用过的加密方式

用过的加密方式

一、Base64加密

Base64是网络上最常见的用于传输8Bit字节代码的编码方式之一，Base64并不是安全领域的加密算法，其实Base64只能算是一个编码算法，对数据内容进行编码来适合传输。标准Base64编码解码无需额外信息即完全可逆，即使你自己自定义字符集设计一种类Base64的编码方式用于数据加密，在多数场景下也较容易破解。Base64编码本质上是一种将二进制数据转成文本数据的方案。对于非二进制数据，是先将其转换成二进制形式，然后每连续6比特（2的6次方=64）计算其十进制值，根据该值在A--Z,a--z,0--9,+,/ 这64个字符中找到对应的字符，最终得到一个文本字符串。基本规则如下几点：

  1，标准Base64只有64个字符（英文大小写、数字和+、/）以及用作后缀等号；
  2，Base64是把3个字节变成4个可打印字符，所以Base64编码后的字符串一定能被4整除（不算用作后缀的等号）；
  3，等号一定用作后缀，且数目一定是0个、1个或2个。这是因为如果原文长度不能被3整除，Base64要在后面添加凑齐3n位。为了正确还原，添加了几个就加上几个等号。显然添加等号的数目只能是0、1或2；
  4，严格来说Base64不能算是一种加密，只能说是编码转换。
 

使用：

由于二进制的一些字符在网络协议中属于控制字符，不能直接传送，因此需要用Base64编码之后传输，编码之后传输的是一些很普通的ASCII字符。
Base64常用于邮件编码，当邮件中有二进制数据时，就要编码转换。
图片的编码
Url中有二进制数据，这个时候需要Base64编码(Web安全的Base64)
可以进行简单的加密，Base64的编解码规则是透明的，因此用Base64加密时要加盐。

final Base64.Decoder decoder = Decoder();final Base64.Encoder encoder = Encoder();final String text = "字串文字";final byte[] textByte = Bytes("UTF-8");//编码final String encodedText = deToString(textByte);System.out.println(encodedText);//解码System.out.println(new String(decoder.decode(encodedText), "UTF-8"));

二、MD5加密  

飞机：  C++实现代码在下方

1） 压缩性：任意长度的数据，算出的MD5值长度都是固定的。

：MD5使用4个32位的数据，和数据中的每个32位的数据进行计算，最终输出这4个32位数

2）容易计算：从原数据计算出MD5值很容易。

3）抗修改性：对原数据进行任何改动，哪怕只修改1个字节，所得到的MD5值都有很大区别。

4）强抗碰撞：已知原数据和其MD5值，想找到一个具有相同MD5值的数据（即伪造数据）是非常困难的。 

：MD5是个128位的数，那么假设有N个完全不同的文件足够随机足够散列 那么当N大于2^128时才有可能出现重复

使用：

1）一致性验证（密码校验） 2）数字签名 3）安全访问认证

加盐：加盐方式有很多，为防止穷举法破解，可加盐或多次MD5加密

1,string+key（盐值key）然后进行MD5加密

2,用string明文的hashcode作为盐，然后进行MD5加密

3,随机生成一串字符串作为盐，然后进行MD5加密

/*** @file md5.h* @The header file of md5.* @author Jiewei Wei* @mail weijieweijerry@163* @github * @data Oct 19 2014**/#ifndef MD5_H
#define MD5_H/* Parameters of MD5. */
#define s11 7
#define s12 12
#define s13 17
#define s14 22
#define s21 5
#define s22 9
#define s23 14
#define s24 20
#define s31 4
#define s32 11
#define s33 16
#define s34 23
#define s41 6
#define s42 10
#define s43 15
#define s44 21/*** @Basic MD5 functions.** @param there bit32.** @return one bit32.*/
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))/*** @Rotate Left.** @param {num} the raw number.** @param {n} rotate left n.** @return the number after rotated left.*/
#define ROTATELEFT(num, n) (((num) << (n)) | ((num) >> (32-(n))))/*** @Transformations for rounds 1, 2, 3, and 4.*/
#define FF(a, b, c, d, x, s, ac) { (a) += F ((b), (c), (d)) + (x) + ac; (a) = ROTATELEFT ((a), (s)); (a) += (b); 
}
#define GG(a, b, c, d, x, s, ac) { (a) += G ((b), (c), (d)) + (x) + ac; (a) = ROTATELEFT ((a), (s)); (a) += (b); 
}
#define HH(a, b, c, d, x, s, ac) { (a) += H ((b), (c), (d)) + (x) + ac; (a) = ROTATELEFT ((a), (s)); (a) += (b); 
}
#define II(a, b, c, d, x, s, ac) { (a) += I ((b), (c), (d)) + (x) + ac; (a) = ROTATELEFT ((a), (s)); (a) += (b); 
}#include <string>
#include <cstring>using std::string;/* Define of btye.*/
typedef unsigned char byte;
/* Define of byte. */
typedef unsigned int bit32;class MD5 {
public:/* Construct a MD5 object with a string. */MD5(const string& message);/* Generate md5 digest. */const byte* getDigest();/* Convert digest to string value */string toStr();private:/* Initialization the md5 object, processing another message block,* and updating the context.*/void init(const byte* input, size_t len);/* MD5 basic transformation. Transforms state based on block. */void transform(const byte block[64]);/* Encodes input (usigned long) into output (byte). */void encode(const bit32* input, byte* output, size_t length);/* Decodes input (byte) into output (usigned long). */void decode(const byte* input, bit32* output, size_t length);private:/* Flag for mark whether calculate finished. */bool finished;/* state (ABCD). */bit32 state[4];/* number of bits, low-order word first. */bit32 count[2];/* input buffer. */byte buffer[64];/* message digest. */byte digest[16];/* padding for calculate. */static const byte PADDING[64];/* Hex numbers. */static const char HEX_NUMBERS[16];
};#endif // MD5_H

