首先，你得安装openssl，去官网下载最新版本就行，
安装完成后用命令行打开到openssl安装目录，先生成私钥，私钥保存到此目录的private.pem中，密钥长度2048位，然后再从私钥中提取公钥，公钥保存到此目录的public.pem中，当然，文件名称自己定。
按照上述命令生成好私钥公钥文件后，直接编辑打开把密钥复制出来用，或者在程序中直接用公钥私钥文件加载RSA对象。
QT中数据类型转换还是很不好搞的，下面代码中，密钥，明文，密文我都用的QString作为参数传入，分片加密和解密都有，也是我在项目中使用的版本，我刚学QT不就，如果各位发现我写的有问题的地方，请指正。
代码：
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/bn.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
#include "openssl/ssl.h"
#include "openssl/err.h"
/**
* @brief RSASignature::createRSA 载入密钥
* @param key 密钥
* @param publi 公钥1 私钥0
* @return
*/
RSA * RSASignature::createRSA(unsigned char * key,int publi)
{
RSA *rsa= NULL;
BIO *keybio ;
keybio = BIO_new_mem_buf(key, -1);
if (keybio==NULL)
{
qDebug()<< "Failed to create key BIO";
return 0;
}
if(publi)
{
rsa = PEM_read_bio_RSA_PUBKEY(keybio, &rsa,NULL, NULL);
}
else
{
rsa = PEM_read_bio_RSAPrivateKey(keybio, &rsa,NULL, NULL);
}
if(rsa == NULL)
{
qDebug()<< "Failed to create RSA";
}
return rsa;
}
/**
* @brief RSASignature::public_encrypt 公钥加密
* @param data 待加密数据
* @param data_len 待加密的数据长度
* @param key 公钥
* @param encrypted 加密后的数据
* @return 加密长度
*/
int RSASignature::public_encrypt(unsigned char * data,int data_len,unsigned char * key, unsigned char *encrypted)
{
RSA * rsa = createRSA(key,1);
if(rsa==NULL)
return 0;
result = RSA_public_encrypt(data_len,data,encrypted,rsa,padding);
return result;
}
/**
* @brief RSASignature::private_decrypt 私钥解密
* @param enc_data 待解密数据
* @param data_len 待解密数据长度
* @param key 私钥
* @param decrypted 解密后的数据
* @return
*/
int RSASignature::private_decrypt(unsigned char * enc_data,int data_len,unsigned char * key, unsigned char *decrypted)
{
RSA * rsa = createRSA(key,0);
if(rsa==NULL)
return 0;
int result = RSA_private_decrypt(data_len,enc_data,decrypted,rsa,padding);
return result;
}
/**
* @brief RSASignature::private_encrypt 私钥加密
* @param data 待加密数据
* @param data_len 待加密数据长度
* @param key 私钥
* @param encrypted 加密后数据
* @return
*/
int RSASignature::private_encrypt(unsigned char * data,int data_len,unsigned char * key, unsigned char *encrypted)
{
RSA * rsa = createRSA(key,0);
if(rsa==NULL)
return 0;
qDebug()<<RSA_size(rsa);
int result = RSA_private_encrypt(data_len,data,encrypted,rsa,padding);
return result;
}
/**
* @brief RSASignature::public_decrypt 公钥解密
* @param enc_data 待解密数据
* @param data_len 待解密数据长度
* @param key 公钥
* @param decrypted 解密后的数据
* @return
*/
int RSASignature::public_decrypt(unsigned char * enc_data,int data_len,unsigned char * key, unsigned char *decrypted)
{
RSA * rsa = createRSA(key,1);
if(rsa==NULL)
return 0;
qDebug()<<RSA_size(rsa);
int result = RSA_public_decrypt(data_len,enc_data,decrypted,rsa,padding);
return result;
}
/**
* @brief RSASignature::public_encrypt 公钥加密
* @param data 待加密数据
* @param keystr 公钥
* @param encrypted 加密后数据
* @return
*/
int RSASignature::public_encrypt(QString &data,QString &keystr,QString &encrypted)
{
QByteArray keydata=keystr.toLocal8Bit();
unsigned char *key= (unsigned char*)strdup(keydata.constData());//密钥
RSA * rsa = createRSA(key,1);
if(rsa==NULL)
return 0;
free(key);
int rsasize=RSA_size(rsa);
int exppadding=rsasize;
int result=-1;
QByteArray decdata=QByteArray::fromStdString(data.toStdString()).toBase64(QByteArray::Base64Encoding);
QByteArray signByteArray;
int data_len=decdata.length();
if(data_len>exppadding-11)
exppadding=exppadding-11;
int b=0;
int s=data_len/(exppadding);//片数
if(data_len%(exppadding))
s++;
for(int i=0;i<s;i++)
{
QByteArray subdata={0};
for(int j=0;j<exppadding;j++)
{
if(i*exppadding+j>data_len)
break;
subdata[j]=decdata[j+i*exppadding];
}
unsigned char *smldata=(unsigned char*)strdup(subdata.constData());//数据分片
unsigned char smlencrypted[1024]={0};//片段加密数据
b +=RSA_public_encrypt(exppadding,smldata,smlencrypted,rsa,padding);
if(b>0)
{
QByteArray subarray=QByteArray::fromRawData((const char *)smlencrypted,rsasize);
signByteArray.append(subarray);
}
free(smldata);
}
QString str(signByteArray.toHex());
qDebug()<<str;
encrypted.append(str);
result=b;
