Trouble to verify ECDSA signature, NIST P-256
gniibe at fsij.org
Mon Nov 26 00:47:31 CET 2018
Yann Garcia <garcia.yann at gmail.com> wrote:
I think this representation is...
> And here was the issue: I got the error message "gcrypt/Not implemented"
... not supported by libgcrypt.
For NIST P-256, only standard encoding (prefixed by 0x04, followed by X
in MPI, then, Y in MPI ) is supported. If not, it results an error
in _gcry_ecc_os2ec by GPG_ERR_NOT_IMPLEMENTED (Not implemented).
Just put the prefix "04" to your representation, if it's composed by X
and Y in big endian.
SEC 1: Elliptic Curve Cryptography (Version 2.0)
2.3.3 Elliptic-Curve-Point-to-Octet-String Conversion
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