参考资料
https://blog.csdn.net/enjoyinwind/article/details/23530303
https://blog.csdn.net/stormbjm/article/details/46898757
摘自:https://blog.csdn.net/u011983700/article/details/108240200
最近项目中需要用到RSA加密,网上这方面的资料很多,研究了一番,发现直接用openssl的rsa接口非常方便,可以直接通过别人提供的公钥私钥进行加密解密,也可以通过openssl生成密钥对将公钥提供给别人使用。
具体的RSA加密原理就不在这里赘述,直接上代码,代码参考上面两个链接。
其中的重点记录一下哈:
问题1,openssl提供了bio接口以支持各种形式的秘钥读取。在使用bio接口从内存中读取pem格式的公钥时,总是读取公钥失败,经不断查找资料,发现在我们得到base64编码的RSA公钥后,从内存中读取这个公钥时要注意以下几点:(1)公钥字符串开头要加上“-----BEGIN PUBLIC KEY-----\n”,结尾加上“\n-----END PUBLIC KEY-----\n”。否则会出现error:0906D06C:PEM routines:PEM_read_bio:no start line(2)公钥字符串每隔64个字符要加一个换行,否则会报秘钥格式错误。
问题2,PEM_read_RSA_PUBKEY()函数和PEM_read_RSAPublicKEY()的疑惑。为什么读取私钥文件用的PEM_read_RSAPrivateKey(),针对上述openssl命令生成的公钥文件,在读取其内容时用对称的PEM_read_RSAPublicKEY()接口却会报错,必须要用PEM_read_RSA_PUBKEY()才可以。 原因是生成公钥时要把-pubout参数改成-RSAPublicKey_out
目前支持两种模式获取公钥和私钥。第一种方式比较常用,直接通过文件获取公私钥。第二种方式通过内存获取,这种方式比较灵活,可以将密钥保存在数据库,文件,甚至直接写在代码里,只要使用的时候将其转成对应格式的字符串即可。
另外,由于通过rsa加密以后的二进制密文有时候不太方便传输,所以一般会将其通过base64进行编码然后再进行传输。
在进行代码开发前,首先需要安装openssl库,ubuntu下直接执行一下命令即可。
sudo apt-get install libssl-dev
// rsa.h #ifndef _RSA_H #define _RSA_H #define PRIVATEKEY "key.pem" #define PUBLICKEY "key_pub.pem" int rsa_pub_encrypt(char *str,char *path_key,char** outstr); int rsa_prv_decrypt(char *str,char *path_key,int inlen,char** outstr); #endif
// rsa.c #include<stdio.h> #include<stdlib.h> #include<string.h> #include<openssl/rsa.h> #include<openssl/pem.h> #include<openssl/err.h> #include "rsa.h" #define RSAPUBKEY #define KEYFORMFILE 1 #define KEYFORMMEM 2 #define KEYFORM KEYFORMMEM 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; } 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"; 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; } 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"; 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; }
/*base64.h*/ #ifndef _BASE64_H #define _BASE64_H #include <stdlib.h> #include <string.h> unsigned char *base64_encode(unsigned char *str,int strlen); unsigned char *base64_decode(unsigned char *code,int *codelen); #endif
/*base64.c*/ #include "base64.h" 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<len-2;j+=3,i+=4) { res[i]=base64_table[str[j]>>2]; //取出第一个字符的前6位并找出对应的结果字符 res[i+1]=base64_table[(str[j]&0x3)<<4 | (str[j+1]>>4)]; //将第一个字符的后位与第二个字符的前4位进行组合并找到对应的结果字符 res[i+2]=base64_table[(str[j+1]&0xf)<<2 | (str[j+2]>>6)]; //将第二个字符的后4位与第三个字符的前2位组合并找出对应的结果字符 res[i+3]=base64_table[str[j+2]&0x3f]; //取出第三个字符的后6位并找出结果字符 } switch(str_len % 3) { 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 < len-2;j+=3,i+=4) { res[j]=((unsigned char)table[code[i]])<<2 | (((unsigned char)table[code[i+1]])>>4); //取出第一个字符对应base64表的十进制数的前6位与第二个字符对应base64表的十进制数的后2位进行组合 res[j+1]=(((unsigned char)table[code[i+1]])<<4) | (((unsigned char)table[code[i+2]])>>2); //取出第二个字符对应base64表的十进制数的后4位与第三个字符对应bas464表的十进制数的后4位进行组合 res[j+2]=(((unsigned char)table[code[i+2]])<<6) | ((unsigned char)table[code[i+3]]); //取出第三个字符对应base64表的十进制数的后2位与第4个字符进行组合 } return res; }
// main.c #include<stdio.h> #include<stdlib.h> #include<string.h> #include "base64.h" #include "rsa.h" //#include "aes.h" void ras_test() { char *ptr_en=NULL,*ptr_de=NULL; char *ptr_enbase=NULL,*ptr_debase=NULL; int len; len=rsa_pub_encrypt("abcd1234",PUBLICKEY,&ptr_en); printf("pubkey encrypt=%d:\n",len); ptr_enbase=base64_encode(ptr_en,len); printf("base64_encode len=%d\n",strlen(ptr_enbase)); printf("%s\n",ptr_enbase); int decode_len; ptr_debase=base64_decode("JqdnYAhiZbXNV+h7t3jSj6DcYRwQevRjyz9qg4H7m" "JizgXnUAZ0saWIwrVf+5p+TTTlLzadfSVgM4NtMsqO1kRD/M15u3j/" "009KoKXPa3PZQI3o+r8tkaVloG+LMGt4IndI2jZdZ5gFv8gFQUdkoZ" "jiuXa3NWnX99909dN/l0c8LTyNVF+mKt8EP8nEo6ICq/9sMl0qI8v5" "DiXHRurtJVewH/2+iofAACidXlvihvQsWgt+KDntCwl2+lo+F+Fmcx" "dlntnsPZVibgIYS+Mjoged4782Agp6srMyNsCmarE+mSeyhA3ywK0T" "srUEQoKm3qJVD6XPXVbAO5B6MCVFd0Q==",&decode_len); printf("decode_len=%d\n",decode_len); rsa_prv_decrypt(ptr_debase,PRIVATEKEY,len,&ptr_de); printf("prvkey decrypt:%s\n",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); } } int main(int argc,char** argv) { ras_test(); return 0; }
标签:openssl,base64,解密,len,rsa,char,str,NULL From: https://www.cnblogs.com/LiuYanYGZ/p/17925421.html