using System.Management;

namespace WinForms
{
    public class BitLocker
    {
        private readonly string _computerIp;

        public BitLocker(string computerIp)
        {
            _computerIp = computerIp;
        }

        /// <summary>
        /// Simple Usage for localhost:
        /// var bitlocker = new BitLocker("localhost");
        /// var result = bitlocker.UnlockWithPassphrase("D:", "password");
        /// </summary>
        /// <param name="driveLetter"></param>
        /// <param name="passphrase"></param>
        /// <returns></returns>

        public object UnlockWithPassphrase(string driveLetter, string passphrase)
        {
            object result = null;
            const string wmiNamespace = "\\\\{0}\\root\\CIMV2\\Security\\MicrosoftVolumeEncryption";
            var scope = new ManagementScope(string.Format(wmiNamespace, _computerIp));

            var query = new ObjectQuery("SELECT * FROM Win32_EncryptableVolume");
            var searcher = new ManagementObjectSearcher(scope, query);

            var allVolumes = searcher.Get();
            foreach (var o in allVolumes)
            {
                var volume = (ManagementObject) o;
                if (volume.Properties["DriveLetter"].Value.ToString() != driveLetter) continue;
                object[] methodArgs = { passphrase };
                result = volume.InvokeMethod("UnlockWithPassphrase", methodArgs);
            }
            return result;
        }
    }
}

请注意，它需要管理员权限。