C++ 使用OpenSSL进行Base64编码和解码

我一直在尝试找出用于base64解码和编码的openssl文档。我在下面找到了一些代码片段

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字符*base64（常量无符号字符*input，整数长度）
{
BIO*bmem，*b64；
BUF_MEM*bptr；
b64=BIO_new（BIO_f_base64（））；
bmem=BIO_new（BIO_s_mem（））；
b64=生物推送（b64，bmem）；
BIO_写入（b64，输入，长度）；
BIO_冲洗（b64）；
生物获取记忆ptr（b64和bptr）；
char*buff=（char*）malloc（bptr->length）；
memcpy（buff，bptr->data，bptr->length-1）；
buff[bptr->length-1]=0；
生物自由（b64）；
返回buff；
}
字符*解码64（无符号字符*输入，整数长度）
{
BIO*b64，*bmem；
char*buffer=（char*）malloc（长度）；
memset（缓冲区，0，长度）；
b64=BIO_new（BIO_f_base64（））；
bmem=BIO_new_mem_buf（输入，长度）；
bmem=生物推送（b64，bmem）；
BIO_读取（bmem、缓冲区、长度）；
生物自由（bmem）；
返回缓冲区；
}

这似乎只适用于单行字符串，比如“Start”，当我引入带有换行符和空格等的复杂字符串时，它就失败了

---

它甚至不必是openssl，一个简单的类或函数集做同样的事情就可以了，解决方案有一个非常复杂的构建过程，我正试图避免进入其中并进行多次更改。我选择openssl的唯一原因是，解决方案已经使用库进行了编译。

Base64非常简单；通过快速的谷歌搜索，您应该不会遇到任何数量的实现问题。例如，InternetSoftwareConsortium提供了一个C语言的参考实现，详细的注释解释了该过程

---

openssl实现中的“BIO”功能非常复杂，如果您只进行解码/编码，那么它就不太有用了。

Base64非常简单；通过快速的谷歌搜索，您应该不会遇到任何数量的实现问题。例如，InternetSoftwareConsortium提供了一个C语言的参考实现，详细的注释解释了该过程

---

openssl实现将很多复杂性与“BIO”的东西结合起来，如果您只做解码/编码，那么这些东西（IMHO）就不是很有用。

就我个人而言，我发现openssl API使用起来非常痛苦，除非避免它的成本非常高，否则我会避免使用它。我发现它已经成为加密世界的标准API，这让我感到非常不安

我觉得无聊，我给你写了一个C++。这一个甚至应该处理可能导致安全问题的边缘情况，例如，编码字符串会导致整数溢出，因为它太大

我已经对它做了一些单元测试，所以它应该可以工作

#include <string>
#include <cassert>
#include <limits>
#include <stdexcept>
#include <cctype>

static const char b64_table[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static const char reverse_table[128] = {
   64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
   64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
   64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
   52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
   64,  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, 64, 64, 64, 64, 64,
   64, 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, 64, 64, 64, 64, 64
};

::std::string base64_encode(const ::std::string &bindata)
{
   using ::std::string;
   using ::std::numeric_limits;

   if (bindata.size() > (numeric_limits<string::size_type>::max() / 4u) * 3u) {
      throw ::std::length_error("Converting too large a string to base64.");
   }

   const ::std::size_t binlen = bindata.size();
   // Use = signs so the end is properly padded.
   string retval((((binlen + 2) / 3) * 4), '=');
   ::std::size_t outpos = 0;
   int bits_collected = 0;
   unsigned int accumulator = 0;
   const string::const_iterator binend = bindata.end();

   for (string::const_iterator i = bindata.begin(); i != binend; ++i) {
      accumulator = (accumulator << 8) | (*i & 0xffu);
      bits_collected += 8;
      while (bits_collected >= 6) {
         bits_collected -= 6;
         retval[outpos++] = b64_table[(accumulator >> bits_collected) & 0x3fu];
      }
   }
   if (bits_collected > 0) { // Any trailing bits that are missing.
      assert(bits_collected < 6);
      accumulator <<= 6 - bits_collected;
      retval[outpos++] = b64_table[accumulator & 0x3fu];
   }
   assert(outpos >= (retval.size() - 2));
   assert(outpos <= retval.size());
   return retval;
}

