added some files

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
+}