我的github：codetoys，所有代码都将会位于ctfc库中。已经放入库中我会指出在库中的位置。
这些代码大部分以Linux为目标但部分代码是纯C++的，可以在任何平台上使用。
这是一个基于OpenSSL的AES-CBC加密的例子，其中CBC是自行实现的，原因是OpenSSL的CBC始终有问题，可能是我还没做对吧。这个例程的目的是对配置数据加密，不用于对外交换，所以CBC有没写对我也不能担保------反正这个程序自己加密的自己解密是没问题的。
目录
[1 介绍](#1 介绍)
[2 代码概要](#2 代码概要)
[3 主要代码](#3 主要代码)
[4 辅助代码](#4 辅助代码)
[5 openSSL的AES用法](#5 openSSL的AES用法)
[5.1 设置KEY](#5.1 设置KEY)
[5.2 加密解密AES_encrypt/AES_decrypt](#5.2 加密解密AES_encrypt/AES_decrypt)
1 介绍
这个例程是基于CentOS7/8的，64位，OpenSSL大概是1.1，我也在windows上做了测试，代码可能需要修改，CBC的问题同样存在（所以我就放弃解决了，自己写了一个）。
使用OpenSSL需要头文件位置和库，如果头文件安装到标准位置则不需要-I参数，库是 -lssl -lcrypt
2 代码概要
cpp
//需要的OpenSSL的两个头文件
#include <openssl/aes.h>
#include <openssl/rand.h>
class CMyOpenSSL
{
private:
//用来输出十六进制数据
static void show_buf(char const* title, unsigned char const* buf, int len)
{
。。。。。。
}
//需要一个从用户密码生成密钥的函数
//这个函数我没写，有标准算法从密码生成密钥，类似于对密码进行哈希
public:
//这就是一般所说的"盐"
class IV
{
private:
unsigned char iv[AES_BLOCK_SIZE * 5];//其实不需要*5，但我原来就是这么写的，为了调试吧
public:
//执行异或
static void XOR(unsigned char const * iv,unsigned char* data)
{
。。。。。。
}
//用随机数设置
void Create()
{
。。。。。。
}
。。。。。。
};
//由于网上的例子也一样无法解密，所以自行实现CBC
static void my_AES_cbc_encrypt(const unsigned char* in, unsigned char* out, size_t length, const AES_KEY* key, unsigned char* ivec, const int enc)
{
。。。。。。
}
//AES加密
static int aes_encrypt(unsigned char const* userpasswd, int userpasswd_len, vector<unsigned char> const& in_plain, vector<unsigned char>& out_ciphertext, IV& iv)
{
。。。。。。
}
//AES解密
static int aes_decrypt(unsigned char const* userpasswd, int userpasswd_len, vector<unsigned char> const& in_ciphertext, vector<unsigned char>& out_plain, IV& iv)
{
。。。。。。
}
//保护数据，用密码加密并做格式转换
static bool protect_encode(CBuffer const& passwd, CBuffer const& input, CBuffer& output)
{
。。。。。。
}
//保护数据，用密码加密并做格式转换
static bool protect_decode(CBuffer const& passwd, CBuffer const& input, CBuffer& output)
{
。。。。。。
}
//下面两个就是网上别人写的程序，一样得不到正确结果
// a simple hex-print routine. could be modified to print 16 bytes-per-line
static void hex_print(const void* pv, size_t len)
{
。。。。。。
}
// main entrypoint
static int a()
{
。。。。。。
}
//测试代码
static bool aes_test()
{
。。。。。。
}
};主要函数如下：
my_AES_cbc_encrypt 我自己写的AES-CBC加密和解密，调用了openSSL的AES_encrypt和AES_decrypt，想学习AES怎么用看看这个函数就可以了
aes_encrypt AES加密，调用了openSSL的AES_set_encrypt_key和我自己写的my_AES_cbc_encrypt，为了方便把明文长度作为第一个数据块
aes_decrypt AES解密，调用了openSSL的AES_set_decrypt_key和我自己写的my_AES_cbc_encrypt
protect_encode和protect_decode是我自己写的加密配置数据的方法，完全是自定义的
a 是网上找来的测试代码，证明AES-CBC确实有问题，不是我一个人的问题
3 主要代码
下面是主要代码，上面有一些注释是我临时加的，不在完整代码里面，还有一些辅助类后面列出。
cpp
#include <openssl/aes.h>
#include <openssl/rand.h>
class CMyOpenSSL
{
private:
static unsigned char const ver;
static void show_buf(char const* title, unsigned char const* buf, int len)
{
cout << title << " ";
for (int i = 0; i < len; ++i)
{
cout << hex << setw(2) << setfill('0') << (unsigned int)buf[i] << " ";
}
cout << endl;
}
//需要一个从用户密码生成密钥的函数
public:
class IV
{
private:
unsigned char iv[AES_BLOCK_SIZE * 5];
public:
IV()
{
memset(iv, 0, AES_BLOCK_SIZE * 5);
