The protocol specification describes this. The implementation in src/modules/rlm_eap/ contains diagrams of the packets it expects to receive.

Alan DeKok.

Thank you Alan, but now I have a new problem. I have been reading the src/modules/rlm_eap/ to understand my problem but I don't find the issue. In TLS establishment, the public key in the server.cert is 128 bytes length. I generate a random string of 46 bytes and the protocol version (TLS 1.0 (0x03, 0x01)) and I use the SSL function RSA_public_encrypt() with server's public key to encrypt the PreMasterSecret. As a result I get a 128 length string. As I send this data to the server, I get a "tls rsa encrypted length is wrong: s3_srvr.c: 1450:" Can anybody please tell me where can be my problem? Here is my code for exemple. void Client_Key_Exchange (SSLData *ClientSSLData, unsigned short *length, char *HandshakeMessages, unsigned short *length_Hndshk, char *buff) { char *PreMasterSecret = (char*) _MEMORY_Allocate (58 , true); char *EncryptedPreMasterSecret = (char*) _MEMORY_Allocate (128, true); char *temp = (char*) _MEMORY_Allocate (58 , true); unsigned char *tmpCert = _MEMORY_Allocate (ClientSSLData->certificate_len + 128, true); _RANDOM_MakeCharString (temp, 46); PreMasterSecret [0] = 0x03; PreMasterSecret [1] = 0x01; for (register int i = 0; i<46; i++) { PreMasterSecret[i+2] = temp [i]; ClientSSLData->PreMasterSecret[i] = PreMasterSecret[i]; } for (i = 0; i < ClientSSLData->certificate_len; i++) tmpCert[i] =(unsigned char) ClientSSLData->certificate[i]; //----- OpenSSL Functions ----- RSA *server_public_key; X509 *cert = X509_new (); EVP_PKEY *evp = EVP_PKEY_new (); X509 *err = d2i_X509 (&cert, (unsigned char**) &tmpCert, (ClientSSLData->certificate_len) ); //----- d2i_509 Function retrives tmpCert pointer advanced the number of bytes read ----- tmpCert = tmpCert - (ClientSSLData->certificate_len); //----- We get the public key from the Server certificate ----- evp = X509_get_pubkey(cert); server_public_key = (RSA *) evp->pkey.ptr; int rsasize = RSA_size(server_public_key); //----- We get the PreMasterSecret encrypted ----- int Encrypted_len = RSA_public_encrypt(48, (BYTE*) PreMasterSecret, (unsigned char*)EncryptedPreMasterSecret, server_public_key, RSA_PKCS1_PADDING); ClientSSLData->bufferSSL[(*length)++] = 0x16; // Handshake Message ClientSSLData->bufferSSL[(*length)++] = 0x03; // Version ClientSSLData->bufferSSL[(*length)++] = 0x01; // Version ClientSSLData->bufferSSL[(*length)++] = (Encrypted_len + 6) / 256; // Length ClientSSLData->bufferSSL[(*length)++] = (Encrypted_len + 6) % 256; // Length ClientSSLData->bufferSSL[(*length)++] = 0x10; // Client key exchange ClientSSLData->bufferSSL[(*length)++] = 0x00; // Length ClientSSLData->bufferSSL[(*length)++] = (Encrypted_len ) / 256; // Length ClientSSLData->bufferSSL[(*length)++] = (Encrypted_len ) % 256; // Length //----- Public key exchange ----- for (i = 0; i < Encrypted_len; i++) { buff[i] = EncryptedPreMasterSecret[i]; HandshakeMessages[(*length_Hndshk)++] = EncryptedPreMasterSecret[i]; } free (PreMasterSecret); free (EncryptedPreMasterSecret); free (temp); free (tmpCert); } Thank you for your help. Juan Daniel MORENO