On Friday, March 23, 2018 at 9:11:00 AM UTC-4, Миша Винник wrote: > > Hello third time. > > Totally newbie in C++ and crypto-things. > General schema is here: > https://developers.google.com/pay/api/payment-data-cryptography#encrypt-spec > > Am I right in understanding for what different cryptopp things to be used? > > Short schema of my actions: > > 1)loading keys (PEM keys, I think) from string as here: > > string base64_decode(string encoded) { > string decoded; > > CryptoPP::Base64Decoder decoder; > decoder.Put((CryptoPP::byte*)encoded.data(), encoded.size()); > decoder.MessageEnd(); > > CryptoPP::word64 size = decoder.MaxRetrievable(); > if (size && size <= SIZE_MAX) > { > decoded.resize(size); > decoder.Get((CryptoPP::byte*)&decoded[0], decoded.size()); > return decoded; > } > else { > return ""; > } > } > > string priv_key_encoded = "...";//big things in base64, like this: > // > MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgWV4oK8c/MZkCLk4qSCNjW0Zm6H0CBCtSYxkXkC9FBHehRANCAAQPldOnhO2/oXjdJD1dwlFPiNs6fcdoRgFu3/Z0iKj24SjTGyLRGAtYWLGXBZcDdPj3T2bJRHRVhE8Bc2AjkT7n > string priv_key = base64_decode(priv_key_encoded); > const CryptoPP::byte *priv_key_ptr = (const CryptoPP::byte*) > priv_key.data(); > CryptoPP::SecByteBlock privKey(*priv_key_ptr); > > //similar actions on other keys - our private, accepted ephemeral and > accepted public > > CryptoPP::OID curve = CryptoPP::ASN1::secp256r1(); > CryptoPP::ECDH<CryptoPP::ECP>::Domain dh(curve); > CryptoPP::DH2 dh2(dh); > > //and finally: > dh2.Agree(shared_secret, privKey, ephPrivKey, g_pubKey, g_ephKey, false) > > When I use outer keys auto-generated with GenerateKeyPair, I get > shared_secret, but with Google keys - not. What can it be? Incorrect key > loading? > Google ephemeral is 65-byte length after base64 decoding, but google > public (from here > https://payments.developers.google.com/paymentmethodtoken/keys.json) is > 91-byte length. Tryed to use only last 65 - no effect. >
Man, Google search is getting bad. I could not find the wiki page of interest... Part of the Google Pay problem has been solved at https://www.cryptopp.com/wiki/Elliptic_Curve_Integrated_Encryption_Scheme#Android_Pay_Example . I'm not sure how complete the example is, but I seem to recall it is not complete. Jeff -- You received this message because you are subscribed to "Crypto++ Users". More information about Crypto++ and this group is available at http://www.cryptopp.com and http://groups.google.com/forum/#!forum/cryptopp-users. --- You received this message because you are subscribed to the Google Groups "Crypto++ Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to cryptopp-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