::std::string base64_decode(const ::std::string &ascdata)
{
   using ::std::string;
   string retval;
   const string::const_iterator last = ascdata.end();
   int bits_collected = 0;
   unsigned int accumulator = 0;

   for (string::const_iterator i = ascdata.begin(); i != last; ++i) {
      const int c = *i;
      if (::std::isspace(c) || c == '=') {
         // Skip whitespace and padding. Be liberal in what you accept.
         continue;
      }
      if ((c > 127) || (c < 0) || (reverse_table[c] > 63)) {
         throw ::std::invalid_argument("This contains characters not legal in a base64 encoded string.");
      }
      accumulator = (accumulator << 6) | reverse_table[c];
      bits_collected += 6;
      if (bits_collected >= 8) {
         bits_collected -= 8;
         retval += static_cast<char>((accumulator >> bits_collected) & 0xffu);
      }
   }
   return retval;
}

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静态常量字符b64_表[65]=“ABCDEFGHIJKLMNOPQRSTUVWXYZABCDFGHIJKLMNOPQRSTUVWXYZ0123456789+/”；
静态常量字符反向_表[128]={
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
64,  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, 64, 64, 64, 64, 64,
64, 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, 64, 64, 64, 64, 64
};
：：std:：string base64_encode（const:：std:：string和bindata）
{
使用：：std：：string；
使用：：std：：数值限制；
如果（bindata.size（）>（数值限制：：max（）/4u）*3u）{
throw:：std:：length_错误（“将太大的字符串转换为base64”）；
}
常量：：std：：size\u t binlen=bindata.size（）；
//使用=标记，以便端部正确填充。
字符串检索（（（binlen+2）/3）*4），“=”；
：：std：：大小输出=0；
收集的整数位=0；
无符号整数累加器=0；
常量字符串：：常量迭代器binend=bindata.end（）；
for（string:：const_迭代器i=bindata.begin（）；i！=binend；++i）{
累加器=（累加器=6）{
收集的比特数_-=6；
retval[outpos++]=b64_表[（累加器>>收集的位）&0x3fu]；
}
}
如果（收集的位>0）{//任何缺少的尾随位。
断言（收集的位小于6）；
累加器（63））{
throw:：std:：无效的_参数（“它包含base64编码字符串中不合法的字符。”）；
}
累加器=（累加器=8）{
收集的比特数_-=8；
retval+=静态（累加器>>收集的位）&0xffu；
}
}
返回返回；
}

就我个人而言，我发现OpenSSL API使用起来非常痛苦，我避免使用它，除非避免它的成本非常高。我发现它已经成为加密世界的标准API，这让我感到非常不安

我觉得无聊，我给你写了一个C++。这一个甚至应该处理可能导致安全问题的边缘情况，例如，编码字符串会导致整数溢出，因为它太大

我已经对它做了一些单元测试，所以它应该可以工作

#include <string>
#include <cassert>
#include <limits>
#include <stdexcept>
#include <cctype>

static const char b64_table[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static const char reverse_table[128] = {
   64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
   64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
   64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
   52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
   64,  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, 64, 64, 64, 64, 64,
   64, 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, 64, 64, 64, 64, 64
};

