FFI blowfish for encrypting / decrypting [WAS] Re: [Pharo-dev] How to encrypt a password?

Mariano Martinez Peck wrote

> Hi Paul, and just to be sure I understand...none of them could work as a
> two-way encryption, right?
> The only one is your Pharo's version of Blowfish but that only works with
> 8
> chars long. Is it like this? Or is there any other two-way encryption?
>
> Thanks!
>

> --
> Mariano
> http://marianopeck.wordpress.com


Yes that's right.  The PasswordHashingFFI stuff is all one way encryption.
Blowfish is two way, and the current implementation only works for 8 byte
chunks.  I stopped working on it when the Smalltalk bcrypt implementation I
wanted proved to be 5000x times slower than the FFI version. Someone needs
to add the CBC part to Blowfish to encrypt longer strings.  I do not know of
another in image two way encryption scheme, but there may be something in
the Cryptography repo.  I'm not sure.

Hi Mariano,

 

Before I give you an answer, you should never ever ever not even for any reason, ever, did I mention ever, store a user’s password.  You can hash a password, which means you store the hash value of the password.  You can make it more secure by salting the hash or embedding your own key to the hash, or doing a number of other things.  But you should always store an encrypted hash and never a recoverable password.  The way this works is that your user knows the password and can generate a hash at any time that you can compare.  You store the hash of the password to compare.  The reason for this should be obvious.  You don’t want anyone to have access to that password.  Not even programmers.  Your program doesn’t need it either since the user can generate that hash for you at any time.  It really is all you ever need to store.

 

If you are looking for a simple cypher for something other than a password how about ARC4 from www.squeaksrouce.com/Cryptography

 

|key cText pText|

key := SecureRandom picker nextBits: 254.

cText := (ARC4 new key: key) encrypt: 'This is a very secure but meaningless string' asByteArray.

pText := (ARC4 new key: key) decrypt: cText.

^pText asString

'This is a very secure but meaningless string'

 

It’s pretty simple.  To get the plainText back all you need is the key. 

 

All the best,

 

Ron Teitelbaum

 

From: Pharo-dev [mailto:[hidden email]] On Behalf Of Mariano Martinez Peck
Sent: Monday, February 17, 2014 4:17 PM
To: Pharo Development List; [hidden email]; The general-purpose Squeak developers list
Subject: [Pharo-dev] FFI blowfish for encrypting / decrypting [WAS] Re: How to encrypt a password?

 

 

On Thu, Nov 21, 2013 at 3:53 PM, Paul DeBruicker <[hidden email]> wrote:

Mariano Martinez Peck wrote

> Hi Paul, and just to be sure I understand...none of them could work as a
> two-way encryption, right?
> The only one is your Pharo's version of Blowfish but that only works with
> 8
> chars long. Is it like this? Or is there any other two-way encryption?
>
> Thanks!
>

> --
> Mariano
> http://marianopeck.wordpress.com


Yes that's right.  The PasswordHashingFFI stuff is all one way encryption.
Blowfish is two way, and the current implementation only works for 8 byte
chunks.  I stopped working on it when the Smalltalk bcrypt implementation I
wanted proved to be 5000x times slower than the FFI version. Someone needs
to add the CBC part to Blowfish to encrypt longer strings.  I do not know of
another in image two way encryption scheme, but there may be something in
the Cryptography repo.  I'm not sure.

 

Hi Paul,

 

Sorry for the cross posting. 

 

I was using the Smalltalk version of the Blowfish you did to encrypt and decrypt things. But now I realize it is very very slow for the usage I need. You seem to have faced the same problem. 

 

I am encrypting pieces of 8 characters long. But I wonder if the decryption is available as well in FFI version? I see #ffiCrypt:with:   but nothing to decrypt...

