diff --git a/encrypter/aes_ofb_encrypter.go b/encrypter/aes_ofb_encrypter.go
new file mode 100644
index 0000000..0c2a1f4
--- /dev/null
+++ b/encrypter/aes_ofb_encrypter.go
@@ -0,0 +1,67 @@
+package encrypter
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"io"
+)
+
+type AESOFBEncrypter struct {
+	randomReader io.Reader
+	iv           []byte
+	key          []byte
+}
+
+func NewAESOFBEncrypter() *AESOFBEncrypter {
+	ret := new(AESOFBEncrypter)
+	ret.randomReader = rand.Reader
+	return ret
+}
+
+func (this *AESOFBEncrypter) createSymetricKey(size int) ([]byte, error) {
+	key := make([]byte, size)
+	_, err := io.ReadFull(this.randomReader, key)
+	return key, err
+}
+
+func (this *AESOFBEncrypter) 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 *AESOFBEncrypter) createIV(block cipher.Block) (iv []byte, err error) {
+	return this.createSymetricKey(block.BlockSize())
+}
+
+func (this *AESOFBEncrypter) 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 *AESOFBEncrypter) createFileHandlerAndCypherBlock() (stream cipher.Stream, err error) {
+	cypherBlock, err := this.getCypherBlock()
+	if err != nil {
+		return nil, err
+	}
+	return this.createStreamMode(cypherBlock)
+}
+
+func (this *AESOFBEncrypter) EncryptReaderToWriter(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
+}
diff --git a/encrypter/aes_ofb_encrypter_test.go b/encrypter/aes_ofb_encrypter_test.go
new file mode 100644
index 0000000..d58e76f
--- /dev/null
+++ b/encrypter/aes_ofb_encrypter_test.go
@@ -0,0 +1,155 @@
+package encrypter
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	. "github.com/didiercrunch/ecrypto/helper"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func NewMockAESOFBEncrypter() *AESOFBEncrypter {
+	ret := new(AESOFBEncrypter)
+	ret.randomReader = NewMockRandomReader()
+	return ret
+}
+
+func TestCreateSymetricKey(t *testing.T) {
+	c := NewMockAESOFBEncrypter()
+	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, NewMockRandomReader().GetRandomBytes(512)) {
+		t.Fail()
+	}
+}
+
+func TestGetCypherBlock(t *testing.T) {
+	c := NewMockAESOFBEncrypter()
+	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 := Range(16)
+	dst := make([]byte, 16)
+	expected := []byte{30, 248, 157, 9, 161, 60, 109, 82, 221, 152, 171, 167, 137,
+		239, 177, 191}
+	expectedKey := []byte{73, 233, 188, 33, 31, 118, 98, 81, 66, 120, 254, 85, 138, 36,
+		118, 80, 38, 83, 169, 57, 27, 61, 103, 122, 37, 164, 185, 40, 112, 66, 1, 50}
+
+	block.Encrypt(dst, src)
+	if !reflect.DeepEqual(dst, expected) {
+		t.Error("bad aes encryption", dst)
+	}
+	if !reflect.DeepEqual(c.key, expectedKey) {
+		t.Error("bad key", c.key)
+	}
+}
+
+func TestNewEncrypter(t *testing.T) {
+	c := NewAESOFBEncrypter()
+	if c.randomReader != rand.Reader {
+		t.Fail()
+	}
+}
+
+func TestCreateIV(t *testing.T) {
+	m := NewMockAESOFBEncrypter()
+	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 := NewMockRandomReader().GetRandomBytes(16)
+	if !reflect.DeepEqual(iv, expt) {
+		t.Error("bad iv", iv)
+	}
+}
+
+func TestCreateStreamMode(t *testing.T) {
+	m := NewMockAESOFBEncrypter()
+	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 := NewMockRandomReader().GetRandomBytes(16)
+	if !reflect.DeepEqual(m.iv, exptIv) {
+		t.Error("bad iv", m.iv, " is not ", exptIv)
+	}
+}
+
+func TestCreateFileHandlerAndCypherBlock(t *testing.T) {
+	m := NewMockAESOFBEncrypter()
+	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, NewMockRandomReader().GetRandomBytes(32)) {
+		t.Error("bad key", m.key)
+	}
+	if !reflect.DeepEqual(m.iv, NewMockRandomReader().GetRandomBytes(32 + 16)[32:32+16]) {
+		t.Error("bad iv", m.iv)
+	}
+}
+
+func TestSimpleEncryptReaderToWriter(t *testing.T) {
