Revert "Switch phone number hashing to use scrypt (ethereum#342)" (et…

…hereum#344)

This reverts commit b58f3c4.

abe/abe.go

@@ -22,56 +22,25 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"golang.org/x/crypto/scrypt"
 	"net/http"
 	"regexp"
 	"time"
 
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
 )
 
-var ScryptParams = struct {
-	salt  []byte
-	N     int
-	r     int
-	p     int
-	dkLen int
-}{
-	[]byte("nNWKc3l0a1fAj0r35BLGB8kn"),
-	512,
-	16,
-	1,
-	32,
-}
-
-func hashPhoneNumber(phoneNumber []byte) ([]byte, error) {
-	return scrypt.Key(
-		phoneNumber,
-		ScryptParams.salt,
-		ScryptParams.N,
-		ScryptParams.r,
-		ScryptParams.p,
-		ScryptParams.dkLen,
-	)
-}
-
 func decryptPhoneNumber(request types.AttestationRequest, account accounts.Account, wallet accounts.Wallet) (string, error) {
 	phoneNumber, err := wallet.Decrypt(account, request.EncryptedPhone, nil, nil)
 	if err != nil {
 		return "", err
 	}
 	// TODO(asa): Better validation of phone numbers
 	r, _ := regexp.Compile(`^\+[0-9]{8,15}$`)
-
-	hashedPhone, err := hashPhoneNumber(phoneNumber)
-	if err != nil {
-		return "Hashing phone number failed", err
-	}
-
-	if !bytes.Equal(hashedPhone, request.PhoneHash.Bytes()) {
+	if !bytes.Equal(crypto.Keccak256(phoneNumber), request.PhoneHash.Bytes()) {
 		return string(phoneNumber), errors.New("Phone hash doesn't match decrypted phone number")
 	} else if !r.MatchString(string(phoneNumber)) {
 		return string(phoneNumber), fmt.Errorf("Decrypted phone number invalid: %s", string(phoneNumber))