}
//执行异或
static void XOR(unsigned char const * iv,unsigned char* data)
{
//show_buf("IV ", iv, AES_BLOCK_SIZE);
//show_buf("DATA", data, AES_BLOCK_SIZE);
for (int i = 0; i < AES_BLOCK_SIZE; ++i)
{
data[i] ^= iv[i];
}
//show_buf("DATA", data, AES_BLOCK_SIZE);
}
int size()const
{
return AES_BLOCK_SIZE;
}
//用随机数设置
void Create()
{
time_t t = time(NULL);
srand(t);
for (int i = 0; i < AES_BLOCK_SIZE; i += sizeof(int))
{
int a = rand();
memcpy(iv + i, &a, sizeof(int));
}
}
void Set(unsigned char const* a)
{
memcpy(iv, a, AES_BLOCK_SIZE);
}
//注意，会修改内容
unsigned char* Get()
{
//show_buf("", iv, AES_BLOCK_SIZE * 2);
return iv;
}
};
//由于网上的例子也一样无法解密，所以自行实现CBC
static void my_AES_cbc_encrypt(const unsigned char* in, unsigned char* out, size_t length, const AES_KEY* key, unsigned char* ivec, const int enc)
{
for (int i = 0; i < length; i += AES_BLOCK_SIZE)
{
if (AES_ENCRYPT == enc)
{
unsigned char tmpin[AES_BLOCK_SIZE];
memcpy(tmpin, in + i, AES_BLOCK_SIZE);
IV::XOR(ivec, tmpin);
AES_encrypt(tmpin, out + i, key);
memcpy(ivec, out + i, AES_BLOCK_SIZE);
}
else
{
unsigned char tmpiv[AES_BLOCK_SIZE];
memcpy(tmpiv, in + i, AES_BLOCK_SIZE);
AES_decrypt(in + i, out + i, key);
IV::XOR(ivec, out + i);
memcpy(ivec, tmpiv, AES_BLOCK_SIZE);
}
}
}
static int aes_encrypt(unsigned char const* userpasswd, int userpasswd_len, vector<unsigned char> const& in_plain, vector<unsigned char>& out_ciphertext, IV& iv)
{
out_ciphertext.clear();
unsigned char userkey[32];//必须是16/24/32
memset((void*)userkey, '\0', 32);
memcpy(userkey, userpasswd, (userpasswd_len > 32 ? 32 : userpasswd_len));
/*设置加密key及密钥长度*/
AES_KEY key;
if (AES_set_encrypt_key(userkey, 32 * 8, &key) < 0)
{
return __LINE__;
}
int len = 0;
/*循环加密，每次只能加密AES_BLOCK_SIZE长度的数据*/
out_ciphertext.reserve(in_plain.size() + AES_BLOCK_SIZE);
while (len < in_plain.size())
{
if (0 == len)
{//第一个块是明文长度
out_ciphertext.resize(out_ciphertext.size() + AES_BLOCK_SIZE);
unsigned char tmp[AES_BLOCK_SIZE];
memset((void*)tmp, '\0', AES_BLOCK_SIZE);
long tmp_len = in_plain.size();
memcpy(tmp, &tmp_len, sizeof(long));
//show_buf("明文长度加密前 ", tmp, AES_BLOCK_SIZE);
my_AES_cbc_encrypt(tmp, &out_ciphertext[out_ciphertext.size() - AES_BLOCK_SIZE], AES_BLOCK_SIZE, &key, iv.Get(), AES_ENCRYPT);
//show_buf("明文长度加密后", &out_ciphertext[out_ciphertext.size() - AES_BLOCK_SIZE], AES_BLOCK_SIZE);
}
out_ciphertext.resize(out_ciphertext.size() + AES_BLOCK_SIZE);
if (in_plain.size() - len < AES_BLOCK_SIZE)
{
unsigned char tmp[AES_BLOCK_SIZE];
memset((void*)tmp, '\0', AES_BLOCK_SIZE);
memcpy(tmp, &in_plain[len], in_plain.size() - len);
my_AES_cbc_encrypt(tmp, &out_ciphertext[out_ciphertext.size() - AES_BLOCK_SIZE], AES_BLOCK_SIZE, &key, iv.Get(), AES_ENCRYPT);
}
else
{
my_AES_cbc_encrypt(&in_plain[len], &out_ciphertext[out_ciphertext.size() - AES_BLOCK_SIZE], AES_BLOCK_SIZE, &key, iv.Get(), AES_ENCRYPT);
}
len += AES_BLOCK_SIZE;
}
return 0;
}
static int aes_decrypt(unsigned char const* userpasswd, int userpasswd_len, vector<unsigned char> const& in_ciphertext, vector<unsigned char>& out_plain, IV& iv)