/*** @file md5.cpp* @The implement of md5.* @author Jiewei Wei* @mail weijieweijerry@163* @github * @data Oct 19 2014**/#include "md5.h"/* Define the static member of MD5. */
const byte MD5::PADDING[64] = { 0x80 };
const char MD5::HEX_NUMBERS[16] = {'0', '1', '2', '3','4', '5', '6', '7','8', '9', 'a', 'b','c', 'd', 'e', 'f'
};/*** @Construct a MD5 object with a string.** @param {message} the message will be transformed.**/
MD5::MD5(const string& message) {finished = false;/* Reset number of bits. */count[0] = count[1] = 0;/* Initialization constants. */state[0] = 0x67452301;state[1] = 0xefcdab89;state[2] = 0x98badcfe;state[3] = 0x10325476;/* Initialization the object according to message. */init((const byte*)message.c_str(), message.length());
}/*** @Generate md5 digest.** @return the message-digest.**/
const byte* MD5::getDigest() {if (!finished) {finished = true;byte bits[8];bit32 oldState[4];bit32 oldCount[2];bit32 index, padLen;/* Save current state and count. */memcpy(oldState, state, 16);memcpy(oldCount, count, 8);/* Save number of bits */encode(count, bits, 8);/* Pad out to 56 mod 64. */index = (bit32)((count[0] >> 3) & 0x3f);padLen = (index < 56) ? (56 - index) : (120 - index);init(PADDING, padLen);/* Append length (before padding) */init(bits, 8);/* Store state in digest */encode(state, digest, 16);/* Restore current state and count. */memcpy(state, oldState, 16);memcpy(count, oldCount, 8);}return digest;
}/*** @Initialization the md5 object, processing another message block,* and updating the context.** @param {input} the input message.** @param {len} the number btye of message.**/
void MD5::init(const byte* input, size_t len) {bit32 i, index, partLen;finished = false;/* Compute number of bytes mod 64 */index = (bit32)((count[0] >> 3) & 0x3f);/* update number of bits */if ((count[0] += ((bit32)len << 3)) < ((bit32)len << 3)) {++count[1];}count[1] += ((bit32)len >> 29);partLen = 64 - index;/* transform as many times as possible. */if (len >= partLen) {memcpy(&buffer[index], input, partLen);transform(buffer);for (i = partLen; i + 63 < len; i += 64) {transform(&input[i]);}index = 0;} else {i = 0;}/* Buffer remaining input */memcpy(&buffer[index], &input[i], len - i);
}/*** @MD5 basic transformation. Transforms state based on block.** @param {block} the message block.*/
void MD5::transform(const byte block[64]) {bit32 a = state[0], b = state[1], c = state[2], d = state[3], x[16];decode(block, x, 64);/* Round 1 */FF (a, b, c, d, x[ 0], s11, 0xd76aa478);FF (d, a, b, c, x[ 1], s12, 0xe8c7b756);FF (c, d, a, b, x[ 2], s13, 0x242070db);FF (b, c, d, a, x[ 3], s14, 0xc1bdceee);FF (a, b, c, d, x[ 4], s11, 0xf57c0faf);FF (d, a, b, c, x[ 5], s12, 0x4787c62a);FF (c, d, a, b, x[ 6], s13, 0xa8304613);FF (b, c, d, a, x[ 7], s14, 0xfd469501);FF (a, b, c, d, x[ 8], s11, 0x698098d8);FF (d, a, b, c, x[ 9], s12, 0x8b44f7af);FF (c, d, a, b, x[10], s13, 0xffff5bb1);FF (b, c, d, a, x[11], s14, 0x895cd7be);FF (a, b, c, d, x[12], s11, 0x6b901122);FF (d, a, b, c, x[13], s12, 0xfd987193);FF (c, d, a, b, x[14], s13, 0xa679438e);FF (b, c, d, a, x[15], s14, 0x49b40821);/* Round 2 */GG (a, b, c, d, x[ 1], s21, 