We need to convert the following function into assembly code:
bool RSAVerifyBuffer(const char *pubFilename, const char *messageFilename, const char *signatureFilename)
StringSource pubFile(pubFilename, true, new HexDecoder);
StringSource signatureFile(signatureFilename, true, new HexDecoder);
if ([url removed, login to view]() != [url removed, login to view]())
SecByteBlock signature([url removed, login to view]());
[url removed, login to view](signature, [url removed, login to view]());
VerifierFilter *verifierFilter = new VerifierFilter(pub);
verifierFilter->Put(signature, [url removed, login to view]());
StringSource f(messageFilename, true, verifierFilter);
That code is taken from Crypto++ library (we just changed "FileSource" for "StringResource" to work with buffer instead of files). (Note, there is also "LibTomCrypt" which has the rsa_verify function in C, in case you prefer look into that one instead, though you should also need the SHA function)
We don't require the conversion from that C++ code specifically, that is, we just want the function "RSAVerifyBuffer" implemented in Assembly language (you can copy paste code some IDA disassembled code if you want). If you want to code that function from the scratch (without looking into the above code), that's excellent too.
RSAVerifyBuffer receives 3 arguments:
bool RSAVerifyBuffer(publicKey, msgtoVerify, signature)
publicKey = pointer to public key to verify the buffer
msgToVerify = pointer to message to verify
signature = signature to compare verification
The final solution can be just a command line application compiled with MASM which receives the 3 arguments to pass to RSAVerifyBuffer.
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