{
out_plain.clear();
unsigned char userkey[32];//必须是16/24/32
memset((void*)userkey, '\0', 32);
memcpy(userkey, userpasswd, (userpasswd_len > 32 ? 32 : userpasswd_len));
/*设置解密key及密钥长度*/
AES_KEY key;
if (AES_set_decrypt_key(userkey, 32 * 8, &key) < 0)
{
return __LINE__;
}
int len = 0;
/*循环解密*/
out_plain.reserve(in_ciphertext.size());
long out_len = 0;//原始长度，放在第一个加密块
while (len < in_ciphertext.size())
{
if (0 == len)
{//第一个块是明文长度
unsigned char tmp[AES_BLOCK_SIZE];
//show_buf("明文长度解密前", &in_ciphertext[len], AES_BLOCK_SIZE);
my_AES_cbc_encrypt(&in_ciphertext[len], tmp, AES_BLOCK_SIZE, &key, iv.Get(), AES_DECRYPT);
//show_buf("明文长度解密后", tmp, AES_BLOCK_SIZE);
memcpy(&out_len, tmp, sizeof(long));
//thelog << "明文长度应该是 " << out_len << endi;
len += AES_BLOCK_SIZE;
}
out_plain.resize(out_plain.size() + AES_BLOCK_SIZE);
my_AES_cbc_encrypt(&in_ciphertext[len], &out_plain[out_plain.size() - AES_BLOCK_SIZE], AES_BLOCK_SIZE, &key, iv.Get(), AES_DECRYPT);
len += AES_BLOCK_SIZE;
}
//恢复原始长度
if (out_plain.size() > out_len)out_plain.resize(out_len);
return 0;
}
//保护数据，用密码加密并做格式转换
static bool protect_encode(CBuffer const& passwd, CBuffer const& input, CBuffer& output)
{
output.setSize(0);
IV iv;
iv.Create();
CBuffer tmp;
tmp.AddData(&ver, 1);//第一个字节是版本
tmp.AddData(iv.Get(), iv.size());//然后是IV，必须在加密之前保存，加密之后会改变
//加密
vector<unsigned char> in_plain;
in_plain.resize(input.size());
memcpy(&in_plain[0], input.data(), input.size());
vector<unsigned char> out_ciphertext;
aes_encrypt(passwd.data(), passwd.size(), in_plain, out_ciphertext, iv);
thelog << out_ciphertext.size() << endi;
//添加加密后数据
tmp.AddData(&out_ciphertext[0], out_ciphertext.size());
thelog << tmp.size() << endi;
output.reserve(tmp.size() * 4 / 3 + 4 + 1);//三字节转为4字节，编码函数在最后还会加上一个字符串结束符
thelog << output.capacity() << " " << output.size() << endi;
int n = CBase64::Base64Enc(output.lockBuffer(), tmp.data(), tmp.size());
output.releaseBuffer();
if (n > output.capacity())thelog << "长度不足" << ende;
output.setSize(n);
thelog << output.size() << " [" << output.data() << "]" << endi;
return true;
}
//保护数据，用密码加密并做格式转换
static bool protect_decode(CBuffer const& passwd, CBuffer const& input, CBuffer& output)
{
output.setSize(0);
CBuffer tmp;
//这里导致了奇怪的内存错误，实际并不需要这么长
tmp.reserve(input.size() + 100);//实际需要的是4转3,解码函数最后会加上一个字符串结束符
//thelog << input.size() << " " << tmp.capacity() << " " << tmp.size() << endi;
int n = CBase64::Base64Dec(tmp.lockBuffer(), input.data(), input.size());
tmp.releaseBuffer();
if (n<0 || n > tmp.capacity())thelog << "长度不足" << ende;
tmp.setSize(n);
if (tmp.data()[0] != ver)
{
thelog << "加密版本错误" << ende;
return false;
}
else
{
//thelog << "加密版本 " << (int)tmp.data()[0]<<" " << (int)ver << ende;
}
IV iv;
iv.Set(tmp.data() + 1);
vector<unsigned char> in_plain;
in_plain.resize(tmp.size() - 1 - iv.size());
memcpy(&in_plain[0], tmp.data() + 1 + iv.size(), tmp.size() - 1 - iv.size());
//thelog << tmp.size() << " " << in_plain.size() << endi;
vector<unsigned char> out_ciphertext;
