bitwarden-mobile/src/Core/Models/Domain/SymmetricCryptoKey.cs

using Bit.Core.Enums;

namespace Bit.Core.Models.Domain
{
    public class SymmetricCryptoKey
    {
        public SymmetricCryptoKey(byte[] key, EncryptionType? encType = null)
        {
            if (key == null)
            {
                throw new ArgumentKeyNullException(nameof(key));
            }

            if (encType == null)
            {
                if (key.Length == 32)
                {
                    encType = EncryptionType.AesCbc256_B64;
                }
                else if (key.Length == 64)
                {
                    encType = EncryptionType.AesCbc256_HmacSha256_B64;
                }
                else
                {
                    throw new InvalidKeyOperationException("Unable to determine encType.");
                }
            }

            Key = key;
            EncType = encType.Value;

            if (EncType == EncryptionType.AesCbc256_B64 && Key.Length == 32)
            {
                EncKey = Key;
                MacKey = null;
            }
            else if (EncType == EncryptionType.AesCbc128_HmacSha256_B64 && Key.Length == 32)
            {
                EncKey = new ArraySegment<byte>(Key, 0, 16).ToArray();
                MacKey = new ArraySegment<byte>(Key, 16, 16).ToArray();
            }
            else if (EncType == EncryptionType.AesCbc256_HmacSha256_B64 && Key.Length == 64)
            {
                EncKey = new ArraySegment<byte>(Key, 0, 32).ToArray();
                MacKey = new ArraySegment<byte>(Key, 32, 32).ToArray();
            }
            else
            {
                throw new InvalidKeyOperationException("Unsupported encType/key length.");
            }

            if (Key != null)
            {
                KeyB64 = Convert.ToBase64String(Key);
            }
            if (EncKey != null)
            {
                EncKeyB64 = Convert.ToBase64String(EncKey);
            }
            if (MacKey != null)
            {
                MacKeyB64 = Convert.ToBase64String(MacKey);
            }
        }

        public byte[] Key { get; set; }
        public byte[] EncKey { get; set; }
        public byte[] MacKey { get; set; }
        public EncryptionType EncType { get; set; }
        public string KeyB64 { get; set; }
        public string EncKeyB64 { get; set; }
        public string MacKeyB64 { get; set; }

        public class ArgumentKeyNullException : ArgumentNullException
        {
            public ArgumentKeyNullException(string paramName) : base(paramName)
            {
            }

            public ArgumentKeyNullException(string message, Exception innerException) : base(message, innerException)
            {
            }

            public ArgumentKeyNullException(string paramName, string message) : base(paramName, message)
            {
            }
        }

        public class InvalidKeyOperationException : InvalidOperationException
        {
            public InvalidKeyOperationException(string message) : base(message)
            {
            }

            public InvalidKeyOperationException(string message, Exception innerException) : base(message, innerException)
            {
            }
        }
    }

    public class UserKey : SymmetricCryptoKey
    {
        public UserKey(byte[] key, EncryptionType? encType = null)
            : base(key, encType)
        { }
    }

    public class MasterKey : SymmetricCryptoKey
    {
        public MasterKey(byte[] key, EncryptionType? encType = null)
            : base(key, encType)
        { }
    }

    public class PinKey : SymmetricCryptoKey
    {
        public PinKey(byte[] key, EncryptionType? encType = null)
            : base(key, encType)
        { }
    }

    public class OrgKey : SymmetricCryptoKey
    {
        public OrgKey(byte[] key, EncryptionType? encType = null)
            : base(key, encType)
        { }
    }

    public class CipherKey : SymmetricCryptoKey
    {
        public CipherKey(byte[] key, EncryptionType? encType = null)
            : base(key, encType)
        { }
    }
}