[openssl-users] Is it mandatory to reverse windows signature while doing verification in OpenSSL?

[Jeffrey Walton]

> We have signed data on Win 7 using Crypto APIs and generated signature. We
> have observed this signature data needs to be reversed for verification
> using OpenSSL. If we reverse signature data and pass it to OpenSSL
> verification command then OpenSSL verifies it successfully. We wanted to
> confirm, whether such reversing of signature bytes is valid operation or
> not. Thanks in advance.
>
As Tom said, reversing the bytes is quite common when interop'ing with
MS CAPI. See, for example,
http://www.google.com/search?q=ms+capi+reverse+bytes.

For the longest time, it was the only library I was aware that you had
to be mindful of the endian issues. Poly1305 is now a similar island.
Crypto++'s Integer class recently modified to take the little endian
strings and byte arrays for testing straight from Bernstein's
parameters.

Jeff