aes_decrypt(passwd.data(), passwd.size(), in_plain, out_ciphertext, iv);
output.AddData(&out_ciphertext[0], out_ciphertext.size());
return true;
}
// a simple hex-print routine. could be modified to print 16 bytes-per-line
static void hex_print(const void* pv, size_t len)
{
const unsigned char* p = (const unsigned char*)pv;
if (NULL == pv) {
printf("NULL");
}
else {
size_t i = 0;
for (; i < len; ++i) {
printf("%02X ", *p++);
}
}
printf("\n");
}
// main entrypoint
static int a()
{
int const keylength = 128;
/* generate a key with a given length */
unsigned char aes_key[keylength / 8];
memset(aes_key, 0, keylength / 8);
if (!RAND_bytes(aes_key, keylength / 8)) {
exit(-1);
}
size_t const inputslength = 16;
/* generate input with a given length */
unsigned char aes_input[inputslength];
memset(aes_input, 1, inputslength);
/* init vector */
unsigned char iv_enc[AES_BLOCK_SIZE], iv_dec[AES_BLOCK_SIZE];
RAND_bytes(iv_enc, AES_BLOCK_SIZE);
memcpy(iv_dec, iv_enc, AES_BLOCK_SIZE);
// buffers for encryption and decryption
const size_t encslength = ((inputslength + AES_BLOCK_SIZE) / AES_BLOCK_SIZE) * AES_BLOCK_SIZE;
unsigned char enc_out[encslength];
unsigned char dec_out[inputslength];
memset(enc_out, 0, sizeof(enc_out));
memset(dec_out, 0, sizeof(dec_out));
// so i can do with this aes-cbc-128 aes-cbc-192 aes-cbc-256
AES_KEY enc_key, dec_key;
AES_set_encrypt_key(aes_key, keylength, &enc_key);
AES_cbc_encrypt(aes_input, enc_out, inputslength, &enc_key, iv_enc, AES_ENCRYPT);
AES_set_decrypt_key(aes_key, keylength, &dec_key);
AES_cbc_encrypt(enc_out, dec_out, encslength, &dec_key, iv_dec, AES_DECRYPT);
printf("original:\t");
hex_print(aes_input, sizeof(aes_input));
printf("encrypt:\t");
hex_print(enc_out, sizeof(enc_out));
printf("decrypt:\t");
hex_print(dec_out, sizeof(dec_out));
return 0;
}
static bool aes_test()
{
if (true)
{
unsigned char userkey[32];//必须是16/24/32
memset((void*)userkey, '\0', 32);
memcpy(userkey, "12345", 5);
AES_KEY key;
if (AES_set_encrypt_key(userkey, 16 * 8, &key) < 0)
{
return __LINE__;
}
unsigned char iv[AES_BLOCK_SIZE];
unsigned char data[AES_BLOCK_SIZE];
memset(data, 1, AES_BLOCK_SIZE);
unsigned char data2[AES_BLOCK_SIZE];
memset(data2, 0, AES_BLOCK_SIZE);
unsigned char data3[AES_BLOCK_SIZE * 3];
memset(data3, 0, AES_BLOCK_SIZE * 3);
memset(iv, 0, AES_BLOCK_SIZE);
show_buf("简单输入 ", data, AES_BLOCK_SIZE);
show_buf("iv ", iv, AES_BLOCK_SIZE);
AES_cbc_encrypt(data, data2, AES_BLOCK_SIZE, &key, iv, AES_ENCRYPT);
show_buf("加密后 ", data2, AES_BLOCK_SIZE);
show_buf("iv ", iv, AES_BLOCK_SIZE);
if (AES_set_decrypt_key(userkey, 16 * 8, &key) < 0)
{
return __LINE__;
}
memset(iv, 0, AES_BLOCK_SIZE);
show_buf("解密前 ", data2, AES_BLOCK_SIZE);
show_buf("iv ", iv, AES_BLOCK_SIZE);
AES_cbc_encrypt(data2, data3, AES_BLOCK_SIZE, &key, iv, AES_DECRYPT);
show_buf("简单输出 ", data3, AES_BLOCK_SIZE * 3);
show_buf("iv ", iv, AES_BLOCK_SIZE);
a();
}
if (true)
{
string passwd = "13579";
vector<unsigned char> plaintext;
for (int i = 0; i < 65; ++i)
