使用openssl中的RSA加密解密

2023-07-20 22:40| 来源: 网络整理| 查看: 265

使用openssl中的RSA加密解密

1. 概念理解

RSA算法是一种非对称密码算法，所谓非对称，就是指该算法需要一对密钥，使用其中一个加密，则需要用另一个才能解密。

2. openssl中的RSA使用

linux控制台下openssl工具的简单使用：

1）安装openssl

sudo apt-get install libssl-dev

2）生成一个密钥：

openssl genrsa -out test.key 1024

这里-out指定生成文件的，即私钥，后面的1024是生成密钥的长度。 3）openssl可以将这个文件中的公钥提取出来：

openssl rsa -in test.key -pubout -out test_pub.key

-in指定输入文件，-out指定提取生成公钥的文件名。现在得到了公钥test_pub.key，私钥test.key。　　 4）在目录中创建一个hello的文本文件，然后利用此前生成的公钥加密文件：

openssl rsautl -encrypt -in hello -inkey test_pub.key -pubin -out hello.en

-in指定要加密的文件，-inkey指定密钥，-pubin表明是用纯公钥文件加密，-out为加密后的文件。　　　 5）解密文件：

openssl rsautl -decrypt -in hello.en -inkey test.key -out hello.de

-in指定被加密的文件，-inkey指定私钥文件，-out为解密后的文件。至此，一次加密解密的过程告终。

3. C语言使用RSA加密解密

使用C语言加密解密时，公钥密钥必须按照64个字节一换行的形式传入，如下面代码所示，在文件中调用也要按照64个字节换行保存。以下代码实现对输入的字符串公钥加密，base64编码，然后base64解码，再用私钥解密。一般通信中，加密解密分别在两端执行。

