On Wednesday, 4 March 2015 00:43:49 UTC+1, Jeffrey Walton wrote:
>
> >> However how do I construct points q and g)
> >>
> > You should be given G. Its the generator, and its part of the domain
> parameters.
> ?
> > x is the private exponent, and Q is the public key. To generate `x`, you
> > pick a random number in [1, p-1] (IIRC). To get Q, you perform Q = xG
> (IIRC).
>
> It just occurred to me what you may have been asking....
>
> Use the Initialize() that takes a PRNG. The library will generate x and Q
> for you.
>
> If you use the Initialize() that lacks the PRNG, then you have to supply x
> and Q.
>
>
Thanks Jeffrey
I believe the PEM pack s fine, its the .Load function that is throwing the
BERDecode error. I have tried the following all resulting in BERDecode
error on load (experimenting SHA1,SHA224,SHA256 Weak::MD5 etc)
ECDSA<ECP, CryptoPP::SHA>::PublicKey publicKeyDER;
FileSource fs( "my-der.der", true /*pump all*/ );
publicKeyDER.Load( fs );
RandomNumberGenerator prng;
valid = publicKeyDER.Validate( prng, 3 );
Here is the ASN output.
openssl asn1parse -in my-der.der -inform DER -dlimit 16
0:d=0 hl=2 l= 107 cons: SEQUENCE
2:d=1 hl=2 l= 87 cons: SEQUENCE
4:d=2 hl=2 l= 7 prim: OBJECT :id-ecPublicKey
13:d=2 hl=2 l= 76 cons: SEQUENCE
15:d=3 hl=2 l= 1 prim: INTEGER :01
18:d=3 hl=2 l= 26 cons: SEQUENCE
20:d=4 hl=2 l= 7 prim: OBJECT :prime-field
29:d=4 hl=2 l= 15 prim: INTEGER :FFFFFFFFFFFFFFFFFFFFFFFFFDE7
46:d=3 hl=2 l= 6 cons: SEQUENCE
48:d=4 hl=2 l= 1 prim: OCTET STRING
0001 - <SPACES/NULS>
51:d=4 hl=2 l= 1 prim: OCTET STRING
0000 - 03 .
54:d=3 hl=2 l= 15 prim: OCTET STRING
0000 - 02 00 00 00 00 00 00 00-00 00 00 00 00 00 01
...............
71:d=3 hl=2 l= 15 prim: INTEGER
:0100000000000001ECEA551AD837E9
88:d=3 hl=2 l= 1 prim: INTEGER :01
91:d=1 hl=2 l= 16 prim: BIT STRING
0000 - 00 02 XX XX XX XX XX XX-XX XX XX XX XX XX XX XX
........L......[
and also:
Private-Key: (113 bit)
pub:
02:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
Field Type: prime-field
Prime:
00:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:fd:e7
A: 0
B: 3 (0x3)
Generator (compressed):
02:00:00:00:00:00:00:00:00:00:00:00:00:00:01
Order:
01:00:00:00:00:00:00:01:ec:ea:55:1a:d8:37:e9
Cofactor: 1 (0x1)
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