I tried to use EVP but let if of go due to bad documentation...

On Wed, Mar 28, 2012 at 2:49 AM, Jakob Bohm <jb-open...@wisemo.com> wrote:

> On 3/27/2012 10:42 PM, Jeffrey Walton wrote:
>
>> On Tue, Mar 27, 2012 at 4:26 PM, Ken Goldman<kgold...@us.ibm.com>  wrote:
>>
>>> On 3/27/2012 3:51 PM, Jakob Bohm wrote:
>>>
>>>> On 3/27/2012 9:37 PM, Dr. Stephen Henson wrote:
>>>>
>>>>> You should really be using EVP instead of the low level routines.
>>>>> They are well documented with examples.
>>>>>
>>>> Where, precisely?
>>>>
>>>> I didn't find it either when I was looking a few years ago, so I
>>>> settled on the obvious low level APIs too.
>>>>
>>> In fact, neither the low level or the EVP APIs are documented.  I don't
>>> see
>>> any AES documentation at all.
>>>
>> Digest (search for "openssl evp digest example"):
>>   
>> http://www.openssl.org/docs/**crypto/EVP_DigestInit.html<http://www.openssl.org/docs/crypto/EVP_DigestInit.html>
>>
> At least this one is outdated, it recommends SHA1, does not
> mention any of the larger algorithms and still shows the
> old SSL MD5+SHA1 288 bit length as the maximum MD size.
>
> openssl/evp.h has later definitions but no documentation in it.
>
> This document also gives two good reason not to use this
> interface when retrofitting existing code:
>
> 1. The state structure (EVP_MD_CTX) requires an extra call to
> free internal memory, which may not fit into existing code
> that doesn't have such a requirement of its own.
>
> 2. The EVP_DigestInit_ex() function is documented as loading
> a specific implementation if NULL is passed, thus almost certainly
> ensuring that said specific implementation will be linked into
> programs that don't use it at all.  It is also unclear how
> referencing a specific engine avoids loading the entire feature
> set of that engine when only a subset is needed.  Such granularity
> issues basic questions one should always consider in any library
> design.
>
>
>  Encrypt (search for "openssl evp encrypt example"):
>>   
>> http://www.openssl.org/docs/**crypto/EVP_EncryptInit.html<http://www.openssl.org/docs/crypto/EVP_EncryptInit.html>
>>
>> Sign  (search for "openssl evp sign example"):
>>   
>> http://www.openssl.org/docs/**crypto/EVP_SignInit.html<http://www.openssl.org/docs/crypto/EVP_SignInit.html>
>>
>> Verify  (search for "openssl evp verify example"):
>>   
>> http://www.openssl.org/docs/**crypto/EVP_VerifyInit.html<http://www.openssl.org/docs/crypto/EVP_VerifyInit.html>
>>
> (I have not checked out those yet).
>
> Explicitly adding the "word" EVP to those searches was
> non-obvious because as a programmer I tend not to consider
> parts of identifiers as separate search words (except when
> doing a raw grep).  And besides, how should a newcomer to
> OpenSSL guess that something called "EVP" is of any
> significance?
>
>
> --
> Jakob Bohm, CIO, partner, WiseMo A/S. http://www.wisemo.com
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