+	reader := strings.NewReader("some plain text")
+	writer := NewMockIoWriter()
+	m := NewMockAESOFBEncrypter()
+	if err := m.EncryptReaderToWriter(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 := NewMockAESOFBEncrypter()
+	if err := m.EncryptReaderToWriter(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")
+	}
+}
diff --git a/encrypter/rsa_encryptor.go b/encrypter/rsa_encryptor.go
new file mode 100644
index 0000000..6a4b6a7
--- /dev/null
+++ b/encrypter/rsa_encryptor.go
@@ -0,0 +1,30 @@
+package encrypter
+
+import (
+	"crypto"
+	"crypto/rsa"
+	"crypto/sha512"
+	"io"
+)
+
+var _ = sha512.New
+
+type RsaSha512 struct {
+	PrivateKey *rsa.PrivateKey
+}
+
+func (this *RsaSha512) hashIOReader(input io.Reader) ([]byte, error) {
+	hashFunction := crypto.SHA512.New()
+	if _, err := io.Copy(hashFunction, input); err != nil {
+		return nil, err
+	}
+	return hashFunction.Sum(nil), nil
+}
+
+func (this *RsaSha512) SignStream(input io.Reader, rand io.Reader) ([]byte, error) {
+	hashed, err := this.hashIOReader(input)
+	if err != nil {
+		return nil, err
+	}
+	return rsa.SignPSS(rand, this.PrivateKey, crypto.SHA512, hashed, nil)
+}
diff --git a/encrypter/rsa_encryptor_test.go b/encrypter/rsa_encryptor_test.go
new file mode 100644
index 0000000..876d4b3
--- /dev/null
+++ b/encrypter/rsa_encryptor_test.go
@@ -0,0 +1,46 @@
+package encrypter
+
+import (
+	"bytes"
+	"crypto"
+	"crypto/rsa"
+	"crypto/sha512"
+	"fmt"
+	"github.com/didiercrunch/ecrypto/helper"
+	"testing"
+)
+
+func TestHashIOReader(t *testing.T) {
+	rs := new(RsaSha512)
+	expt := "fabbbe22180f1f137cfdc9556d2570e775d1ae02a597ded43a72a40f9b485d500043b7b" +
+		"e128fb9fcd982b83159a0d99aa855a9e7cc4240c00dc01a9bdf8218d7"
+	input := bytes.NewBufferString("C is as portable as Stonehedge!!")
+	if hashValue, err := rs.hashIOReader(input); err != nil {
+		t.Error(err)
+	} else if fmt.Sprintf("%x", hashValue) != expt {
+		t.Errorf("Hash is not the same \n expected : %s\n"+
+			"results  : %x  ", expt, hashValue)
+	}
+}
+
+func TestSignStream(t *testing.T) {
+	toSlice := func(data [sha512.Size]byte) []byte {
+		ret := make([]byte, sha512.Size)
+		for i, datum := range data {
+			ret[i] = datum
+		}
+		return ret
+	}
+	privateKey := helper.GetRSAPrivateKey(1024)
+	rs := &RsaSha512{privateKey}
+	input := bytes.NewBufferString("something to sign")
+	signature, err := rs.SignStream(input, helper.NewMockRandomReader())
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	hashed := toSlice(sha512.Sum512([]byte("something to sign")))
+	if err := rsa.VerifyPSS(&privateKey.PublicKey, crypto.SHA512, hashed, signature, nil); err != nil {
+		t.Error(err)
+	}
+}
diff --git a/helper/test_helper.go b/helper/test_helper.go
new file mode 100644
index 0000000..f0a3bae
--- /dev/null
+++ b/helper/test_helper.go
@@ -0,0 +1,94 @@
+package helper
+
+import (
+	"crypto/rsa"
+	"encoding/binary"
+	"math/big"
+	"math/rand"
+)
+
+func B(x int64) *big.Int {
+	return big.NewInt(x)
+}
+
+type MockRandomReader struct {
+	random *rand.Rand
+}
+
+func NewMockRandomReader() *MockRandomReader {
+	return &MockRandomReader{rand.New(rand.NewSource(99))}
+}
+
+func (this *MockRandomReader) getNextFourRandomBytes() []byte {
+	ret := make([]byte, 4)
+	binary.LittleEndian.PutUint32(ret, uint32(this.random.Int31()))
+	return ret
+}
+
+func (this *MockRandomReader) Read(p []byte) (n int, err error) {
+	for i := 0; i < len(p); i += 4 {
+		copy(p[i:], this.getNextFourRandomBytes())
+	}
+	return len(p), nil
+}
+
+func (this *MockRandomReader) GetRandomBytes(size int) []byte {
+	ret := make([]byte, size)
+	this.Read(ret)
+	return ret
+
+}
+
+type MockIoWriter struct {
+	state []byte
+}
+
+func NewMockIoWriter() *MockIoWriter {
