2014年3月19日,这篇博文有点老了。但效果仍然是杠杆。
这篇博文解释了如何调用它OpenSSL进行RSA加解密。编程语言使用C。
本博文小节:
①使用OpenSSL生成RSA密钥;
②使用公钥加密,私钥解密;
③使用私钥加密,公钥解密;
④加解密示例代码。
使用OpenSSL生成RSA密钥
用以下命令试生产2048位RSA私钥
openssl genrsa -out private.pem 2048
从私钥中提取公钥:
openssl rsa -in private.pem -outform PEM -pubout -out public.pem
注意生成的证书都是pem格式,这是用的ASCII存的,Base64编码格式。
使用公钥加密,私钥解密
对应的API函数分别为:
int RSA_public_encrypt(int flen, unsigned char *from, unsigned char *to, RSA *rsa, int padding); int RSA_private_decrypt(int flen, unsigned char *from, unsigned char *to, RSA *rsa, int padding);
这里的编程逻辑是先构建一个RSA结构体:
RSA * createRSA(unsigned char * key,int public) { RSA *rsa= NULL; BIO *keybio ; keybio = BIO_new_mem_buf(key, -1); if (keybio==NULL) { printf( "Failed to create key BIO"); return 0; } if(public) { rsa = PEM_read_bio_RSA_PUBKEY(keybio, &rsa,NULL, NULL); } else { rsa = PEM_read_bio_RSAPrivateKey(keybio, &rsa,NULL, NULL); } return rsa; }
这样可以直接创建公钥和私钥
createRSA(“PUBLIC_KEY_BUFFER”,1); createRSA(“PRIVATE_KEY_BUFFER”,0);
如需保存密钥作为文件,可使用以下代码:
RSA * createRSAWithFilename(char * filename,int public) { FILE * fp = fopen(filename,"rb"); if(fp == NULL) { printf("Unable to open file %s \n",filename); return NULL; } RSA *rsa= RSA_new() ; if(public) { rsa = PEM_read_RSA_PUBKEY(fp, &rsa,NULL, NULL); } else { rsa = PEM_read_RSAPrivateKey(fp, &rsa,NULL, NULL); } return rsa; }
公钥加密有以下填充方法:
RSA_PKCS1_PADDING:目前最流行的填充方式。
RSA_PKCS1_OAEP_PADDING:这种加密方法被推荐用于发的应用。
RSA_SSLV23_PADDING:与第一类似,但代表服务器支持更多SSL3.
RSA_NO_PADDING:不要用这个,不好。
以下是使用密钥加密数据:
int padding = RSA_PKCS1_PADDING; int public_encrypt(unsigned char * data,int data_len,unsigned char * key, unsigned char *encrypted) { RSA * rsa = createRSA(key,1); int result = RSA_public_encrypt(data_len,data,encrypted,rsa,padding); return result; }
私钥解密
用以下代码解密:
int private_decrypt(unsigned char * enc_data,int data_len,unsigned char * key, unsigned char *decrypted) { RSA * rsa = createRSA(key,0); int result = RSA_private_decrypt(data_len,enc_data,decrypted,rsa,padding); return result; }
私钥加密,公钥解密
私钥加密实际上是签名的过程。以下对应于私钥加密和公钥解密API。
int RSA_private_encrypt(int flen, unsigned char *from, unsigned char *to, RSA *rsa, int padding); int RSA_public_decrypt(int flen, unsigned char *from, unsigned char *to, RSA *rsa, int padding);
私钥加密只支持两种模式:RSA_PKCS1_PADDIN和RSA_NO_PADDING。
私钥加密:
int private_encrypt(unsigned char * data,int data_len,unsigned char * key, unsigned char *encrypted) { RSA * rsa = createRSA(key,0); int result = RSA_private_encrypt(data_len,data,encrypted,rsa,padding); return result; }
公钥解密:
int public_decrypt(unsigned char * enc_data,int data_len,unsigned char * key, unsigned char *decrypted) { RSA * rsa = createRSA(key,1); int result = RSA_public_decrypt(data_len,enc_data,decrypted,rsa,padding); return result; }
加解密示例代码
以下是一个完整的代码:
RSAEncryptionAndDecryption.pro
