MD5

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MD5

Last updated at 10:36 am UTC on 10 June 2017

https://en.wikipedia.org/wiki/MD5
The MD5 algorithm is a widely used hash function producing a 128-bit hash value. Although MD5 was initially designed to be used as a cryptographic hash function, it has been found to suffer from extensive vulnerabilities. It can still be used as a checksum to verify data integrity, but only against unintentional corruption.

Repository

From MonticelloBrowser: http://www.squeaksource.com/Cryptography package Cryptography

MD5 broken

casimiro barreto
<casimiro.barreto@gmail.com>	Wed, Jun 7, 2017 at 9:40 PM
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MD5 (non primitive and with primitive) is broken because it relies on the conversion of Character to SmallInteger so the method shiftBits:

Problem happens at ThirthyTwoBitRegister>>reverseLoadFrom:at:

which is called from MD5NonPrimitive>>proccessBuffer:

Error is: Instance of Character did not understand #bitShift and happened at:

reverseLoadFrom: aByteArray at: index
    "Load my 32-bit value from the four bytes of the given ByteArray
starting at the given index. Consider the first byte to contain the most
significant bits of the word (i.e., use big-endian byte ordering)."

    hi := ((aByteArray at: index + 3) bitShift: 8) + ( aByteArray at: index + 2).
    low := ((aByteArray at: index + 1) bitShift: 8) + ( aByteArray at: index).

Nicolas Cellier


Nicolas Cellier
<nicolas.cellier.aka.nice@gmail.com>	Wed, Jun 7, 2017 at 11:28 PM
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OK,  so which MC version exactly, which image, which VM, which OS, and what step to reproduce? Is it from SqueakMap? a ConfigurationOfCryptography?

If I load in up-to-date trunk spur 32 bits image, for example Cryptography-rww.55 (because it has reasonnable log message),
then test this snippet:

    MD5NonPrimitive hashStream: 'foobar' readStream.

I get a ByteArray answer without failure:

    #[56 88 246 34 48 172 60 145 95 48 12 102 67 18 198 63]

same for
    MD5 new hashMessage: 'foo'

same with latest Cryptography-rww.71...

Casimiro barreto

<casimiro.barreto@gmail.com>	Thu, Jun 8, 2017 at 6:14 PM
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I loaded it in Squeak 6.0 (trunk), Pharo 6.0 (32), Squeak 5.1 all in one, Pharo 5 all in one... All the last versions. Not from ConfigurationOfCryptography (which does not exist in the repository) but http://www.squeaksource.com/Cryptography package is Cryptography-rww.71.mcz but same error is present in Cryptography-acp.70.mcz and olders. Assume it worked in squeak 3.9 & 4 (because I used it at that point with no problems). To reproduce the error just do:

md5hash := MD5 new.
md5hash initializeState.
md5hash processBuffer: 'Casimiro de Almeida Barreto'.
hc := sha256hash finalHash.

and you´ll get the corresponding error & debug needed.

It is not an urgent problem (since nobody is using MD5 anymore) but I just recovered old code that used it and the error appeared. I´m using SHA256 instead and it runs OK. But it is bad to have broken code in the repository.

Best regards,

Casimiro

A new implementation in WebUtils


Levente Uzonyi
<leves@caesar.elte.hu>	Thu, Jun 8, 2017 at 8:13 PM
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On Thu, 8 Jun 2017, casimiro barreto wrote:

    I loaded it in Squeak 6.0 (trunk), Pharo 6.0 (32), Squeak 5.1 all in one, Pharo 5 all in one... All the last versions. Not from ConfigurationOfCryptography (which does not exist in the
    repository) but http://www.squeaksource.com/Cryptography package is Cryptography-rww.71.mcz but same error is present in Cryptography-acp.70.mcz and olders. Assume it worked in squeak 3.9 &
    4 (because I used it at that point with no problems). To reproduce the error just do:

    md5hash := MD5 new.
    md5hash initializeState.
    md5hash processBuffer: 'Casimiro de Almeida Barreto'.


#processBuffer: is a private method, which expects a ByteArray of size 64. A ByteString, or a smaller collection should not and will not work.
The following is expected to produce the correct output:

(MD5 hashMessage: 'Casimiro de Almeida Barreto') hex

In recent images, there's WebUtils, which uses a different MD5 implementation:

WebUtils md5Digest: 'Casimiro de Almeida Barreto'

It uses a plugin shipped with the released VMs, so it's at least 10x faster.

Levente