Hello Everyone,
I'm fairly new to crypto++, so bare my potentially silly question:
I need to calculate a signature with an eliptic curve dsa scheme,
using SHA-1 hash. The issue is that space for the signature is
limited, so I need to truncate the SHA-1 digest in order to reduce
resulting signature length (yes, I know that the overall resulting
security of the hash is lower, but that is accepted). I have found
some methods in the SHA implementation for that, however I'm stuck on
how I could use this together with ECDSA templates like in the example
below.
ECDSA<ECP, SHA1>::PrivateKey key;
key.Load(...);
ECDSA<ECP,SHA1>::Signer signer(key);
StringSource( message, true,
new SignerFilter( prng,
signer,
new StringSink( signature )
) // SignerFilter
); // StringSource
// signature is always resulting in 28 bytes length for e.g. secp112r1
Can anyone pinpoint me to the right direction? Any examples in how to
calculate this signature with a truncated hash digest, so that the
above signature would result in - say 20 bytes?
Regards
Chris
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