#include #include #include #include #include #include #include #include #define RSAPUBKEY #define KEYFORMFILE 1 #define KEYFORMMEM 2 #define KEYFORM KEYFORMMEM //内存导入 //#define KEYFORM KEYFORMFILE //文件导入 #define PRIVATEKEY "key.pem" #define PUBLICKEY "key_pub.pem" /* 2020年11月11日 rsa 加密解密 base64 编码解码通过给定私钥公钥完成加密解密公钥私钥放在内存或文件中 */ int rsa_pub_encrypt(char *str,char *path_key,char** outstr); int rsa_prv_decrypt(char *str,char *path_key,int inlen,char** outstr); char* pubkey="-----BEGIN PUBLIC KEY-----\n\ MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAv1Gt1Q3FCo9rgwR1+bsR\ qaInU+2OFnoYdhp2189doeAwP+XH3LLBnxeDRfH1PZKrvEFtKBWaB2112lN4dL/T\ /dSOezszKHPTSg0PaxW4F+ooAY0gTQWGSuSMcY8H4RpkI7sNFFfOYQZYT0albs+e\ RepaHtfQCfM/cFTmpHVDXqdK4uCRNZbhff2+5oEN/j0eW5t4aq+G+Qu1gz9poH5B\ uqea69foG4LRcnwVKCXz+5ZrzE2YWYayvCEgpojXmkLcemvWkJD+K0SUsKoZ/7Wn\ vMBg1mfkSlNTFzpDgKjYESnnUgUobwDtBT9Wdq0RHVVTyZLh4CvZMeS1NcHBqDxp\ PQIDAQAB\ \n-----END PUBLIC KEY-----\n"; char* prikey="-----BEGIN RSA PRIVATE KEY-----\n\ MIIEogIBAAKCAQEAv1Gt1Q3FCo9rgwR1+bsRqaInU+2OFnoYdhp2189doeAwP+XH\ 3LLBnxeDRfH1PZKrvEFtKBWaB2112lN4dL/T/dSOezszKHPTSg0PaxW4F+ooAY0g\ TQWGSuSMcY8H4RpkI7sNFFfOYQZYT0albs+eRepaHtfQCfM/cFTmpHVDXqdK4uCR\ NZbhff2+5oEN/j0eW5t4aq+G+Qu1gz9poH5Buqea69foG4LRcnwVKCXz+5ZrzE2Y\ WYayvCEgpojXmkLcemvWkJD+K0SUsKoZ/7WnvMBg1mfkSlNTFzpDgKjYESnnUgUo\ bwDtBT9Wdq0RHVVTyZLh4CvZMeS1NcHBqDxpPQIDAQABAoIBAGleFLzoLoMYZf/s\ bwUxEBM66SoCBWU/rUUuYhGNdWX30NsANEjKcnSqQHQ/Q++7XbX62qFe9Evu7x9l\ JUw3cgu0Cxy3h/9Zex6nfrxdY9xX69ye2xFQX5vTr73DJnXFUS2UkSmJCnLJSc2v\ fOFAm0yqOyQNe9hfDatSNwyQQKBZ0iiBP4DMfZyW0L0uREDb1Zex4PL5EMt9dlNh\ m6rObetXBXU9Fu1UFSbH2BFzjbsgCJ/kr2ty3hwTv8ygFrNrFJtDfEGdln6vmIiE\ Lbq12UElXtKi2Ko+uulzILFNSSHzi7aJt0y+szBnXkF0XVirvBgIEGCQvL2ynf5O\ Vr96N0kCgYEA7ixwmmjevu4zvcW2nVrXbV+0H0088OKKJMrs92daECL1H/lRCAxI\ MOK6nXEgPy6siMPbErPt3j2bj63HAZVXMfkv4xhn5kCbbhqxS6EsBwoy3hH8Mg9a\ EIbIurdtIZPaElC/nMbD8EoLZpruNhuezQJpsJOm9zIswpj5SYLmEIsCgYEAzaN5\ 2eAyEWPTf8Jd+EwhHfGYRnvdNCnlO1G4mbY5w6UU0grko1uuE7XzCfDYAeRgqUHc\ FDFcj3K/wTofj/KqcUBATy7WolkQOc5TF9P6z8HBPpCaxIHgIT3xMzCLSeSlZkK5\ 5MBEl0kCGYdTOhGFlQkmNfYb9b3Y3AmJ3NVlnlcCgYA2w3ccufJFmoXBI93qboHM\ P04uSFcz2BMFhLdZ56S4wyDzuiLco95Rh0B7hRByFqxLQiV0NnUCPc4wCjgQ8CK9\ dduB7xGsyrwyY+bSSfvSnpC1qRMA+7CsziEHdbedGd7xiSmVxco1zQC0Ffmh7VXl\ M6HTnQ+uFRZfpEbllTiLIwKBgGW2lm7OFfXECrkGyrQl87t75HX4jlFe56OPqF9f\ YvMClGnQOYcTsebN+IjSOAW3kJgnm1PhlobdmztYJIRu4x9hSG3iHQfwRbZR94ex\ sj1Q+OSZYfQQyWun18YaHMtP7P/HwWsELuklk4RNCz2NrSUqgVvvf6TtYnZzwV0Z\ sEnBAoGAF7be2xB6tDoGic/oKahwbR9rviur7zKA+LPapeRwxXElWYCE2ON1NUlF\ +Z+5ajqGjUtQWXDCPqaLO5gSPipPHxX6tYIeolk1C5veZBkeHgG4TLMuIxtpGayw\ 6/P3Pru8xzm8gZZTYqpmnFoXS6gQ2sNtrbyLJNNzH9bUNH7diVU=\ \n-----END RSA PRIVATE KEY-----\n"; static int do_operation(RSA* rsa_ctx,char *instr,char* path_key,int inlen,char** outstr,int type) { if(rsa_ctx == NULL || instr == NULL || path_key == NULL) { perror("input elems error,please check them!"); return -1; } int rsa_len,num; rsa_len=RSA_size(rsa_ctx); *outstr=(unsigned char *)malloc(rsa_len+1); memset(*outstr,0,rsa_len+1); switch(type){ case 1: //pub enc if(inlen == 0){ perror("input str len is zero!"); goto err; } num = RSA_public_encrypt(inlen,(unsigned char *)instr,(unsigned char*)*outstr,rsa_ctx,RSA_PKCS1_PADDING); break; case 2: //prv dec num = RSA_private_decrypt(inlen,(unsigned char *)instr,(unsigned char*)*outstr,rsa_ctx,RSA_PKCS1_PADDING); break; default: break; } if(num == -1) { printf("Got error on enc/dec!