{
plaintext.push_back(i);
}
vector<unsigned char> out;
IV iv;
iv.Create();
IV iv2;
iv2.Set(iv.Get());
//show_buf("初始IV", iv.Get(), iv.size());
aes_encrypt((unsigned char*)passwd.c_str(), passwd.size(), plaintext, out, iv);
vector<unsigned char> plaintext2;
//show_buf("初始IV", iv2.Get(), iv2.size());
aes_decrypt((unsigned char*)passwd.c_str(), passwd.size(), out, plaintext2, iv2);
thelog << plaintext.size() << " " << out.size() << " " << plaintext2.size() << ENDI;
printf("plantext2: \n");
for (int i = 0; i < plaintext2.size(); i++)
{
printf("%.2x ", plaintext2[i]);
if ((i + 1) % 32 == 0)
{
printf("\n");
}
}
printf("\n");
}
if (true)
{
try
{
char const* plaintext = "1234567890";
CBuffer pass;
CBuffer in;
CBuffer out;
pass.SetData("123");
in.SetData(plaintext);
thelog << in.data() << endi;
protect_encode(pass, in, out);
thelog << out.size() << " [" << out.data() << "]" << endi;
CBuffer out2;
if (!protect_decode(pass, out, out2))thelog << "解码失败" << ende;
thelog << out2.data() << endi;
if (0 == strcmp(plaintext, (char*)out2.data()))
{
thelog << "匹配成功" << endi;
}
else
{
thelog << "匹配失败" << ende;
}
//out2.lockBuffer();
//out2.setSize(10240);
}
catch (...)
{
thelog << "异常发生" << ende;
}
}
return true;
}
};4 辅助代码
thelog可以替换为cout，endi、ende可以替换为endl。
CBuffer就是个包装的缓冲区，代码如下：
cpp
//内部隐含保持一个结束符，不计算在容量和大小之内，确保数据可以被当作字符串使用
class CBuffer
{
private:
string name;
unsigned char* p = NULL;
size_t buffer_size = 0;
size_t data_size = 0;
bool bLockBuffer = false;
void _init()
{
static int i = 0;
char buf[64];
sprintf(buf, "CBuffer%d", i++);
name = buf;
if (p)throw "p不为空指针";
p = new unsigned char[1];
if (!p)throw "内存不足";
p[0] = '\0';
buffer_size = 0;
}
public:
CBuffer()
{
_init();
}
CBuffer(CBuffer const & tmp)
{
_init();
SetData(tmp.data(), tmp.data_size);
}
CBuffer & operator=(CBuffer const & tmp)
{
_init();
SetData(tmp.data(), tmp.data_size);
return *this;
}
~CBuffer()
{
//cout << "~CBuffer " << name <<" "<<(long)p<<" "<< buffer_size<<" "<<data_size << endl;
if (p)delete[]p;
data_size = 0;
buffer_size = 0;
p = NULL;
}
size_t capacity()const { return buffer_size; }
size_t size()const { return data_size; }
unsigned char const * data()const { return p; }
unsigned char* lockBuffer()
{
bLockBuffer = true;
return p;
}
void releaseBuffer() { bLockBuffer = false; }
void setSize(long s)
{
reserve(s);
p[s] = '\0';
data_size = s;
}
bool reserve(size_t n)
{
if (n > buffer_size)
{
if (bLockBuffer)
{
cout << "缓冲区已锁定" << endl;
throw "缓冲区已锁定";
}
//cout << name << " "<< "reserve " << (long)p << " " << buffer_size << " " << data_size << endl;
//cout << name<<"需要扩展 " << buffer_size << " -> " << n << endl;
unsigned char * p2 = new unsigned char[n + 1];
if (p2)
{
if (p)
{
memmove(p2, p, data_size);
delete[]p;
}
buffer_size = n;
p2[data_size] = '\0';
p = p2;
//cout << name<< "扩展成功 " << buffer_size << " -> " << n << endl;
return true;
}
else
{
//cout << name<<"扩展失败 " << buffer_size << " -> " << n << endl;
return false;
}
}
return true;
}
bool AddData(void const * data, long len)