QT = core QT -= gui TARGET = RSAEncryptionAndDecryption CONFIG = console CONFIG -= app_bundle QMAKE_CFLAGS = -fpermissive QMAKE_CXXFLAGS = -fpermissive QMAKE_LFLAGS = -fpermissive INCLUDEPATH = /usr/local/ssl/include LIBS = -L /usr/local/ssl/lib/ -lssl -lcrypto TEMPLATE = app SOURCES = main.cpp
main.cpp
#include <QCoreApplication> #include <openssl/pem.h> #include <openssl/ssl.h> #include <openssl/rsa.h> #include <openssl/evp.h> #include <openssl/bio.h> #include <openssl/err.h> int padding = RSA_PKCS1_PADDING; RSA * createRSA(unsigned char * key,int isPublic) { RSA *rsa= NULL; BIO *keybio ; keybio = BIO_new_mem_buf(key, -1); if (keybio==NULL){ printf( "Failed to create key BIO"); return 0; } if(sPublic){
rsa = PEM_read_bio_RSA_PUBKEY(keybio, &rsa,NULL, NULL);
}
else{
rsa = PEM_read_bio_RSAPrivateKey(keybio, &rsa,NULL, NULL);
}
if(rsa == NULL){
printf( "Failed to create RSA");
return NULL;
}
return rsa;
}
int public_encrypt(unsigned char * data,int data_len,unsigned char * key, unsigned char *encrypted)
{
RSA * rsa = createRSA(key,1);
int result = RSA_public_encrypt(data_len,data,encrypted,rsa,padding);
return result;
}
int private_decrypt(unsigned char * enc_data,int data_len,unsigned char * key, unsigned char *decrypted)
{
RSA * rsa = createRSA(key,0);
int result = RSA_private_decrypt(data_len,enc_data,decrypted,rsa,padding);
return result;
}
int private_encrypt(unsigned char * data,int data_len,unsigned char * key, unsigned char *encrypted)
{
RSA * rsa = createRSA(key,0);
int result = RSA_private_encrypt(data_len,data,encrypted,rsa,padding);
return result;
}
int public_decrypt(unsigned char * enc_data,int data_len,unsigned char * key, unsigned char *decrypted)
{
RSA * rsa = createRSA(key,1);
int result = RSA_public_decrypt(data_len,enc_data,decrypted,rsa,padding);
return result;
}
void printLastError(char *msg)
{
rchar * err = malloc(130);;
ERR_load_crypto_strings();
ERR_error_string(ERR_get_error(), err);
printf("%s ERROR: %s\n",msg, err);
free(err);
}
int main(int argc, char *argv[])
{
char plainText[2048/8] = "Hello this is Ravi"; //key length : 2048
char publicKey[]="-----BEGIN PUBLIC KEY-----\n"\
"MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAy8Dbv8prpJ/0kKhlGeJY\n"\
"ozo2t60EG8L0561g13R29LvMR5hyvGZlGJpmn65+A4xHXInJYiPuKzrKUnApeLZ+\n"\
"vw1HocOAZtWK0z3r26uA8kQYOKX9Qt/DbCdvsF9wF8gRK0ptx9M6R13NvBxvVQAp\n"\
"fc9jB9nTzphOgM4JiEYvlV8FLhg9yZovMYd6Wwf3aoXK891VQxTr/kQYoq1Yp+68\n"\
"i6T4nNq7NWC+UNVjQHxNQMQMzU6lWCX8zyg3yH88OAQkUXIXKfQ+NkvYQ1cxaMoV\n"\
"PpY72+eVthKzpMeyHkBn7ciumk5qgLTEJAfWZpe4f4eFZj/Rc8Y8Jj2IS5kVPjUy\n"\
"wQIDAQAB\n"\
"-----END PUBLIC KEY-----\n";
char privateKey[]="-----BEGIN RSA PRIVATE KEY-----\n"\
"MIIEowIBAAKCAQEAy8Dbv8prpJ/0kKhlGeJYozo2t60EG8L0561g13R29LvMR5hy\n"\
"vGZlGJpmn65+A4xHXInJYiPuKzrKUnApeLZ+vw1HocOAZtWK0z3r26uA8kQYOKX9\n"\
