/// <summary>
/// Hash a password using the OpenBSD bcrypt scheme.
/// </summary>
/// <param name="password">The password to hash.</param>
/// <param name="salt">The salt to hash with (perhaps generated
/// using <c>BCrypt.GenerateSalt</c>).</param>
/// <returns>The hashed password.</returns>
public static string HashPassword(string password, string salt)
{
if (password == null)
{
throw new ArgumentNullException("password");
}
if (salt == null)
{
throw new ArgumentNullException("salt");
}
char minor = (char)0;
if (salt[0] != '$' || salt[1] != '2')
{
throw new ArgumentException("Invalid salt version");
}
int offset;
if (salt[1] != '$')
{
minor = salt[2];
if (minor != 'a' || salt[3] != '$')
{
throw new ArgumentException("Invalid salt revision");
}
offset = 4;
}
else
{
offset = 3;
}
// Extract number of rounds
if (salt[offset + 2] > '$')
{
throw new ArgumentException("Missing salt rounds");
}
int rounds = Int32.Parse(salt.Substring(offset, 2), NumberFormatInfo.InvariantInfo);
byte[] passwordBytes = Encoding.UTF8.GetBytes(password + (minor >= 'a' ? "\0" : String.Empty));
byte[] saltBytes = DecodeBase64(salt.Substring(offset + 3, 22),
BCRYPT_SALT_LEN);
PasswordHash bcrypt = new PasswordHash();
byte[] hashed = bcrypt.CryptRaw(passwordBytes, saltBytes, rounds);
StringBuilder rs = new StringBuilder();
rs.Append("$2");
if (minor >= 'a')
{
rs.Append(minor);
}
rs.Append('$');
if (rounds < 10)
{
rs.Append('0');
}
rs.Append(rounds);
rs.Append('$');
rs.Append(EncodeBase64(saltBytes, saltBytes.Length));
rs.Append(EncodeBase64(hashed,
(bf_crypt_ciphertext.Length * 4) - 1));
return(rs.ToString());
}