+	return &MockIoWriter{make([]byte, 0, 1024)}
+}
+
+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 (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 GetRSAPublicKey(size int) *rsa.PublicKey {
+	return &GetRSAPrivateKey(size).PublicKey
+}
+
+func GetRSAPrivateKey(size int) *rsa.PrivateKey {
+	key, err := rsa.GenerateKey(NewMockRandomReader(), size)
+	if err != nil {
+		panic(err)
+	}
+	return key
+
+}
diff --git a/helper/test_helper_test.go b/helper/test_helper_test.go
new file mode 100644
index 0000000..8e378ea
--- /dev/null
+++ b/helper/test_helper_test.go
@@ -0,0 +1,100 @@
+package helper
+
+import (
+	"fmt"
+	"math/big"
+	"math/rand"
+	"reflect"
+	"testing"
+)
+
+func TestRange(t *testing.T) {
+	if !reflect.DeepEqual(Range(3), []byte{0, 1, 2}) {
+		t.Fail()
+	}
+}
+
+func TestFromRange(t *testing.T) {
+	if !reflect.DeepEqual(FromRange(3, 5), []byte{3, 4}) {
+		t.Fail()
+	}
+}
+
+func TestB(t *testing.T) {
+	if !reflect.DeepEqual(B(3), big.NewInt(3)) {
+		t.Fail()
+	}
+}
+
+func TestMockIoWriter(t *testing.T) {
+	w := NewMockIoWriter()
+	fmt.Fprint(w, "something to write")
+	if !reflect.DeepEqual(w.Bytes(), []byte("something to write")) {
+		t.Fail()
+	} else if "something to write" != w.String() {
+		t.Fail()
+	} else if w.Length() != len("something to write") {
+		t.Fail()
+	}
+}
+
+func TestGetRSAPublicKeyAndGetRSAPrivateKey(t *testing.T) {
+	privateKey := GetRSAPrivateKey(50)
+	if err := privateKey.Validate(); err != nil {
+		t.Error(err)
+		return
+	}
+	publicKey := GetRSAPublicKey(50)
+	if publicKey.E != privateKey.E || publicKey.N.Cmp(privateKey.N) != 0 {
+		t.Error("private and public keys do not match", publicKey.N, privateKey.N)
+	}
+
+	if publicKey.N.BitLen() != 50 {
+		t.Error("modulo has bad bit length")
+	}
+}
+
+func TestGetNextFourRandomBytes(t *testing.T) {
+	m := &MockRandomReader{rand.New(rand.NewSource(22))}
+	rb := m.getNextFourRandomBytes()
+	var expt []byte = []byte{233, 237, 107, 32}
+	if len(rb) != 4 {
+		t.Error("bad random length")
+		return
+	} else if !reflect.DeepEqual(expt, rb) {
+		t.Error("unexpect randome data")
+	}
+
+	rb = m.getNextFourRandomBytes()
+	expt = []byte{27, 131, 191, 20}
+	if len(rb) != 4 {
+		t.Error("bad random length")
+		return
+	} else if !reflect.DeepEqual(expt, rb) {
+		t.Error("unexpect randome data")
+	}
+}
+
+func TestMockRandomReader(t *testing.T) {
+	m := NewMockRandomReader()
+	dump := make([]byte, 4*10+3)
+	if l, err := m.Read(dump); l != len(dump) || err != nil {
+		t.Error("that is very bad :(")
+		return
+	}
+	var expt []byte = []byte{73, 233, 188, 33, 31, 118, 98, 81, 66, 120, 254, 85, 138,
+		36, 118, 80, 38, 83, 169, 57, 27, 61, 103, 122, 37, 164, 185, 40, 112, 66, 1,
+		50, 185, 128, 156, 20, 8, 164, 37, 13, 182, 50, 175}
+	if !reflect.DeepEqual(dump, expt) {
+		t.Error("unexpected returned data\n", dump)
+	}
+}
+
+func TestGetRandomBytes(t *testing.T) {
+	rdBytes := NewMockRandomReader().GetRandomBytes(10)
+	expt := make([]byte, 10)
+	NewMockRandomReader().Read(expt)
+	if !reflect.DeepEqual(expt, rdBytes) {
+		t.Fail()
+	}
+}
diff --git a/something.go b/something.go
new file mode 100644
index 0000000..95a12d9
--- /dev/null
+++ b/something.go
@@ -0,0 +1,27 @@
+package main
+
+import (
+	"io"
+)
+
+type Params struct {
+}
+
+type Envelop struct {
+	err    error
+	params *Params
+}
+
+func ZipIoReader(reader io.Reader) {
+
+}
+
+func createEnvelop(reader io.Reader, writer io.WriteCloser, params *Params) error {
+	env := &Envelop{nil, params}
+	env.ZipDataForPayload()
+	env.CreatePayloadMetadata()
+	env.EncryptPayload()
+	env.CreateEnvelopMetadata()
+	env.EncryptPayloadKeyAndAddItToEncelop()
+	return env.getError()
+}