[Qt-interest] Generating RSA-SHA1 signature

[Thiago Macieira]

Em Segunda-feira 27 Setembro 2010, às 20:12:29, Colin S. Miller escreveu:
> Thiago Macieira wrote:
> > On Monday 27. September 2010 09.02.04 dominic.velikakath at nokia.com wrote:
> >> Hi,
> >> 
> >> Does QT provide API's to generate RSA-SHA1 signature.
> > 
> > Not sure what RSA is in that context, but Qt has API to calculate the
> > SHA-1 digest of some data. See QCryptographicHash.
> 
> I assume that the OP is refering to the Rivest, Shamir and Adleman
> asymmetric encryption algorithm. Although they are commonly
> used alongside each other, it is not a hashing algorithm like SHA-1.

Indeed, I know what the RSA algorithm is, but I was trying to understand how 
RSA and SHA-1 fit together. The word "signature" would seem to imply an 
asymmetric-key signing of a block of data. So it seems to me that the OP wants 
to use SHA-1 to create a digest, then encrypt it with an RSA private key.

But it's a weird turn of phrase. If I wanted to know how to do that, I'd ask 
"does Qt provide APIs to sign a block of data using an RSA key" and leave the 
hashing algorithm aside.

> 
> MD5 (another hash) was invested by Rivest alone, but who the inventors
> of SHA-1 where does not seem to be public knowledge, it is credited to the
> NSA. (The USA's national security agency).

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
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