参考
1）http://www.ioncannon.net/programming/34/howto-base64-encode-with-cc-and-openssl/
2）http://www.ioncannon.net/programming/122/howto-base64-decode-with-cc-and-openssl/
3）http://*.com/questions/12109960/openssl-base64-decoding-bio-read-returns-0
4）http://*.com/questions/5288076/doing-base64-encoding-and-decoding-in-openssl-c
main.cpp
#include <openssl/evp.h>
#include <openssl/bio.h>
#include <openssl/buffer.h>
#include <string.h>
#include <string>
#include <iostream>
using namespace std;
char * Base64Encode(const char* input, int length, bool with_new_line);
char * Base64Decode(char* input, int length, bool with_new_line);
int main(int argc, char* argv[])
{
cout << "With new line? y/n ";
string option;
cin >> option;
bool with_new_line = ( ("y" == option || "Y" == option) ? true : false );
string enc_input = "Henry Alfred Kissinger is a German-born American writer, political scientist, diplomat, and businessman. A recipient of the Nobel Peace Prize, he served as National Security Advisor and later concurrently as Secretary of State in the administrations of Presidents Richard Nixon and Gerald Ford.";
cout << endl << "To be encoded:" << endl << "~" << enc_input << "~" << endl << endl;
char * enc_output = Base64Encode(enc_input.c_str(), enc_input.length(), with_new_line);
cout << "Base64 Encoded:" << endl << "~" << enc_output << "~" << endl << endl;
string dec_input = enc_output;
char * dec_output = Base64Decode((char *)dec_input.c_str(), dec_input.length(), with_new_line);
cout << "Base64 Decoded:" << endl << "~" << dec_output << "~" << endl << endl;
free(enc_output);
free(dec_output);
}
char * Base64Encode(const char * input, int length, bool with_new_line)
{
BIO * bmem = NULL;
BIO * b64 = NULL;
BUF_MEM * bptr = NULL;
b64 = BIO_new(BIO_f_base64());
if(!with_new_line) {
BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
}
bmem = BIO_new(BIO_s_mem());
b64 = BIO_push(b64, bmem);
BIO_write(b64, input, length);
BIO_flush(b64);
BIO_get_mem_ptr(b64, &bptr);
char * buff = (char *)malloc(bptr->length + 1);
memcpy(buff, bptr->data, bptr->length);
buff[bptr->length] = 0;
BIO_free_all(b64);
return buff;
}
char * Base64Decode(char * input, int length, bool with_new_line)
{
BIO * b64 = NULL;
BIO * bmem = NULL;
char * buffer = (char *)malloc(length);
memset(buffer, 0, length);
b64 = BIO_new(BIO_f_base64());
if(!with_new_line) {
BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
}
bmem = BIO_new_mem_buf(input, length);
bmem = BIO_push(b64, bmem);
BIO_read(bmem, buffer, length);
BIO_free_all(bmem);
return buffer;
}
Makefile
INC_OPT = -I/usr/include/openssl
LNK_OPT = -g -L/usr/lib64/ -lssl
all:
g++ main.cpp -g -o test $(INC_OPT) $(LNK_OPT)
执行结果1（编码结果每64个字符换行一次）
[root@ampcommons02 base64-test]# ./test执行结果2（编码结果不换行）
With new line? y/n y
To be encoded:
~Henry Alfred Kissinger is a German-born American writer, political scientist, diplomat, and businessman. A recipient of the Nobel Peace Prize, he served as National Security Advisor and later concurrently as Secretary of State in the administrations of Presidents Richard Nixon and Gerald Ford.~
Base64 Encoded:
~SGVucnkgQWxmcmVkIEtpc3NpbmdlciBpcyBhIEdlcm1hbi1ib3JuIEFtZXJpY2Fu
IHdyaXRlciwgcG9saXRpY2FsIHNjaWVudGlzdCwgZGlwbG9tYXQsIGFuZCBidXNp
bmVzc21hbi4gQSByZWNpcGllbnQgb2YgdGhlIE5vYmVsIFBlYWNlIFByaXplLCBo
ZSBzZXJ2ZWQgYXMgTmF0aW9uYWwgU2VjdXJpdHkgQWR2aXNvciBhbmQgbGF0ZXIg
