On Thu, Apr 20, 2023 at 4:11 PM Dwight Kulkarni <dwi...@realtime-7.com> wrote:
>
> I have two systems, one is running Python and one is running CryptoPP C++.
>
> I create a common certificate that is .DER encoded. I am able to import the
> certificate into both systems. I use the certificate to encrypt and decrypt
> successfully on each system individually.
>
> Then I generate an encrypted message with Crypto++ and send it to Python and
> try to decrypt and it gives an error that decryption failed.
>
> Can you suggest any debugging steps ?
>
> std::string encrypt_rsa(std::string message, CryptoPP::RSA::PublicKey key)
> {
>
> try{
>
> message = b64encode(message);
> CryptoPP::AutoSeededRandomPool rng;
>
> CryptoPP::RSAES_OAEP_SHA_Encryptor encryptor(key);
> std::string ciphertext;
> CryptoPP::StringSource(message, true, new CryptoPP::PK_EncryptorFilter(rng,
> encryptor, new CryptoPP::StringSink(ciphertext)));
> return ciphertext;
> }
> catch(...)
> {
> std::cout << "error encrypting RSA";
> return "";
> }
> }
>
> def encrypt_rsa(message, key):
> try:
> result = rsa.encrypt(base64.b64encode(message), key)
> return result
> except Exception as err:
> print("There was an error encryption RSA", err)
> return None
>
> def decrypt_rsa(cipherbytes, key):
> try:
> base64_bytes = rsa.decrypt(cipherbytes, key)
> return base64.b64decode(base64_bytes)
> except Exception as err:
> print(err)
> return None
I did not consult the Python documentation, so I am shooting from the hip...
Crypto++ RSAES_OAEP_SHA_Encryptor uses SHA1 by default. See
https://www.cryptopp.com/wiki/RSA_Encryption_Schemes .
I'm guessing Python is using SHA-256 or SHA-512.
You should do something like:
typedef RSAES<OAEP<SHA256> >::Encryptor RSAES_OAEP_SHA256_Encryptor;
typedef RSAES<OAEP<SHA256> >::Decryptor RSAES_OAEP_SHA256_Decryptor;
and then use RSAES_OAEP_SHA256_Encryptor and RSAES_OAEP_SHA256_Decryptor.
Or, you can consult the Python documentation and see how to configure
RSA/OAEP to use SHA1.
Jeff
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