{
if (!reserve(data_size + len))return false;
memmove(p + data_size, data, len);
setSize(data_size + len);
return true;
}
bool SetData(char const * sz)
{
setSize(0);
return AddData((void *)sz, strlen(sz));
}
bool SetData(unsigned char const* sz, long len)
{
return SetData((char const*)sz,len);
}
bool SetData(char const* sz, long len)
{
setSize(0);
return AddData((void *)sz, len);
}
bool Compare(CBuffer const & tmp)const
{
if (data_size != tmp.data_size)return false;
if (data_size > 0)return 0 == memcmp(tmp.data(), data(), data_size);
else return true;
}
};CBase64是Base64编码，代码如下：
cpp
class CBase64
{
public:
static int Base64Enc(unsigned char *buf, unsigned char const *text,int size)
{
static unsigned char const * base64_encoding = (unsigned char const*)"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int buflen = 0;
while(size>0)
{
*buf++ = base64_encoding[ (text[0] >> 2 ) & 0x3f];
if(size>2)
{
*buf++ = base64_encoding[((text[0] & 3) << 4) | (text[1] >> 4)];
*buf++ = base64_encoding[((text[1] & 0xF) << 2) | (text[2] >> 6)];
*buf++ = base64_encoding[text[2] & 0x3F];
}
else
{
switch(size)
{
case 1:
*buf++ = base64_encoding[(text[0] & 3L) << 4L ];
*buf++ = '=';
*buf++ = '=';
break;
case 2:
*buf++ = base64_encoding[((text[0] & 3) << 4) | (text[1] >> 4)];
*buf++ = base64_encoding[((text[1] & 0x0F) << 2) | (text[2] >> 6)];
*buf++ = '=';
break;
}
}
text +=3;
size -=3;
buflen +=4;
}
*buf = 0;
return buflen;
}
//base64解码的实现
static unsigned char GetBase64Value(unsigned char ch)
{
if ((ch >= 'A') && (ch <= 'Z'))
return ch - 'A';
if ((ch >= 'a') && (ch <= 'z'))
return ch - 'a' + 26;
if ((ch >= '0') && (ch <= '9'))
return ch - '0' + 52;
switch (ch)
{
case '+':
return 62;
case '/':
return 63;
case '=': /* base64 padding */
return 0;
default:
return 0;
}
}
//进行base64解码输入应该是4的倍数(根据mime标准)
//如果不是4倍数返回错误
//注意 如果是最后一个字符 那么长度不准备 可能会多1
//返回buf长度
static int Base64Dec(unsigned char *buf, unsigned char const *text,int size)
{
if(size%4)
return -1;
unsigned char chunk[4];
int parsenum=0;
while(size>0)
{
chunk[0] = GetBase64Value(text[0]);
chunk[1] = GetBase64Value(text[1]);
chunk[2] = GetBase64Value(text[2]);
chunk[3] = GetBase64Value(text[3]);
*buf++ = (chunk[0] << 2) | (chunk[1] >> 4);
*buf++ = (chunk[1] << 4) | (chunk[2] >> 2);
*buf++ = (chunk[2] << 6) | (chunk[3]);
text+=4;
size-=4;
parsenum+=3;
}
buf[parsenum]='\0';
return parsenum;
}
};5 openSSL的AES用法
5.1 设置KEY
加密解密的密钥存储为AES_KEY，需要通过AES_set_encrypt_key或AES_set_decrypt_key来设置：
cpp
static int aes_encrypt(unsigned char const* userpasswd, int userpasswd_len, vector<unsigned char> const& in_plain, vector<unsigned char>& out_ciphertext, IV& iv)
{
out_ciphertext.clear();
unsigned char userkey[32];//必须是16/24/32
memset((void*)userkey, '\0', 32);
memcpy(userkey, userpasswd, (userpasswd_len > 32 ? 32 : userpasswd_len));
/*设置加密key及密钥长度*/
AES_KEY key;
if (AES_set_encrypt_key(userkey, 32 * 8, &key) < 0)
{
return __LINE__;
}
。。。。。。注意加密和解密的函数是不一样的。
5.2 加密解密AES_encrypt/AES_decrypt
这两个函数非常简单，参数只有输入、输出、KEY，简单明了。
（这里是文档结束）