\n"); err: free(*outstr); *outstr = NULL; num = -1; } return num; } int rsa_pub_encrypt(char *str,char *path_key,char** outstr) { RSA *p_rsa; BIO *bio = NULL; FILE *file; int flen,rsa_len,num; #if KEYFORM==KEYFORMFILE if((file=fopen(path_key,"r"))==NULL){ perror("open key file error"); return -1; } #else if ((bio = BIO_new_mem_buf(pubkey, -1)) == NULL) //从字符串读取RSA公钥 { perror("BIO_new_mem_buf failed!"); } #endif #ifdef RSAPUBKEY #if KEYFORM==KEYFORMFILE if((p_rsa=PEM_read_RSA_PUBKEY(file,NULL,NULL,NULL))==NULL){ #else if((p_rsa=PEM_read_bio_RSA_PUBKEY(bio,NULL,NULL,NULL))==NULL){ #endif #else if((p_rsa=PEM_read_RSAPublicKey(file,NULL,NULL,NULL))==NULL){ #endif ERR_print_errors_fp(stdout); return -1; } num = do_operation(p_rsa,str,path_key,strlen(str),outstr,1); RSA_free(p_rsa); #if KEYFORM==KEYFORMFILE fclose(file); #else BIO_free_all(bio); #endif return num; } int rsa_prv_decrypt(char *str,char *path_key,int inlen,char** outstr) { RSA *p_rsa; BIO *bio = NULL; FILE *file; int rsa_len,num; #if KEYFORM==KEYFORMFILE if((file=fopen(path_key,"r"))==NULL){ perror("open key file error"); return -1; } #else if ((bio = BIO_new_mem_buf(prikey, -1)) == NULL) //从字符串读取RSA公钥 { perror("BIO_new_mem_buf failed!"); } #endif #if KEYFORM==KEYFORMFILE if((p_rsa=PEM_read_RSAPrivateKey(file,NULL,NULL,NULL))==NULL){ #else if((p_rsa=PEM_read_bio_RSAPrivateKey(bio,NULL,NULL,NULL))==NULL){ #endif ERR_print_errors_fp(stdout); return -1; } num = do_operation(p_rsa,str,path_key,inlen,outstr,2); RSA_free(p_rsa); #if KEYFORM==KEYFORMFILE fclose(file); #else BIO_free_all(bio); #endif return num; } unsigned char *base64_encode(unsigned char *str,int strlen) { long len; long str_len; unsigned char *res; int i,j; //定义base64编码表 unsigned char *base64_table="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; //计算经过base64编码后的字符串长度 str_len=strlen; if(str_len % 3 == 0) len=str_len/3*4; else len=(str_len/3+1)*4; res=malloc(sizeof(unsigned char)*len+1); res[len]='\0'; //以3个8位字符为一组进行编码 for(i=0,j=0;i case 1: res[i-2]='='; res[i-1]='='; break; case 2: res[i-1]='='; break; } return res; } unsigned char *base64_decode(unsigned char *code,int *codelen) { //根据base64表，以字符找到对应的十进制数据 int table[]={0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,62,0,0,0, 63,52,53,54,55,56,57,58, 59,60,61,0,0,0,0,0,0,0,0, 1,2,3,4,5,6,7,8,9,10,11,12, 13,14,15,16,17,18,19,20,21, 22,23,24,25,0,0,0,0,0,0,26, 27,28,29,30,31,32,33,34,35, 36,37,38,39,40,41,42,43,44, 45,46,47,48,49,50,51 }; long len; long str_len; unsigned char *res; int i,j; //计算解码后的字符串长度 len=strlen(code); //判断编码后的字符串后是否有= if(strstr(code,"==")) str_len=len/4*3-2; else if(strstr(code,"=")) str_len=len/4*3-1; else str_len=len/4*3; res=malloc(sizeof(unsigned char)*str_len+1); res[str_len]='\0'; *codelen=str_len; //以4个字符为一位进行解码 for(i=0,j=0;i char *ptr_en=NULL,*ptr_de=NULL; char *ptr_enbase=NULL,*ptr_debase=NULL; int len; int decode_len; char abyInStr[] = "this is my rsa test"; printf("Input String[%d]:\n%s\n",strlen(abyInStr), abyInStr); //加密 len=rsa_pub_encrypt(abyInStr,PUBLICKEY,&ptr_en); printf("rsa_pub_encrypt[%d]\n", len); //64编码 ptr_enbase=base64_encode(ptr_en,len); printf("base64_encode[%d]:\n%s\n",strlen(ptr_enbase), ptr_enbase); //64解码 ptr_debase=base64_decode(ptr_enbase,&decode_len); printf("base64_decode[%d]\n", decode_len); //解密 rsa_prv_decrypt(ptr_debase,PRIVATEKEY,len,&ptr_de); printf("Output String[%d]:\n%s\n",strlen(ptr_de), ptr_de==NULL?"NULL":ptr_de); if(ptr_enbase!=NULL){ free(ptr_enbase); } if(ptr_debase!=NULL){ free(ptr_debase); } if(ptr_en!=NULL){ free(ptr_en); } if(ptr_de!=NULL){ free(ptr_de); } return 0; }

以上代码在linux下编译运行正常，编译时指定链接库-lcrypto

gcc test.c -lcrypto -o test

运行效果如下运行效果图

参考：

https://blog.csdn.net/yyxyong/article/details/77827870 https://blog.csdn.net/u011983700/article/details/108240200

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