my computer is about to die!!!

payload/block.go

@@ -45,3 +45,11 @@ func (this Block) CreateBlock(rd io.Reader) (cipher.Block, []byte, error) {
 	block, err := aes.NewCipher(key)
 	return block, key, err
 }
+
+func GetBlockByBlockName(blockName string) (Block, error) {
+	ret := Hash(hashName)
+	if _, err := ret.New(); err != nil {
+		return "", errors.New("block encryption " + blockName + " is not supported")
+	}
+	return ret, nil
+}

payload/hash.go

@@ -12,6 +12,14 @@ type Hash string
 
 const SHA512 Hash = "sha512"
 
+func GetHashByHashName(hashName string) (Hash, error) {
+	ret := Hash(hashName)
+	if _, err := ret.New(); err != nil {
+		return "", errors.New("unsupported hash function " + hashName)
+	}
+	return ret, nil
+}
+
 func (this Hash) New() (hash.Hash, error) {
 	switch this {
 	case SHA512:

payload/hash_test.go

@@ -14,8 +14,6 @@ import (
 	"github.com/didiercrunch/filou/helper"
 )
 
-var __ = ioutil.Discard
-
 func TestUnsupportedHash(t *testing.T) {
 	unsupportedHashes := []Hash{"md5"}
 	for _, h := range unsupportedHashes {
@@ -77,3 +75,21 @@ func TestHashOnTheWay(t *testing.T) {
 		t.Error("bad hash\nexpected: ", expectedHash, "\nreceived:", outputHash)
 	}
 }
+
+func TestGetHashByHashNameForAcceptedHashFunctions(t *testing.T) {
+	acceptedHashFunctions := []string{"sha512"}
+	for _, h := range acceptedHashFunctions {
+		if _, err := GetHashByHashName(h); err != nil {
+			t.Error(err)
+		}
+	}
+}
+
+func TestGetHashByHashNameForNotAcceptedHashFunctions(t *testing.T) {
+	unaccepterHashFunctions := []string{"md5"}
+	for _, h := range unaccepterHashFunctions {
+		if _, err := GetHashByHashName(h); err == nil {
+			t.Error("should never accept hash function " + h)
+		}
+	}
+}

payload/payload.go

@@ -6,6 +6,8 @@ import (
 	"crypto/rand"
 	"encoding/json"
 	"io"
+
+	"github.com/didiercrunch/filou/contract"
 )
 
 type BlockModeStream func(block cipher.Block, iv []byte) cipher.Stream
@@ -32,6 +34,17 @@ func GetDefaultPayload(dataSource io.Reader) *Payload {
 	}
 }
 
+func GetPayload(dataSource io.Reader, acceptedContract *contract.AcceptedContract) (*Payload, error) {
+	ret := &Payload{DataSource: dataSource, Random: rand.Reader}
+	errs := make([]error, 0)
+	var err error
+	if ret.HashMethod, err = GetHashByHashName(acceptedContract.Hash); err != nil {
+		errs = append(errs, err)
+	}
+
+	return ret, nil
+}
+
 type payloadWriter struct {
 	Reader     io.Reader
 	Pipewriter io.WriteCloser

payload/payload_test.go

@@ -2,12 +2,14 @@ package payload
 
 import (
 	"bytes"
+	"crypto/rand"
 	"errors"
 	"fmt"
 	"io/ioutil"
 	"reflect"
 	"testing"
 
+	"github.com/didiercrunch/filou/contract"
 	"github.com/didiercrunch/filou/helper"
 )
 
@@ -166,3 +168,23 @@ func TestGetDefaultPayload(t *testing.T) {
 		errorC <- errors.New("hash has not been computed")
 	}
 }
+
+func TestGetPayload(t *testing.T) {
+	c := &contract.AcceptedContract{Hash: "sha512"}
+	p, err := GetPayload(nil, c)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	expectedPayload := &Payload{
+		DataSource: nil,
+		Random:     rand.Reader,
+		HashMethod: SHA512,
+		Block:      AES256,
+		BlockMode:  OFB,
+	}
+	if p.HashMethod != expectedPayload.HashMethod {
+		t.Error("bad hash method")
+	}
+
+}