mirror of
https://github.com/rclone/rclone.git
synced 2024-12-11 11:43:42 +08:00
106 lines
3.9 KiB
Markdown
106 lines
3.9 KiB
Markdown
EME for Go [](https://travis-ci.org/rfjakob/eme) [](https://godoc.org/github.com/rfjakob/eme) 
|
|
==========
|
|
|
|
**EME** (ECB-Mix-ECB or, clearer, **Encrypt-Mix-Encrypt**) is a wide-block
|
|
encryption mode developed by Halevi
|
|
and Rogaway in 2003 [[eme]](#eme).
|
|
|
|
EME uses multiple invocations of a block cipher to construct a new
|
|
cipher of bigger block size (in multiples of 16 bytes, up to 2048 bytes).
|
|
|
|
Quoting from the original [[eme]](#eme) paper:
|
|
|
|
> We describe a block-cipher mode of operation, EME, that turns an n-bit block cipher into
|
|
> a tweakable enciphering scheme that acts on strings of mn bits, where m ∈ [1..n]. The mode is
|
|
> parallelizable, but as serial-efficient as the non-parallelizable mode CMC [6]. EME can be used
|
|
> to solve the disk-sector encryption problem. The algorithm entails two layers of ECB encryption
|
|
> and a “lightweight mixing” in between. We prove EME secure, in the reduction-based sense of
|
|
> modern cryptography.
|
|
|
|
Figure 2 from the [[eme]](#eme) paper shows an overview of the transformation:
|
|
|
|
[![Figure 2 from [eme]](paper-eme-fig2.png)](#)
|
|
|
|
This is an implementation of EME in Go, complete with test vectors from IEEE [[p1619-2]](#p1619-2)
|
|
and Halevi [[eme-32-testvec]](#eme-32-testvec).
|
|
|
|
Is it patentend?
|
|
----------------
|
|
|
|
In 2007, the UC Davis has decided to abandon [[patabandon]](#patabandon)
|
|
the patent application [[patappl]](#patappl) for EME.
|
|
|
|
Related algorithms
|
|
------------------
|
|
|
|
**EME-32** is EME with the cipher set to AES and the length set to 512.
|
|
That is, EME-32 [[eme-32-pdf]](#eme-32-pdf) is a subset of EME.
|
|
|
|
**EME2**, also known as EME\* [[emestar]](#emestar), is an extended version of EME
|
|
that has built-in handling for data that is not a multiple of 16 bytes
|
|
long.
|
|
EME2 has been selected for standardization in IEEE P1619.2 [[p1619.2]](#p1619.2).
|
|
|
|
References
|
|
----------
|
|
|
|
#### [eme]
|
|
*A Parallelizable Enciphering Mode*
|
|
Shai Halevi, Phillip Rogaway, 28 Jul 2003
|
|
https://eprint.iacr.org/2003/147.pdf
|
|
|
|
Note: This is the original EME paper. EME is specified for an arbitrary
|
|
number of block-cipher blocks. EME-32 is a concrete implementation of
|
|
EME with a fixed length of 32 AES blocks.
|
|
|
|
#### [eme-32-email]
|
|
*Re: EME-32-AES with editorial comments*
|
|
Shai Halevi, 07 Jun 2005
|
|
http://grouper.ieee.org/groups/1619/email/msg00310.html
|
|
|
|
#### [eme-32-pdf]
|
|
*Draft Standard for Tweakable Wide-block Encryption*
|
|
Shai Halevi, 02 June 2005
|
|
http://grouper.ieee.org/groups/1619/email/pdf00020.pdf
|
|
|
|
Note: This is the latest version of the EME-32 draft that I could find. It
|
|
includes test vectors and C source code.
|
|
|
|
#### [eme-32-testvec]
|
|
*Re: Test vectors for LRW and EME*
|
|
Shai Halevi, 16 Nov 2004
|
|
http://grouper.ieee.org/groups/1619/email/msg00218.html
|
|
|
|
#### [emestar]
|
|
*EME\*: extending EME to handle arbitrary-length messages with associated data*
|
|
Shai Halevi, 27 May 2004
|
|
https://eprint.iacr.org/2004/125.pdf
|
|
|
|
#### [patabandon]
|
|
*Re: [P1619-2] Non-awareness patent statement made by UC Davis*
|
|
Mat Ball, 26 Nov 2007
|
|
http://grouper.ieee.org/groups/1619/email-2/msg00005.html
|
|
|
|
#### [patappl]
|
|
*Block cipher mode of operation for constructing a wide-blocksize block cipher from a conventional block cipher*
|
|
US patent application US20040131182
|
|
http://www.google.com/patents/US20040131182
|
|
|
|
#### [p1619-2]
|
|
*IEEE P1619.2™/D9 Draft Standard for Wide-Block Encryption for Shared Storage Media*
|
|
IEEE, Dec 2008
|
|
http://siswg.net/index2.php?option=com_docman&task=doc_view&gid=156&Itemid=41
|
|
|
|
Note: This is a draft version. The final version is not freely available
|
|
and must be bought from IEEE.
|
|
|
|
Package Changelog
|
|
-----------------
|
|
|
|
v1.1, 2017-03-05
|
|
* Add eme.New() / \*EMECipher convenience wrapper
|
|
* Improve panic message and parameter wording
|
|
|
|
v1.0, 2015-12-08
|
|
* Stable release
|