return result;
}
/**
* @brief RSASignature::private_decrypt 私钥解密
* @param data 待解密数据
* @param keystr 私钥
* @param decrypted 解密后的数据
* @return
*/
int RSASignature::private_decrypt(QString &data,QString &keystr,QString &decrypted)
{
QByteArray keydata=keystr.toLocal8Bit();
unsigned char *key= (unsigned char*)strdup(keydata.constData());//密钥
RSA * rsa = createRSA(key,0);
if(rsa==NULL)
return 0;
free(key);
int rsasize=RSA_size(rsa);
int result=-1;
QByteArray encdata=QByteArray::fromHex(QByteArray::fromStdString( data.toStdString()));
QByteArray signByteArray;
int data_len=encdata.length();
int b=0;
int s=data_len/(rsasize);//片数
if(data_len%(rsasize))
s++;
for(int i=0;i<s;i++)
{
QByteArray subdata={0};
for(int j=0;j<rsasize;j++)
{
if(i*rsasize+j>data_len)
break;
subdata[j]=encdata[j+i*rsasize];
}
unsigned char *smldata=(unsigned char*)subdata.data();//(unsigned char*)strdup(subdata.constData());//数据分片
unsigned char smlencrypted[1024]={0};//片段加密数据
b +=RSA_private_decrypt(rsasize,smldata,smlencrypted,rsa,padding);
if(b>0)
{
QByteArray decdata((char*)smlencrypted);
signByteArray.append(decdata);
}
}
QByteArray b1= QByteArray::fromBase64(signByteArray,QByteArray::Base64Encoding);
std::string str=b1.toStdString();
decrypted.append(QString::fromStdString( str));
result=b;
return result;
}
/**
* @brief RSASignature::private_encrypt 私钥加密
* @param data 待加密数据
* @param keystr 私钥
* @param encrypted 解密后的数据
* @return
*/
int RSASignature::private_encrypt(QString &data,QString &keystr,QString &encrypted)
{
QByteArray keydata=keystr.toLocal8Bit();
unsigned char *key= (unsigned char*)strdup(keydata.constData());//密钥
RSA * rsa = createRSA(key,0);
if(rsa==NULL)
return 0;
free(key);
int rsasize=RSA_size(rsa);
int exppadding=rsasize;
int result=-1;
QByteArray decdata=QByteArray::fromStdString(data.toStdString()).toBase64(QByteArray::Base64Encoding);
QByteArray signByteArray;
int data_len=decdata.length();
if(data_len>exppadding-11)//padding占11位
exppadding=exppadding-11;
int b=0;
int s=data_len/(exppadding);//片数
if(data_len%(exppadding))
s++;
for(int i=0;i<s;i++)
{
//分片加密
QByteArray subdata={0};
for(int j=0;j<exppadding;j++)
{
if(i*exppadding+j>data_len)
break;
subdata[j]=decdata[j+i*exppadding];
}
unsigned char *smldata=(unsigned char*)strdup(subdata.constData());//数据分片
unsigned char smlencrypted[1024]={0};//片段加密数据
b +=RSA_private_encrypt(exppadding,smldata,smlencrypted,rsa,padding);
if(b>0)
{
QByteArray subarray=QByteArray::fromRawData((const char *)smlencrypted,rsasize);
signByteArray.append(subarray);
}
free(smldata);
}
QString str(signByteArray.toHex());
qDebug()<<str;
encrypted.append(str);
result=b;
return result;
}
/**
* @brief RSASignature::public_decrypt 公钥解密
* @param data 待解密数据
* @param keystr 公钥
* @param decrypted 解密后的数据
* @return
*/
int RSASignature::public_decrypt(QString &data,QString &keystr,QString &decrypted)
{
QByteArray keydata=keystr.toLocal8Bit();
unsigned char *key= (unsigned char*)strdup(keydata.constData());//密钥
RSA * rsa = createRSA(key,1);
if(rsa==NULL)
return 0;
free(key);
int rsasize=RSA_size(rsa);
int result=-1;
QByteArray encdata=QByteArray::fromHex(QByteArray::fromStdString( data.toStdString()));
QByteArray signByteArray;
int data_len=encdata.length();
int b=0;
int s=data_len/(rsasize);//片数
if(data_len%(rsasize))
s++;
for(int i=0;i<s;i++)
{
QByteArray subdata={0};
for(int j=0;j<rsasize;j++)
{
if(i*rsasize+j>data_len)
break;
subdata[j]=encdata[j+i*rsasize];
}
unsigned char *smldata=(unsigned char*)subdata.data();//(unsigned char*)strdup(subdata.constData());//数据分片
unsigned char smlencrypted[1024]={0};//片段加密数据
b +=RSA_public_decrypt(rsasize,smldata,smlencrypted,rsa,padding);
if(b>0)
{
QByteArray decdata((char*)smlencrypted);
signByteArray.append(decdata);
}
}
QByteArray b1= QByteArray::fromBase64(signByteArray,QByteArray::Base64Encoding);
std::string str=b1.toStdString();
decrypted.append(QString::fromStdString( str));
result=b;
return result;
}
请自己提取头文件。
前面那段原始的加密解密方法未提供数据分片，所以只能加密长度小于245的字符数组