"Qt/DbCdvsF9wF8gRK0ptx9M6R13NvBxvVQApfc9jB9nTzphOgM4JiEYvlV8FLhg9\n"\
"yZovMYd6Wwf3aoXK891VQxTr/kQYoq1Yp+68i6T4nNq7NWC+UNVjQHxNQMQMzU6l\n"\
"WCX8zyg3yH88OAQkUXIXKfQ+NkvYQ1cxaMoVPpY72+eVthKzpMeyHkBn7ciumk5q\n"\
"gLTEJAfWZpe4f4eFZj/Rc8Y8Jj2IS5kVPjUywQIDAQABAoIBADhg1u1Mv1hAAlX8\n"\
"omz1Gn2f4AAW2aos2cM5UDCNw1SYmj+9SRIkaxjRsE/C4o9sw1oxrg1/z6kajV0e\n"\
"N/t008FdlVKHXAIYWF93JMoVvIpMmT8jft6AN/y3NMpivgt2inmmEJZYNioFJKZG\n"\
"X+/vKYvsVISZm2fw8NfnKvAQK55yu+GRWBZGOeS9K+LbYvOwcrjKhHz66m4bedKd\n"\
"gVAix6NE5iwmjNXktSQlJMCjbtdNXg/xo1/G4kG2p/MO1HLcKfe1N5FgBiXj3Qjl\n"\
"vgvjJZkh1as2KTgaPOBqZaP03738VnYg23ISyvfT/teArVGtxrmFP7939EvJFKpF\n"\
"1wTxuDkCgYEA7t0DR37zt+dEJy+5vm7zSmN97VenwQJFWMiulkHGa0yU3lLasxxu\n"\
"m0oUtndIjenIvSx6t3Y+agK2F3EPbb0AZ5wZ1p1IXs4vktgeQwSSBdqcM8LZFDvZ\n"\
"uPboQnJoRdIkd62XnP5ekIEIBAfOp8v2wFpSfE7nNH2u4CpAXNSF9HsCgYEA2l8D\n"\
"JrDE5m9Kkn+J4l+AdGfeBL1igPF3DnuPoV67BpgiaAgI4h25UJzXiDKKoa706S0D\n"\
"4XB74zOLX11MaGPMIdhlG+SgeQfNoC5lE4ZWXNyESJH1SVgRGT9nBC2vtL6bxCVV\n"\
"WBkTeC5D6c/QXcai6yw6OYyNNdp0uznKURe1xvMCgYBVYYcEjWqMuAvyferFGV+5\n"\
"nWqr5gM+yJMFM2bEqupD/HHSLoeiMm2O8KIKvwSeRYzNohKTdZ7FwgZYxr8fGMoG\n"\
"PxQ1VK9DxCvZL4tRpVaU5Rmknud9hg9DQG6xIbgIDR+f79sb8QjYWmcFGc1SyWOA\n"\
"SkjlykZ2yt4xnqi3BfiD9QKBgGqLgRYXmXp1QoVIBRaWUi55nzHg1XbkWZqPXvz1\n"\
"I3uMLv1jLjJlHk3euKqTPmC05HoApKwSHeA0/gOBmg404xyAYJTDcCidTg6hlF96\n"\
"ZBja3xApZuxqM62F6dV4FQqzFX0WWhWp5n301N33r0qR6FumMKJzmVJ1TA8tmzEF\n"\
"yINRAoGBAJqioYs8rK6eXzA8ywYLjqTLu/yQSLBn/4ta36K8DyCoLNlNxSuox+A5\n"\
"w6z2vEfRVQDq4Hm4vBzjdi3QfYLNkTiTqLcvgWZ+eX44ogXtdTDO7c+GeMKWz4XX\n"\
"uJSUVL5+CVjKLjZEJ6Qc2WZLl94xSwL71E41H4YciVnSCQxVc4Jw\n"\
"-----END RSA PRIVATE KEY-----\n";
unsigned char encrypted[4098]={};
unsigned char decrypted[4098]={};
int encrypted_length= public_encrypt(plainText,strlen(plainText),publicKey,encrypted);
if(encrypted_length == -1)
{
printLastError("Public Encrypt failed ");
exit(0);
}
printf("Encrypted length =%d\n",encrypted_length);
int decrypted_length = private_decrypt(encrypted,encrypted_length,privateKey, decrypted);
if(decrypted_length == -1)
{
printLastError("Private Decrypt failed ");
exit(0);
}
printf("Decrypted Text =%s\n",decrypted);
printf("Decrypted Length =%d\n",decrypted_length);
encrypted_length= private_encrypt(plainText,strlen(plainText),privateKey,encrypted);
if(encrypted_length == -1)
{
printLastError("Private Encrypt failed");
exit(0);
}
printf("Encrypted length =%d\n",encrypted_length);
decrypted_length = public_decrypt(encrypted,encrypted_length,publicKey, decrypted);
if(decrypted_length == -1)
{
printLastError("Public Decrypt failed");
exit(0);
}
printf("Decrypted Text =%s\n",decrypted);
printf("Decrypted Length =%d\n",decrypted_length);
}
程序运行截图如下:
源码打包下载地址:
Qt/RSAEncryptionAndDecryption at master · fengfanchen/Qt · GitHub