listening to "garoche ta sacoche"

asymetric/rsa.go

@@ -48,9 +48,6 @@ func (this *RsaOaepPss) Decrypt(ciphertext []byte) ([]byte, error) {
 
 func (this *RsaOaepPss) Sign(hashedData []byte) ([]byte, error) {
 	ret, err := rsa.SignPSS(this.Random, this.PrivateKey, this.Hash, hashedData, nil)
-	if err != nil {
-		fmt.Println(">>> ", len(hashedData))
-	}
 	return ret, err
 }
 

contract/best_contract.go

@@ -0,0 +1,79 @@
+package contract
+
+import (
+	"errors"
+	"strings"
+)
+
+type AcceptedContract struct {
+	Hash                  string
+	BlockCipher           string
+	BlockCipherMode       string
+	AsymetricCryptography string
+}
+
+func listContains(lst []string, elm string) bool {
+	for _, elm_ := range lst {
+		if elm == elm_ {
+			return true
+		}
+	}
+	return false
+}
+
+func joinAsError(msg []string) error {
+	if len(msg) > 0 {
+		return errors.New(strings.Join(msg, "\n"))
+	}
+	return nil
+}
+
+func getFirstItemInList1ThatIsAlsoInList2(lst1, lst2 []string) (string, error) {
+	for _, elm := range lst1 {
+		if listContains(lst2, elm) {
+			return elm, nil
+		}
+	}
+	return "", errors.New("no items in list1 is in list2")
+}
+
+func getBestBlockCipher(prvCtr *PrivateContract, pubCtr *PublicContract) (string, error) {
+	if b, err := getFirstItemInList1ThatIsAlsoInList2(pubCtr.AcceptedBlockCyphers, prvCtr.AcceptedBlockCyphers); err != nil {
+		return "", errors.New("cannot find a block cypher that satisfy both contracts")
+	} else {
+		return b, nil
+	}
+}
+
+func getBestBlockCipherMode(prvCtr *PrivateContract, pubCtr *PublicContract) (string, error) {
+	if m, err := getFirstItemInList1ThatIsAlsoInList2(pubCtr.AcceptedBlockCypherModes, prvCtr.AcceptedBlockCypherModes); err != nil {
+		return "", errors.New("cannot find a block cypher mode that satisfy both contracts")
+	} else {
+		return m, nil
+	}
+}
+
+func getBestHash(prvCtr *PrivateContract, pubCtr *PublicContract) (string, error) {
+	if h, err := getFirstItemInList1ThatIsAlsoInList2(pubCtr.AcceptedHashes, prvCtr.AcceptedHashes); err != nil {
+		return "", errors.New("cannot find a hash that satisfy both contracts")
+	} else {
+		return h, nil
+	}
+}
+
+func GetAcceptedContract(prvCtr *PrivateContract, pubCtr *PublicContract) (*AcceptedContract, error) {
+	ret := new(AcceptedContract)
+	errs := make([]string, 0, 4)
+	var err error
+	if ret.Hash, err = getBestHash(prvCtr, pubCtr); err != nil {
+		errs = append(errs, err.Error())
+	}
+	if ret.BlockCipher, err = getBestBlockCipher(prvCtr, pubCtr); err != nil {
+		errs = append(errs, err.Error())
+	}
+	if ret.BlockCipherMode, err = getBestBlockCipherMode(prvCtr, pubCtr); err != nil {
+		errs = append(errs, err.Error())
+	}
+
+	return ret, joinAsError(errs)
+}

contract/best_contract_test.go

@@ -0,0 +1,63 @@
+package contract
+
+import (
+	"testing"
+)
+
+func TestGetBestHash(t *testing.T) {
+	prvCtr := new(PrivateContract)
+	pubCtr := new(PublicContract)
+
+	pubCtr.AcceptedHashes = []string{"SHA384", "SHA256", "MD5"}
+	prvCtr.AcceptedHashes = []string{"SHA384", "SHA256"}
+	if h, err := getBestHash(prvCtr, pubCtr); err != nil {
+		t.Error(err)
+	} else if h != "SHA384" {
+		t.Error("bad choosen hash: ", h)
+	}
+	prvCtr.AcceptedHashes = []string{"SHA1", "MD4"}
+	if h, err := getBestHash(prvCtr, pubCtr); err == nil {
+		t.Error("should have an error here")
+	} else if h != "" {
+		t.Error("should not have choosen any hash function here")
+	}
+}
+
+func TestGetFirstItemInList1ThatIsAlsoInList2(t *testing.T) {
+	lst1 := []string{"a", "b", "c"}
+	lst2 := []string{"b", "c"}
+	if c, err := getFirstItemInList1ThatIsAlsoInList2(lst1, lst2); c != "b" || err != nil {
+		t.Fail()
+	}
+	lst2 = []string{"d", "e"}
+	if c, err := getFirstItemInList1ThatIsAlsoInList2(lst1, lst2); c != "" || err == nil {
+		t.Fail()
+	}
+}
+
+func TestGetAcceptedContract(t *testing.T) {
+	prvCtr := new(PrivateContract)
+	pubCtr := new(PublicContract)
+
+	pubCtr.AcceptedHashes = []string{"SHA384", "SHA256", "MD5"}
+	prvCtr.AcceptedHashes = []string{"SHA384", "SHA256"}
+
+	pubCtr.AcceptedBlockCyphers = []string{"aes", "des"}
+	prvCtr.AcceptedBlockCyphers = []string{"aes"}
+
+	pubCtr.AcceptedBlockCypherModes = []string{"ofb"}
+	prvCtr.AcceptedBlockCypherModes = []string{"ofb"}
+
+	ac, err := GetAcceptedContract(prvCtr, pubCtr)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	if ac.Hash != "SHA384" {
+		t.Error("bad hash")
+	}
+	if ac.BlockCipher != "aes" {
+		t.Error("bad block cipher")
+	}
+
+}

