreateStreamMode(t *testing.T) {
+	m := NewMockEncrypter()
+	if m.iv != nil {
+		t.Error("expected nil iv at first")
+	}
+	b, err := aes.NewCipher([]byte("example key 1234"))
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	_, err = m.createStreamMode(b)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	exptIv := []byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
+	if !reflect.DeepEqual(m.iv, exptIv) {
+		t.Error("bad iv", m.iv)
+	}
+}
+
+func TestCreateFileHandlerAndCypherBlock(t *testing.T) {
+	m := NewMockEncrypter()
+	if m.iv != nil {
+		t.Error("expected nil iv at first")
+	}
+
+	_, err := m.createFileHandlerAndCypherBlock()
+	if err != nil {
+		t.Error(err)
+	}
+	if !reflect.DeepEqual(m.key, range_(32)) {
+		t.Error("bad key", m.key)
+	}
+	if !reflect.DeepEqual(m.iv, fromRange(32, 32+16)) {
+		t.Error("bad iv", m.iv)
+	}
+}
+
+func TestSimpleEncrypeReaderToWriter(t *testing.T) {
+	reader := strings.NewReader("some plain text")
+	writer := newMockIoWriter()
+	m := NewMockEncrypter()
+	if err := m.encrypeReaderToWriter(reader, writer); err != nil {
+		t.Error(err)
+	}
+}
+
+func decryptEncryptedTextWithAESAlgorithmAndOFBMode(key, iv, encryptedText []byte) (string, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return "", err
+	}
+	stream := cipher.NewOFB(block, iv)
+	ret := make([]byte, len(encryptedText))
+	stream.XORKeyStream(ret, encryptedText)
+	return string(ret), nil
+}
+
+func TestEncryptDecrypt(t *testing.T) {
+	reader := strings.NewReader("some plain text")
+	writer := newMockIoWriter()
+	m := NewMockEncrypter()
+	if err := m.encrypeReaderToWriter(reader, writer); err != nil {
+		t.Error(err)
+	}
+	if plaintext2, err := decryptEncryptedTextWithAESAlgorithmAndOFBMode(m.key, m.iv, writer.Bytes()); err != nil {
+		t.Error(err)
+	} else if string(plaintext2) != "some plain text" {
+		t.Error("bad encryption/decryption process")
+	}
+}

keygenerator/key_generator.go

@@ -26,7 +26,6 @@ func (this *KeyGenerator) ensureDirectoryExists(dir string) error {
 		return errors.New(dir + " is not a directory")
 	}
 	return nil
-
 }
 
 func (this *KeyGenerator) saveKeyAsJSON(key interface{}, filepath string) error {