> Dear all,
>
> I am a bit confuse with hashing and Digitaly sign data.
> I have understand that hashing a file with a keyed Hash class, you are
> protecting hash value to be modified becasue it is regenerated with a
> secret
> key exanged between the sender and receiver. The receiver will then
> trust the
> sender about the source of the information
> Now I have check the Digital Signature feature which is doing similar
> thing
> except I understand that it add one more level which is the signature
> which
> wrapp the encrypted data and the hash.
> I have read that signature prove also that data has been generated and
> issue
> by a trust sender... Similar as a keyed hash then
> What is the benfits then to sign if Keye hasing get same result ?
>
> thnaks for help
> regards
> serge

"Dominick Baier" wrote:

> The underlying key types and crypto technologies are different.
>
> HMACS are typically used with symmetric keys (typically a 1-1 relationship
> between sender and receiver using a shared key)
> DSIGs are typcially used with asymmetric keys (a 1-n relationship, one can
> form a DSIG, everybody with access to the pub key can verify it)
>
> dominick
> www.leastprivilege.com
>
> > Dear all,
> >
> > I am a bit confuse with hashing and Digitaly sign data.
> > I have understand that hashing a file with a keyed Hash class, you are
> > protecting hash value to be modified becasue it is regenerated with a
> > secret
> > key exanged between the sender and receiver. The receiver will then
> > trust the
> > sender about the source of the information
> > Now I have check the Digital Signature feature which is doing similar
> > thing
> > except I understand that it add one more level which is the signature
> > which
> > wrapp the encrypted data and the hash.
> > I have read that signature prove also that data has been generated and
> > issue
> > by a trust sender... Similar as a keyed hash then
> > What is the benfits then to sign if Keye hasing get same result ?
> >
> > thnaks for help
> > regards
> > serge
>
>
>

"Dominick Baier" wrote:

> The underlying key types and crypto technologies are different.
>
> HMACS are typically used with symmetric keys (typically a 1-1 relationship
> between sender and receiver using a shared key)
> DSIGs are typcially used with asymmetric keys (a 1-n relationship, one can
> form a DSIG, everybody with access to the pub key can verify it)
>
> dominick
> www.leastprivilege.com
>
> > Dear all,
> >
> > I am a bit confuse with hashing and Digitaly sign data.
> > I have understand that hashing a file with a keyed Hash class, you are
> > protecting hash value to be modified becasue it is regenerated with a
> > secret
> > key exanged between the sender and receiver. The receiver will then
> > trust the
> > sender about the source of the information
> > Now I have check the Digital Signature feature which is doing similar
> > thing
> > except I understand that it add one more level which is the signature
> > which
> > wrapp the encrypted data and the hash.
> > I have read that signature prove also that data has been generated and
> > issue
> > by a trust sender... Similar as a keyed hash then
> > What is the benfits then to sign if Keye hasing get same result ?
> >
> > thnaks for help
> > regards
> > serge
>
>
>

> In which form in that case everybody can access the public key then ?
> If you wnat that everybody can verify a file signature, everybody
> should
> know how it has been build no ?
> For example if I signe a file with that way :
>
> Dim signer as RSACryptoServiceProvider= new RSACryptoServiceProvider
> signer.SignData(Data, new SHA1CryptoServiceProvider)
>
> Then for verify the signature I need to use
> signer.VerfyData(Data, new SHA1CryptoServiceProvider, signature)
> or can it be so that as long as you provide a signature and a file,
> any application have enough information to verify it ?
>
> thnaks fro help
> "Dominick Baier" wrote:
>> The underlying key types and crypto technologies are different.
>>
>> HMACS are typically used with symmetric keys (typically a 1-1
>> relationship
>> between sender and receiver using a shared key)
>> DSIGs are typcially used with asymmetric keys (a 1-n relationship,
>> one can
>> form a DSIG, everybody with access to the pub key can verify it)
>> dominick
>> www.leastprivilege.com
>>> Dear all,
>>>
>>> I am a bit confuse with hashing and Digitaly sign data.
>>> I have understand that hashing a file with a keyed Hash class, you
>>> are
>>> protecting hash value to be modified becasue it is regenerated with
>>> a
>>> secret
>>> key exanged between the sender and receiver. The receiver will then
>>> trust the
>>> sender about the source of the information
>>> Now I have check the Digital Signature feature which is doing
>>> similar
>>> thing
>>> except I understand that it add one more level which is the
>>> signature
>>> which
>>> wrapp the encrypted data and the hash.
>>> I have read that signature prove also that data has been generated
>>> and
>>> issue
>>> by a trust sender... Similar as a keyed hash then
>>> What is the benfits then to sign if Keye hasing get same result ?
>>> thnaks for help
>>> regards
>>> serge

"Dominick Baier" wrote:

> For DSIGs you usually use certificates. They add authentication to public
> keys. Otherwise it is not possible to verify that you are really using the
> right public key (besides you received the pub key using an out of band method
> like on a CD, verbal or a fax etc).
>
> Certs can be made available in various ways - e.g. you can embed them in
> the signature, make them downloadable and so forth.
>
> Have a look at the System.Security.Cryptography.X509Certificates and Pkcs
> namespace - here's also a sample app that does signing/encryption using certs:
> http://www.leastprivilege.com/CrypterPKRTMVersion.aspx
>
>
> dominick
>
> > In which form in that case everybody can access the public key then ?
> > If you wnat that everybody can verify a file signature, everybody
> > should
> > know how it has been build no ?
> > For example if I signe a file with that way :
> >
> > Dim signer as RSACryptoServiceProvider= new RSACryptoServiceProvider
> > signer.SignData(Data, new SHA1CryptoServiceProvider)
> >
> > Then for verify the signature I need to use
> > signer.VerfyData(Data, new SHA1CryptoServiceProvider, signature)
> > or can it be so that as long as you provide a signature and a file,
> > any application have enough information to verify it ?
> >
> > thnaks fro help
> > "Dominick Baier" wrote:
> >> The underlying key types and crypto technologies are different.
> >>
> >> HMACS are typically used with symmetric keys (typically a 1-1
> >> relationship
> >> between sender and receiver using a shared key)
> >> DSIGs are typcially used with asymmetric keys (a 1-n relationship,
> >> one can
> >> form a DSIG, everybody with access to the pub key can verify it)
> >> dominick
> >> www.leastprivilege.com
> >>> Dear all,
> >>>
> >>> I am a bit confuse with hashing and Digitaly sign data.
> >>> I have understand that hashing a file with a keyed Hash class, you
> >>> are
> >>> protecting hash value to be modified becasue it is regenerated with
> >>> a
> >>> secret
> >>> key exanged between the sender and receiver. The receiver will then
> >>> trust the
> >>> sender about the source of the information
> >>> Now I have check the Digital Signature feature which is doing
> >>> similar
> >>> thing
> >>> except I understand that it add one more level which is the
> >>> signature
> >>> which
> >>> wrapp the encrypted data and the hash.
> >>> I have read that signature prove also that data has been generated
> >>> and
> >>> issue
> >>> by a trust sender... Similar as a keyed hash then
> >>> What is the benfits then to sign if Keye hasing get same result ?
> >>> thnaks for help
> >>> regards
> >>> serge
>
>
>

> What I have heard and read about certificate is that it require
> maintenance, might need also PKI...
>
> How is it then in real life, does company requring signing are all
> directed to Certificated and CA like Verisign ?
>
> "Dominick Baier" wrote:
>
>> For DSIGs you usually use certificates. They add authentication to
>> public keys. Otherwise it is not possible to verify that you are
>> really using the right public key (besides you received the pub key
>> using an out of band method like on a CD, verbal or a fax etc).
>>
>> Certs can be made available in various ways - e.g. you can embed them
>> in the signature, make them downloadable and so forth.
>>
>> Have a look at the System.Security.Cryptography.X509Certificates and
>> Pkcs namespace - here's also a sample app that does
>> signing/encryption using certs:
>> http://www.leastprivilege.com/CrypterPKRTMVersion.aspx
>>
>> dominick
>>
>>> In which form in that case everybody can access the public key then
>>> ?
>>> If you wnat that everybody can verify a file signature, everybody
>>> should
>>> know how it has been build no ?
>>> For example if I signe a file with that way :
>>> Dim signer as RSACryptoServiceProvider= new RSACryptoServiceProvider
>>> signer.SignData(Data, new SHA1CryptoServiceProvider)
>>>
>>> Then for verify the signature I need to use
>>> signer.VerfyData(Data, new SHA1CryptoServiceProvider, signature)
>>> or can it be so that as long as you provide a signature and a file,
>>> any application have enough information to verify it ?
>>> thnaks fro help
>>> "Dominick Baier" wrote:
>>>> The underlying key types and crypto technologies are different.
>>>>
>>>> HMACS are typically used with symmetric keys (typically a 1-1
>>>> relationship
>>>> between sender and receiver using a shared key)
>>>> DSIGs are typcially used with asymmetric keys (a 1-n relationship,
>>>> one can
>>>> form a DSIG, everybody with access to the pub key can verify it)
>>>> dominick
>>>> www.leastprivilege.com
>>>>> Dear all,
>>>>>
>>>>> I am a bit confuse with hashing and Digitaly sign data.
>>>>> I have understand that hashing a file with a keyed Hash class, you
>>>>> are
>>>>> protecting hash value to be modified becasue it is regenerated
>>>>> with
>>>>> a
>>>>> secret
>>>>> key exanged between the sender and receiver. The receiver will
>>>>> then
>>>>> trust the
>>>>> sender about the source of the information
>>>>> Now I have check the Digital Signature feature which is doing
>>>>> similar
>>>>> thing
>>>>> except I understand that it add one more level which is the
>>>>> signature
>>>>> which
>>>>> wrapp the encrypted data and the hash.
>>>>> I have read that signature prove also that data has been generated
>>>>> and
>>>>> issue
>>>>> by a trust sender... Similar as a keyed hash then
>>>>> What is the benfits then to sign if Keye hasing get same result ?
>>>>> thnaks for help
>>>>> regards
>>>>> serge