0xf61e2562);GG (d, a, b, c, x[ 6], s22, 0xc040b340);GG (c, d, a, b, x[11], s23, 0x265e5a51);GG (b, c, d, a, x[ 0], s24, 0xe9b6c7aa);GG (a, b, c, d, x[ 5], s21, 0xd62f105d);GG (d, a, b, c, x[10], s22,  0x2441453);GG (c, d, a, b, x[15], s23, 0xd8a1e681);GG (b, c, d, a, x[ 4], s24, 0xe7d3fbc8);GG (a, b, c, d, x[ 9], s21, 0x21e1cde6);GG (d, a, b, c, x[14], s22, 0xc33707d6);GG (c, d, a, b, x[ 3], s23, 0xf4d50d87);GG (b, c, d, a, x[ 8], s24, 0x455a14ed);GG (a, b, c, d, x[13], s21, 0xa9e3e905);GG (d, a, b, c, x[ 2], s22, 0xfcefa3f8);GG (c, d, a, b, x[ 7], s23, 0x676f02d9);GG (b, c, d, a, x[12], s24, 0x8d2a4c8a);/* Round 3 */HH (a, b, c, d, x[ 5], s31, 0xfffa3942);HH (d, a, b, c, x[ 8], s32, 0x8771f681);HH (c, d, a, b, x[11], s33, 0x6d9d6122);HH (b, c, d, a, x[14], s34, 0xfde5380c);HH (a, b, c, d, x[ 1], s31, 0xa4beea44);HH (d, a, b, c, x[ 4], s32, 0x4bdecfa9);HH (c, d, a, b, x[ 7], s33, 0xf6bb4b60);HH (b, c, d, a, x[10], s34, 0xbebfbc70);HH (a, b, c, d, x[13], s31, 0x289b7ec6);HH (d, a, b, c, x[ 0], s32, 0xeaa127fa);HH (c, d, a, b, x[ 3], s33, 0xd4ef3085);HH (b, c, d, a, x[ 6], s34,  0x4881d05);HH (a, b, c, d, x[ 9], s31, 0xd9d4d039);HH (d, a, b, c, x[12], s32, 0xe6db99e5);HH (c, d, a, b, x[15], s33, 0x1fa27cf8);HH (b, c, d, a, x[ 2], s34, 0xc4ac5665);/* Round 4 */II (a, b, c, d, x[ 0], s41, 0xf4292244);II (d, a, b, c, x[ 7], s42, 0x432aff97);II (c, d, a, b, x[14], s43, 0xab9423a7);II (b, c, d, a, x[ 5], s44, 0xfc93a039);II (a, b, c, d, x[12], s41, 0x655b59c3);II (d, a, b, c, x[ 3], s42, 0x8f0ccc92);II (c, d, a, b, x[10], s43, 0xffeff47d);II (b, c, d, a, x[ 1], s44, 0x85845dd1);II (a, b, c, d, x[ 8], s41, 0x6fa87e4f);II (d, a, b, c, x[15], s42, 0xfe2ce6e0);II (c, d, a, b, x[ 6], s43, 0xa3014314);II (b, c, d, a, x[13], s44, 0x4e0811a1);II (a, b, c, d, x[ 4], s41, 0xf7537e82);II (d, a, b, c, x[11], s42, 0xbd3af235);II (c, d, a, b, x[ 2], s43, 0x2ad7d2bb);II (b, c, d, a, x[ 9], s44, 0xeb86d391);state[0] += a;state[1] += b;state[2] += c;state[3] += d;
}/**
* @Encodes input (unsigned long) into output (byte).
*
* @param {input} usigned long.
*
* @param {output} byte.
*
* @param {length} the length of input.
*
*/
void MD5::encode(const bit32* input, byte* output, size_t length) {for (size_t i = 0, j = 0; j < length; ++i, j += 4) {output[j]= (byte)(input[i] & 0xff);output[j + 1] = (byte)((input[i] >> 8) & 0xff);output[j + 2] = (byte)((input[i] >> 16) & 0xff);output[j + 3] = (byte)((input[i] >> 24) & 0xff);}
}/*** @Decodes input (byte) into output (usigned long).** @param {input} bytes.** @param {output} unsigned long.** @param {length} the length of input.**/
void MD5::decode(const byte* input, bit32* output, size_t length) {for (size_t i = 0, j = 0; j < length; ++i, j += 4) {output[i] = ((bit32)input[j]) | (((bit32)input[j + 1]) << 8) |(((bit32)input[j + 2]) << 16) | (((bit32)input[j + 3]) << 24);}
}/*** @Convert digest to string value.** @return the hex string of digest.**/
string MD5::toStr() {const byte* digest_ = getDigest();string serve(16 << 1);for (size_t i = 0; i < 16; ++i) {int t = digest_[i];int a = t / 16;int b = t % 16;str.append(1, HEX_NUMBERS[a]);str.append(1, HEX_NUMBERS[b]);}return str;
}