 

Thanks in advance 

 

--
Mariano
http://marianopeck.wordpress.com

On Mon, Feb 17, 2014 at 7:25 PM, Ron Teitelbaum <[hidden email]> wrote:

Hi Mariano,

 

Before I give you an answer, you should never ever ever not even for any reason, ever, did I mention ever, store a user’s password.  You can hash a password, which means you store the hash value of the password.  You can make it more secure by salting the hash or embedding your own key to the hash, or doing a number of other things.  But you should always store an encrypted hash and never a recoverable password.  The way this works is that your user knows the password and can generate a hash at any time that you can compare.  You store the hash of the password to compare.  The reason for this should be obvious.  You don’t want anyone to have access to that password.  Not even programmers.  Your program doesn’t need it either since the user can generate that hash for you at any time.  It really is all you ever need to store.

 

Hi Ron,

Thanks for the advice. I have been warned about this in the past so I am NOT using this for storing passwords. Instead, there are instVars from certain objects that are "password protected" because they represent some sensible data. So these fields need to be encrypted/decrypted. The user needs to supply a password for editing/viewing them. These fields were encrypted/decrypted with Blowfish. And the key for the blowfish is the " SecureHashAlgorithm new hashMessage: aString" of the password used to protect them...

Anyway.... I do need encrypt/decrypt and it should be fast. I have just tried ARC4 and seems to be fast. I have a few questions:

- If I make the ARC4 key larger is it likely to be safer? 

- How does ARC4 compare to blowfish from security point of view? Is blowfish much more secure or not that much?

 

Thanks in advance!

If you are looking for a simple cypher for something other than a password how about ARC4 from www.squeaksrouce.com/Cryptography

 

|key cText pText|

key := SecureRandom picker nextBits: 254.

cText := (ARC4 new key: key) encrypt: 'This is a very secure but meaningless string' asByteArray.

pText := (ARC4 new key: key) decrypt: cText.

^pText asString

'This is a very secure but meaningless string'

 

It’s pretty simple.  To get the plainText back all you need is the key. 

 

All the best,

 

Ron Teitelbaum

 

From: Pharo-dev [mailto:[hidden email]] On Behalf Of Mariano Martinez Peck
Sent: Monday, February 17, 2014 4:17 PM
To: Pharo Development List; [hidden email]; The general-purpose Squeak developers list
Subject: [Pharo-dev] FFI blowfish for encrypting / decrypting [WAS] Re: How to encrypt a password?

 

 

On Thu, Nov 21, 2013 at 3:53 PM, Paul DeBruicker <[hidden email]> wrote:

Mariano Martinez Peck wrote

> Hi Paul, and just to be sure I understand...none of them could work as a
> two-way encryption, right?
> The only one is your Pharo's version of Blowfish but that only works with
> 8
> chars long. Is it like this? Or is there any other two-way encryption?
>
> Thanks!
>

> --
> Mariano
> http://marianopeck.wordpress.com


Yes that's right.  The PasswordHashingFFI stuff is all one way encryption.
Blowfish is two way, and the current implementation only works for 8 byte
chunks.  I stopped working on it when the Smalltalk bcrypt implementation I
wanted proved to be 5000x times slower than the FFI version. Someone needs
to add the CBC part to Blowfish to encrypt longer strings.  I do not know of
another in image two way encryption scheme, but there may be something in
the Cryptography repo.  I'm not sure.

 

Hi Paul,

 

Sorry for the cross posting. 

 

I was using the Smalltalk version of the Blowfish you did to encrypt and decrypt things. But now I realize it is very very slow for the usage I need. You seem to have faced the same problem. 

 

I am encrypting pieces of 8 characters long. But I wonder if the decryption is available as well in FFI version? I see #ffiCrypt:with:   but nothing to decrypt...

 

Thanks in advance 

 

--
Mariano
http://marianopeck.wordpress.com

--
Mariano
http://marianopeck.wordpress.com

With stream ciphers (or block cipher in modes that emulate a stream cipher, e.g. OFB, CTR) you absolutely must not reuse the same key to encrypt different data (http://en.wikipedia.org/wiki/Stream_cipher_attack). You could try to devise a way to avoid re-using the exact same key, e.g. generate the encryption key by mixing in a unique id of the field that you're encrypting along with the password, but unless you really know what you're doing, it's quite easy to make a fatal mistake in your design. Best way to do this is to stick with standard solutions. You're trying to use passwords for encryption, so your standard options would be PKCS#5, bcrypt or scrypt.