ASP.NET MembershipProvider uses passwordSalt when encrypting - encryption

Question

I've a question about the ASP.NET Membership (from .NET 2.0), and more specifically the way it encrypts passwords (when you choose to encrypt them, and not hash then), and the way it verifies them.
I was under the impression that a password salt would only make sense if you choose to hash your passwords, and not encrypt them. And, according to the MSDN documentation on those old-school membership providers
PasswordSalt nvarchar(128) Randomly generated 128-bit value used to salt password hashes; stored in base-64-encoded form
But, I've tried changing the salt for a password that's stored as encrypted, and validation of that password stopped working (the encrypted password was not changed, just the passwordsalt).
So, is the passwordSalt involved when encrypting/validating the password using those membership providers (since validation stopped working, I'd say it is, but I've no idea why)?
Thanks, and all the best.
EDIT:
I've tried inputting an invalid base64 salt, and got this stacktrace, which is already a bit weird in my opinion, for an encryption check. It looks more like a hash check. Weird thing is none of this is documented on MSDN.
[FormatException: Invalid length for a Base-64 char array or string.]
System.Convert.FromBase64_Decode(Char* startInputPtr, Int32 inputLength, Byte* startDestPtr, Int32 destLength) [phone]
System.Convert.FromBase64CharPtr(Char* inputPtr, Int32 inputLength) +162
System.Convert.FromBase64String(String s) +56
System.Web.Security.SqlMembershipProvider.EncodePassword(String pass, Int32 passwordFormat, String salt) +148
System.Web.Security.SqlMembershipProvider.CheckPassword(String username, String password, Boolean updateLastLoginActivityDate, Boolean failIfNotApproved, String& salt, Int32& passwordFormat) +245
System.Web.Security.SqlMembershipProvider.ValidateUser(String username, String password) +195

Answer 1

I've managed to step-into the System.Web.dll and found the cause.
Apparently, the MSDN documentation is not up to the with the implementation.
In case encryption is selected, apparently it does use the salt.
private string EncodePassword(string pass, int passwordFormat, string salt)
{
byte[] bIn = Encoding.Unicode.GetBytes(pass);
byte[] bSalt = Convert.FromBase64String(salt);
byte[] bRet = null;
...
byte[] bAll = new byte[bSalt.Length + bIn.Length];
Buffer.BlockCopy(bSalt, 0, bAll, 0, bSalt.Length);
Buffer.BlockCopy(bIn, 0, bAll, bSalt.Length, bIn.Length);
bRet = EncryptPassword(bAll, _LegacyPasswordCompatibilityMode);
}