::std::string base64_encode(const ::std::string &bindata)
{
   using ::std::string;
   using ::std::numeric_limits;

   if (bindata.size() > (numeric_limits<string::size_type>::max() / 4u) * 3u) {
      throw ::std::length_error("Converting too large a string to base64.");
   }

   const ::std::size_t binlen = bindata.size();
   // Use = signs so the end is properly padded.
   string retval((((binlen + 2) / 3) * 4), '=');
   ::std::size_t outpos = 0;
   int bits_collected = 0;
   unsigned int accumulator = 0;
   const string::const_iterator binend = bindata.end();

   for (string::const_iterator i = bindata.begin(); i != binend; ++i) {
      accumulator = (accumulator << 8) | (*i & 0xffu);
      bits_collected += 8;
      while (bits_collected >= 6) {
         bits_collected -= 6;
         retval[outpos++] = b64_table[(accumulator >> bits_collected) & 0x3fu];
      }
   }
   if (bits_collected > 0) { // Any trailing bits that are missing.
      assert(bits_collected < 6);
      accumulator <<= 6 - bits_collected;
      retval[outpos++] = b64_table[accumulator & 0x3fu];
   }
   assert(outpos >= (retval.size() - 2));
   assert(outpos <= retval.size());
   return retval;
}

::std::string base64_decode(const ::std::string &ascdata)
{
   using ::std::string;
   string retval;
   const string::const_iterator last = ascdata.end();
   int bits_collected = 0;
   unsigned int accumulator = 0;

   for (string::const_iterator i = ascdata.begin(); i != last; ++i) {
      const int c = *i;
      if (::std::isspace(c) || c == '=') {
         // Skip whitespace and padding. Be liberal in what you accept.
         continue;
      }
      if ((c > 127) || (c < 0) || (reverse_table[c] > 63)) {
         throw ::std::invalid_argument("This contains characters not legal in a base64 encoded string.");
      }
      accumulator = (accumulator << 6) | reverse_table[c];
      bits_collected += 6;
      if (bits_collected >= 8) {
         bits_collected -= 8;
         retval += static_cast<char>((accumulator >> bits_collected) & 0xffu);
      }
   }
   return retval;
}

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静态常量字符b64_表[65]=“ABCDEFGHIJKLMNOPQRSTUVWXYZABCDFGHIJKLMNOPQRSTUVWXYZ0123456789+/”；
静态常量字符反向_表[128]={
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
64,  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, 64, 64, 64, 64, 64,
64, 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, 64, 64, 64,
unsigned char *encodeb64mem( unsigned char *data, int len, int *lenoutput )
{
// bio is simply a class that wraps BIO* and it free the BIO in the destructor.

BIO *b64 = BIO_new(BIO_f_base64()); // create BIO to perform base64
BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);

BIO *mem = BIO_new(BIO_s_mem()); // create BIO that holds the result

// chain base64 with mem, so writing to b64 will encode base64 and write to mem.
BIO_push(b64, mem);

// write data
bool done = false;
int res = 0;
while(!done)
{
    res = BIO_write(b64, data, len);

    if(res <= 0) // if failed
    {
        if(BIO_should_retry(b64)){
            continue;
        }
        else // encoding failed
        {
            /* Handle Error!!! */
        }
    }
    else // success!
        done = true;
}

BIO_flush(b64);

// get a pointer to mem's data
unsigned char* output;
*lenoutput = BIO_get_mem_data(mem, &output);

// assign data to output
//std::string s(dt, len2);

return output;
}

int encodeb64(unsigned char* input, const char* filenm, int leni)
{
BIO *b64 = BIO_new(BIO_f_base64());
BIO_set_flags(b64,BIO_FLAGS_BASE64_NO_NL);

BIO *file = BIO_new_file(filenm, "w");
BIO *mem = BIO_new(BIO_f_buffer());
BIO_push(b64, mem);
BIO_push(mem, file);

// write data
bool done = false;
int res = 0;
while(!done)
{
    res = BIO_write(b64, input, leni);

    if(res <= 0) // if failed
    {
        if(BIO_should_retry(b64)){
            continue;
        }
        else // encoding failed
        {
            /* Handle Error!!! */
        }
    }
    else // success!
        done = true;
}