contract/public_contract.go

@@ -6,6 +6,7 @@ import (
 
 type PublicContract struct {
 	AcceptedHashes           []string             `yaml:"accepted_hashes" json:"accepted_hashes"`
-	AcceptedBlockCypher []string             `yaml:"accepted_block_cypher" json:"accepted_block_cypher"`
+	AcceptedBlockCyphers     []string             `yaml:"accepted_block_cypher" json:"accepted_block_cypher"`
+	AcceptedBlockCypherModes []string             `yaml:"accepted_block_cypher_mode" json:"accepted_block_cypher_mode"`
 	RSAPublicKey             []*keys.RSAPublicKey `yaml:"rsa_public_key, omitempty" json:"rsa_public_key,omitempty"`
 }

contract/public_contract_test.go

@@ -37,7 +37,7 @@ func expectJson(c *PublicContract, jsonData string) error {
 func TestSimpleJsonification(t *testing.T) {
 	c := &PublicContract{
 		AcceptedHashes:       []string{"sha246"},
-		AcceptedBlockCypher: []string{"aes"},
+		AcceptedBlockCyphers: []string{"aes"},
 		RSAPublicKey:         []*keys.RSAPublicKey{&keys.RSAPublicKey{helper.B(12), 3}},
 	}
 	if err := assertJSONMarshalling(c); err != nil {
@@ -48,7 +48,7 @@ func TestSimpleJsonification(t *testing.T) {
 func TestEmptyRSAPublicKey(t *testing.T) {
 	c := &PublicContract{
 		AcceptedHashes:       []string{"sha246"},
-		AcceptedBlockCypher: []string{"aes"},
+		AcceptedBlockCyphers: []string{"aes"},
 		RSAPublicKey:         []*keys.RSAPublicKey{&keys.RSAPublicKey{helper.B(12), 3}},
 	}
 	jsonData := `{

doc/fileformat.md

@@ -24,13 +24,16 @@ url: "the url where to fiofbnd an exact copy of the contract"
 root_url: "the url where to find the most up to date version of the contract"
 
 accepted_hashs:
-	- sha512
+	- sha512    #  first choice
+	- sha256    #  second choice
 
 accepted_block_cypher:
-	- aes
+	- aes	    #  first choice
+	- 3des      #  second choice
 
 accepted_modes:
-	- ofb
+	- ofb       #  first choice
+	- cbc       #  second choice
 
 signatures_required: yes
 

integration/enveloppayload_test.go

@@ -13,19 +13,6 @@ import (
 	"github.com/didiercrunch/filou/payload"
 )
 
-type mockEncryptor struct{}
-
-func (this *mockEncryptor) Encrypt(data []byte) ([]byte, error) {
-	// cesar encryption!
-	ret := make([]byte, len(data))
-	for i, d := range data {
-		ret[i] = d + 3 // modulo is implicit
-	}
-	return ret, nil
-}
-
-type mockSigner struct{}
-
 var random = helper.NewMockRandomReader()
 
 func generateRSAKeyPair() (*rsa.PrivateKey, *rsa.PublicKey) {
@@ -42,15 +29,6 @@ func getEncryterAndSigner() *asymetric.RsaOaepPss {
 	return &asymetric.RsaOaepPss{alicePrivateKey, bobPubKey, crypto.SHA512, random}
 }
 
-func (this *mockSigner) Sign(data []byte) ([]byte, error) {
-	// a slice with the sum of the data plus a "secret" value
-	var sum byte = 36
-	for _, d := range data {
-		sum += d
-	}
-	return []byte{sum}, nil
-}
-
 func TestPayloadCanBeUseInEnvelop(t *testing.T) {
 	encryterAndSigner := getEncryterAndSigner()
 	payload_ := payload.GetDefaultPayload(bytes.NewBufferString("some data to encrypt"))