Y29uY3VycmVudGx5IGFzIFNlY3JldGFyeSBvZiBTdGF0ZSBpbiB0aGUgYWRtaW5p
c3RyYXRpb25zIG9mIFByZXNpZGVudHMgUmljaGFyZCBOaXhvbiBhbmQgR2VyYWxk
IEZvcmQu
~
Base64 Decoded:
~Henry Alfred Kissinger is a German-born American writer, political scientist, diplomat, and businessman. A recipient of the Nobel Peace Prize, he served as National Security Advisor and later concurrently as Secretary of State in the administrations of Presidents Richard Nixon and Gerald Ford.~
[root@ampcommons02 base64-test]# ./test注意
With new line? y/n n
To be encoded:
~Henry Alfred Kissinger is a German-born American writer, political scientist, diplomat, and businessman. A recipient of the Nobel Peace Prize, he served as National Security Advisor and later concurrently as Secretary of State in the administrations of Presidents Richard Nixon and Gerald Ford.~
Base64 Encoded:
~SGVucnkgQWxmcmVkIEtpc3NpbmdlciBpcyBhIEdlcm1hbi1ib3JuIEFtZXJpY2FuIHdyaXRlciwgcG9saXRpY2FsIHNjaWVudGlzdCwgZGlwbG9tYXQsIGFuZCBidXNpbmVzc21hbi4gQSByZWNpcGllbnQgb2YgdGhlIE5vYmVsIFBlYWNlIFByaXplLCBoZSBzZXJ2ZWQgYXMgTmF0aW9uYWwgU2VjdXJpdHkgQWR2aXNvciBhbmQgbGF0ZXIgY29uY3VycmVudGx5IGFzIFNlY3JldGFyeSBvZiBTdGF0ZSBpbiB0aGUgYWRtaW5pc3RyYXRpb25zIG9mIFByZXNpZGVudHMgUmljaGFyZCBOaXhvbiBhbmQgR2VyYWxkIEZvcmQu~
Base64 Decoded:
~Henry Alfred Kissinger is a German-born American writer, political scientist, diplomat, and businessman. A recipient of the Nobel Peace Prize, he served as National Security Advisor and later concurrently as Secretary of State in the administrations of Presidents Richard Nixon and Gerald Ford.~
1） 参考1的原文中，Encode示例代码中有一处错误：base64("YOYO!", sizeof("YOYO!")) 应该是 base64("YOYO!", strlen("YOYO!"))
2）参考1的原文中，编码结果中，每64个字符换行一次，整个编码后的字符串的末尾也有换行。这是因为没有做BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL) 操作
3）参考1的原文中，下面红色标记的地方的用法有误！事实上，都要加1！否则，解码还原出来的字符串与编码前的原始字符串相比，丢失两个字符！
char *base64(const unsigned char *input, int length)
{
BIO *bmem, *b64;
BUF_MEM *bptr;
b64 = BIO_new(BIO_f_base64());
bmem = BIO_new(BIO_s_mem());
b64 = BIO_push(b64, bmem);
BIO_write(b64, input, length);
BIO_flush(b64);
BIO_get_mem_ptr(b64, &bptr);
char *buff = (char *)malloc(bptr->length);
memcpy(buff, bptr->data, bptr->length-1);
buff[bptr->length-1] = 0;
BIO_free_all(b64);
return buff;
}
4）上面的实例代码中，Base64Encode() 函数和 Base64Decode() 函数的返回值的buffer 是在Base64Encode() 函数和 Base64Decode() 里面申请的，因此，调用者在使用完这些buffer以后，自己free这些buffer（30、31行）
5）上面的示例代码中，41-43行、67-69行对“编码结果是否有换行”做了区分。这样做是为了方便兼容不带换行的base64编码方式，比如Java的程序用不带换行的base64方式编码的结果，C++也要能解码；或者Java程序只对不带换行的字符串做解码，那么C++代码也要能用不带换行的方式做base64编码。（Java SDK的base64编解码默认是采取不带换行的方式，如果设置了“chunk”属性，可以支持带换行的方式）。注意，这里的换行指的是一个'\n'
6）用openssl 命令行做base64编解码是这样的：
[root@ampcommons02 base64-test]# echo -n "Henry Alfred Kissinger is a German-born American writer, political scientist, diplomat, and businessman." | openssl enc -base64
SGVucnkgQWxmcmVkIEtpc3NpbmdlciBpcyBhIEdlcm1hbi1ib3JuIEFtZXJpY2Fu
IHdyaXRlciwgcG9saXRpY2FsIHNjaWVudGlzdCwgZGlwbG9tYXQsIGFuZCBidXNp
bmVzc21hbi4=
[root@ampcommons02 base64-test]# echo "SGVucnkgQWxmcmVkIEtpc3NpbmdlciBpcyBhIEdlcm1hbi1ib3JuIEFtZXJpY2Fu
> IHdyaXRlciwgcG9saXRpY2FsIHNjaWVudGlzdCwgZGlwbG9tYXQsIGFuZCBidXNp
> bmVzc21hbi4=
> " | openssl enc -base64 -d
Henry Alfred Kissinger is a German-born American writer, political scientist, diplomat, and businessman.[root@ampcommons02 base64-test]#
由上可见，用openssl命令行做base64编码的结果是每64个字符换行一次，整个编码后的字符串的末尾也有换行；同样，用openssl命令行做base64解码的时候，输入的带解码字符串也必须是“每64个字符换行一次，整个编码后的字符串的末尾也有换行”的。