Re: message too long for this public key. Was: system.security.cryptography.rsa.toxmlstring

[Wei Dai]

There is indeed an error. Try using the Integer constructor that takes a byte * and a length (i.e., a byte array) as inputs, instead of char * (i.e., zero-terminated C string). ----- Original Message ----- From: Haytham Mohammed To: cryptopp-list@eskimo.com Sent: Wednesday, September 13, 2006 3:37 PM Subject: Re: message too long for this public key. Was: system.security.cryptography.rsa.toxmlstring Hi Mathieu   your function Base64ToInteger is correct, I tested it.   if u tried that line StringSource(mod_sstr, true, new Base64Encoder(new StringSink(result)));   u will found out that is working correctly.   but IntegerToBase64  function returns the wrong result, however I don't see any errors in code.   May be there is another way for using DEREncode function to return the correct results. Regards Haytham Mohammed Mathieu Malaterre <[EMAIL PROTECTED]> wrote: I went one step further and created back the base64 string: void IntegerToBase64(Integer const &xmlint, char *base64String) { std::string result; Base64Encoder enc64(new StringSink(result)); xmlint.DEREncode(enc64); enc64.MessageEnd(); strcpy(base64String, result.c_str()); } And I get: AgQFi3DG which is pretty alarming, but would make sense since 93024454 is not that big of a number. So my guess is that my function Base64ToInteger is incorrect. Mathieu Jeffrey Walton wrote: > Hi Mathieu, > > Here's what I got after adding a sanity check: > Modulus: 93024454 > Exponent: 0 > > Jeff > > CryptoPP::RSA::PublicKey CreatePublicKey() > { > ... > CryptoPP::Integer mod, exp; > Base64ToInteger(modulus, mod); > Base64ToInteger(exponent, exp); > > std::cout << "Modulus: " << mod << std::endl; > std::cout << "Exponent: " << exp << std::endl; > > CryptoPP::RSA::PublicKey key; > } > > On 9/11/06, Mathieu Malaterre <[EMAIL PROTECTED]>wrote: >> Thanks Jeffrey, >> >> Actually what I am trying to do is quite simple. It's just that I >> cannot find the information on internet(*). Here is what I have so far: >> >> void Base64ToInteger(const char *base64String, Integer &xmlint) >> { >> StringSource mod_s( base64String, true, new Base64Decoder); >> unsigned long mrs = mod_s.MaxRetrievable(); >> char* mod_sstr = new char[mrs]; >> mod_s.Get( (unsigned char*)mod_sstr, mrs ); >> xmlint = Integer(mod_sstr); >> delete[] mod_sstr; >> } >> >> RSA::PublicKey CreatePublicKey() >> { >> const char modulus[] = >> "wehzXu32ipNZZkhWqYMVrKoWs4o5AfPKZbdTLVVt8jPfC09yKzC/ajJTeGm87moeU+yZ6Lz8PXsKOmxxNFBE3vQpbMEq++fCjhI0QdC4q/h0H6FePN7MC3WZmR0hpI3yp5sGNfBSBMPNRsnpEGI00ByxQp1N8R9hj9pc0OvwswE="; >> >> const char exponent[] = "AQAB"; >> Integer mod, exp; >> Base64ToInteger(modulus, mod); >> Base64ToInteger(exponent, exp); >> >> RSA::PublicKey key; >> key.Initialize(mod, exp); >> return key; >> } >> >> int main() >> { >> RSA::PublicKey pubKey = CreatePublicKey(); >> const char message[] = "hello"; >> RSAES_OAEP_SHA_Encryptor pub(pubKey); >> AutoSeededRandomPool randPool; >> std::string result; >> StringSource(message, true, new PK_EncryptorFilter(randPool, pub, >> new Base64Encoder(new StringSink(result)))); >> } >> >> All I get is: >> >> terminate called after throwing an instance of >> 'CryptoPP::InvalidArgument' >> what(): RSA/OAEP-MGF1(SHA-1): message too long for this public key >> >> >> All I am trying is do the RSA encryption by setting parameter >> one by >> one, reading each XML elements(**). >> >> Any suggestion ? Thanks >> Mathieu >> >> (*) >> So I found this post by accident. >> http://www.mail-archive.com/cryptopp-list@eskimo.com/msg01619.html >> Indeed if you try to find this post by using keyword like 'SetModulus' >> or 'SetPublicExponent', I cannot find it either by using the internal >> search engine or via google: >> http://www.google.com/search?hl=en&q=SetPublicExponent+site%3Awww.mail-archive.com >> >> >> (**) >> http://www.w3.org/TR/xmldsig-core/#sec-RSAKeyValue >> >> Jeffrey Walton wrote: >> > Hi Mathieu, >> > >> > I would assume you would provide a Cryptographic Sservice Package >> > (CSP). But I've never looked into in. >> > >> >> I am looking to replace the .NET Framework >> >> crypto class by the CryptoPP one. >> > You probably cannot replace the .NET cryptography package per se. You >> > would provide the CSP, and then set it as the machine default CSP. >> > Again, I'm shooting from the hip. >> > >> > Jeff >> > >> > On 9/11/06, Mathieu Malaterre <[EMAIL PROTECTED]>wrote: >> >> Hello, >> >> >> >> I am looking to replace the .NET Framework crypto class by the >> >> CryptoPP >> >> one. Has anyone try doing so ? Could they share there experience ? >> I am >> >> having a hard time understanding how to setup manually all the >> >> parameters (Modulus, Exponent, InverseQ...) are there any examples >> >> somewhere that I can look at ? >> >> Finally the only post I was able to find mentionned a >> problem of >> >> endianness: >> >> >> >> >> http://www.eggheadcafe.com/forumarchives/win32programmerdirectxvideo/dec2005/post24849638.asp >> >> >> >> >> >> >> Is this something that has been solved since ? >> >> >> >> Thanks for your time, >> >> Mathieu >> >> >> >> >> > >> > >> >> > > Get your email and more, right on the new Yahoo.com