PasswordCrypto.cs

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// 
//  Copyright 2010-2015 Deveel
// 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
// 
//        http://www.apache.org/licenses/LICENSE-2.0
// 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

using System;
using System.Text;

namespace Deveel.Data.Security {
    public sealed class PasswordCrypto {
        public PasswordCrypto(string hashName, int keyLength) {
            KeyLength = keyLength;
            HashName = hashName;

            var hash = HashFunctions.GetFunction(hashName);
            if (hash == null)
                throw new ArgumentException(String.Format("Hash function {0} is not supported.", hashName));
            if (!(hash is IKeyedHashFunction))
                throw new ArgumentException(String.Format("Hash function {0} does not handle keys.", hashName));

            HashFunction = hash as IKeyedHashFunction;
        }

        public string HashName { get; private set; }

        public int KeyLength { get; private set; }

        private IKeyedHashFunction HashFunction { get; set; }

        public string Hash(string password, out string salt) {
            salt = HashFunction.GenerateSaltString();
            return HashFunction.MakePbkdf2String(password, salt, 32);
        }

        public bool Verify(string hashedPassword, string password, string salt) {
            return HashFunction.VerifyPbkdf2String(hashedPassword, password, salt);
        }

        public override string ToString() {
            return String.Format("{0}({1})", HashName, KeyLength);
        }

        public static PasswordCrypto Parse(string defString) {
            if (String.IsNullOrEmpty(defString))
                throw new ArgumentNullException("defString");

            var sIndex = defString.IndexOf('(');
            if (sIndex == -1)
                throw new FormatException();

            var eIndex = defString.IndexOf(')');
            if (eIndex == -1)
                throw new FormatException();

            var hashName = defString.Substring(0, sIndex);
            var sKeyLength = defString.Substring(sIndex + 1, eIndex - (sIndex + 1));

            hashName = hashName.Trim();

            if (String.IsNullOrEmpty(hashName))
                throw new FormatException();

            int keyLength;
            if (!Int32.TryParse(sKeyLength, out keyLength))
                throw new FormatException();

            return new PasswordCrypto(hashName, keyLength);
        }
    }
}