BIO_flush(b64);
BIO_pop(b64);
BIO_free_all(b64);

    return 0;
}

int encodeb64FromFile(const char* input, const char* outputfilename)
{
BIO *b64 = BIO_new(BIO_f_base64());
BIO_set_flags(b64,BIO_FLAGS_BASE64_NO_NL);
int leni = 3*64;
unsigned char *data[3*64];
BIO *file = BIO_new_file(outputfilename, "w");
BIO *mem = BIO_new(BIO_f_buffer());
BIO_push(b64, mem);
BIO_push(mem, file);

FILE *fp = fopen(input, "rb");
while ((leni = fread(data, 1, sizeof data, fp)) > 0) {
    // write data
    bool done = false;
    int res = 0;
    while(!done)
    {
        res = BIO_write(b64, data, leni);

        if(res <= 0) // if failed
        {
            if(BIO_should_retry(b64)){
                continue;
            }
            else // encoding failed
            {
                /* Handle Error!!! */
            }
        }
        else // success!
            done = true;
    }

 }

 BIO_flush(b64);
BIO_pop(b64);
BIO_free_all(b64);
fclose(fp);

return 0;
 }

#include <openssl/bio.h>
#include <openssl/evp.h>
#include <cstring>
#include <memory>
#include <string>
#include <vector>

#include <iostream>

namespace {
struct BIOFreeAll { void operator()(BIO* p) { BIO_free_all(p); } };
}

std::string Base64Encode(const std::vector<unsigned char>& binary)
{
    std::unique_ptr<BIO,BIOFreeAll> b64(BIO_new(BIO_f_base64()));
    BIO_set_flags(b64.get(), BIO_FLAGS_BASE64_NO_NL);
    BIO* sink = BIO_new(BIO_s_mem());
    BIO_push(b64.get(), sink);
    BIO_write(b64.get(), binary.data(), binary.size());
    BIO_flush(b64.get());
    const char* encoded;
    const long len = BIO_get_mem_data(sink, &encoded);
    return std::string(encoded, len);
}

// Assumes no newlines or extra characters in encoded string
std::vector<unsigned char> Base64Decode(const char* encoded)
{
    std::unique_ptr<BIO,BIOFreeAll> b64(BIO_new(BIO_f_base64()));
    BIO_set_flags(b64.get(), BIO_FLAGS_BASE64_NO_NL);
    BIO* source = BIO_new_mem_buf(encoded, -1); // read-only source
    BIO_push(b64.get(), source);
    const int maxlen = strlen(encoded) / 4 * 3 + 1;
    std::vector<unsigned char> decoded(maxlen);
    const int len = BIO_read(b64.get(), decoded.data(), maxlen);
    decoded.resize(len);
    return decoded;
}

int main()
{
    const char* msg = "hello";
    const std::vector<unsigned char> binary(msg, msg+strlen(msg));
    const std::string encoded = Base64Encode(binary);
    std::cout << "encoded = " << encoded << std::endl;
    const std::vector<unsigned char> decoded = Base64Decode(encoded.c_str());
    std::cout << "decoded = ";
    for (unsigned char c : decoded) std::cout << c;
    std::cout << std::endl;
    return 0;
}

g++ -lcrypto main.cc

encoded = aGVsbG8=
decoded = hello

#include <iostream>
#include <stdlib.h>
#include <openssl/evp.h>

char *base64(const unsigned char *input, int length) {
  const auto pl = 4*((length+2)/3);
  auto output = reinterpret_cast<char *>(calloc(pl+1, 1)); //+1 for the terminating null that EVP_EncodeBlock adds on
  const auto ol = EVP_EncodeBlock(reinterpret_cast<unsigned char *>(output), input, length);
  if (pl != ol) { std::cerr << "Whoops, encode predicted " << pl << " but we got " << ol << "\n"; }
  return output;
}

unsigned char *decode64(const char *input, int length) {
  const auto pl = 3*length/4;
  auto output = reinterpret_cast<unsigned char *>(calloc(pl+1, 1));
  const auto ol = EVP_DecodeBlock(output, reinterpret_cast<const unsigned char *>(input), length);
  if (pl != ol) { std::cerr << "Whoops, decode predicted " << pl << " but we got " << ol << "\n"; }
  return output;
}

#include <openssl/evp.h>

#include <memory>
#include <stdexcept>
#include <vector>


auto EncodeBase64(const std::string& to_encode) -> std::string {
  /// @sa https://www.openssl.org/docs/manmaster/man3/EVP_EncodeBlock.html

  const auto predicted_len = 4 * ((to_encode.length() + 2) / 3);  // predict output size

  const auto output_buffer{std::make_unique<char[]>(predicted_len + 1)};

  const std::vector<unsigned char> vec_chars{to_encode.begin(), to_encode.end()};  // convert to_encode into uchar container

  const auto output_len = EVP_EncodeBlock(reinterpret_cast<unsigned char*>(output_buffer.get()), vec_chars.data(), static_cast<int>(vec_chars.size()));

  if (predicted_len != static_cast<unsigned long>(output_len)) {
    throw std::runtime_error("EncodeBase64 error");
  }

  return output_buffer.get();
}

auto DecodeBase64(const std::string& to_decode) -> std::string {
  /// @sa https://www.openssl.org/docs/manmaster/man3/EVP_DecodeBlock.html

  const auto predicted_len = 3 * to_decode.length() / 4;  // predict output size

  const auto output_buffer{std::make_unique<char[]>(predicted_len + 1)};

  const std::vector<unsigned char> vec_chars{to_decode.begin(), to_decode.end()};  // convert to_decode into uchar container

  const auto output_len = EVP_DecodeBlock(reinterpret_cast<unsigned char*>(output_buffer.get()), vec_chars.data(), static_cast<int>(vec_chars.size()));

  if (predicted_len != static_cast<unsigned long>(output_len)) {
    throw std::runtime_error("DecodeBase64 error");
  }

  return output_buffer.get();
}

void evp_encode_ctx_set_flags(EVP_ENCODE_CTX *ctx, unsigned int flags);

/* EVP_ENCODE_CTX flags */
/* Don't generate new lines when encoding */
#define EVP_ENCODE_CTX_NO_NEWLINES          1
/* Use the SRP base64 alphabet instead of the standard one */
#define EVP_ENCODE_CTX_USE_SRP_ALPHABET     2

if (EVP_ENCODE_CTX *context = EVP_ENCODE_CTX_new())
{
    EVP_EncodeInit(context);
    evp_encode_ctx_set_flags(context, EVP_ENCODE_CTX_NO_NEWLINES);
    while (hasData())
    {
        uint8_t *data;
        int32_t length = fetchData(&data);
        int32_t size = (((EVP_ENCODE_CTX_num(context) + length)/48) * 65) + 1;
        uint8_t buffer[size];
        EVP_EncodeUpdate(context, buffer, &size, pData, length);
        //process encoded data.
    }
    uint8_t buffer[65];
    int32_t writtenBytes;
    EVP_EncodeFinal(context, buffer, &writtenBytes);
    //Do something with the final remainder of the encoded string.
    EVP_ENCODE_CTX_free(context);
}

#include <openssl/bio.h>
#include <openssl/evp.h>
#include <openssl/buffer.h>
#include <string>

std::string base64_encode(const std::string& input)
{
    const auto base64_memory = BIO_new(BIO_s_mem());
    auto base64 = BIO_new(BIO_f_base64());
    base64 = BIO_push(base64, base64_memory);
    BIO_write(base64, input.c_str(), static_cast<int>(input.length()));
    BIO_flush(base64);
    BUF_MEM* buffer_memory{};
    BIO_get_mem_ptr(base64, &buffer_memory);
    auto base64_encoded = std::string(buffer_memory->data, buffer_memory->length - 1);
    BIO_free_all(base64);
    return base64_encoded;
}