上篇相关文章讲了怎么从JNI里面拿到数字字符串，这次具体实现以下怎么在C里面加密，并且返回。在此基础上，我们进行操作。
这次主要在C里面使用base64和md5的方式。Java里面md5和base64加密很简单。C里面，暂时需要别人的库。这里我直接在github上找的直接先复制粘贴过来。需要的自行复制，不需要的跳过，直接进入下一环节。
md5.java 文件

public class MD5Utils {
    /**
     * 16进制的字符数组
     */
    private static final String[] hexDigits = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d",
            "e", "f"};

    /**
     * 对字符串进行MD5加密
     *
     * @param content
     * @return
     */
    public static String encryptedByMD5(String content) {
        String result = null;
        try {
            result = content;
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            messageDigest.update(result.getBytes());
            result = byteArrayToHexString(messageDigest.digest());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result.toUpperCase(Locale.getDefault());
    }

    /**
     * 32位加密
     * @param content
     * @return
     */
    public static String encryptedByMD5_32(String content) {
        String re_md5 = new String();
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(content.getBytes());
            byte b[] = md.digest();

            int i;

            StringBuffer buf = new StringBuffer("");
            for (int offset = 0; offset < b.length; offset++) {
                i = b[offset];
                if (i < 0) {
                    i += 256;
                }
                if (i < 16) {
                    buf.append("0");
                }
                buf.append(Integer.toHexString(i));
            }
            re_md5 = buf.toString();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return re_md5;

    }


    /**
     * 转换字节数组为16进制字符串
     *
     * @param bytes 字节数组
     * @return
     */
    private static String byteArrayToHexString(byte[] bytes) {
        StringBuilder stringBuilder = new StringBuilder();
        for (byte tem : bytes) {
            stringBuilder.append(byteToHexString(tem));
        }
        return stringBuilder.toString();
    }

    /**
     * 转换byte到16进制
     *
     * @param b 要转换的byte
     * @return 16进制对应的字符
     */
    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n = 256 + n;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }
}

base64.h的文件

/**
 * `b64.h' - b64
 *
 * copyright (c) 2014 joseph werle
 */

#ifndef B64_H
#define B64_H 1

//#include <cwchar>

/**
 * Base64 index table.
 */

static const char b64_table[] = {
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
  'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
  'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
  'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
  'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
  'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
  'w', 'x', 'y', 'z', '0', '1', '2', '3',
  '4', '5', '6', '7', '8', '9', '+', '/'
};

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Encode `unsigned char *' source with `size_t' size.
 * Returns a `char *' base64 encoded string.
 */

char *
b64_encode (const unsigned char *, size_t);

/**
 * Dencode `char *' source with `size_t' size.
 * Returns a `unsigned char *' base64 decoded string.
 */
unsigned char *
b64_decode (const char *, size_t);

/**
 * Dencode `char *' source with `size_t' size.
 * Returns a `unsigned char *' base64 decoded string + size of decoded string.
 */
unsigned char *
b64_decode_ex (const char *, size_t, size_t *);

#ifdef __cplusplus
}
#endif
#endif

bas64.c文件

/**
 * `encode.c' - b64
 *
 * copyright (c) 2014 joseph werle
 */

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include "base64.h"



char *
b64_encode (const unsigned char *src, size_t len) {
  int i = 0;
  int j = 0;
  char *enc = NULL;
  size_t size = 0;
  unsigned char buf[4];
  unsigned char tmp[3];

  // alloc
  enc = (char *) malloc(0);
  if (NULL == enc) { return NULL; }

  // parse until end of source
  while (len--) {
    // read up to 3 bytes at a time into `tmp'
    tmp[i++] = *(src++);

    // if 3 bytes read then encode into `buf'
    if (3 == i) {
      buf[0] = (tmp[0] & 0xfc) >> 2;
      buf[1] = ((tmp[0] & 0x03) << 4) + ((tmp[1] & 0xf0) >> 4);
      buf[2] = ((tmp[1] & 0x0f) << 2) + ((tmp[2] & 0xc0) >> 6);
      buf[3] = tmp[2] & 0x3f;

      // allocate 4 new byts for `enc` and
      // then translate each encoded buffer
      // part by index from the base 64 index table
      // into `enc' unsigned char array
      enc = (char *) realloc(enc, size + 4);
      for (i = 0; i < 4; ++i) {
        enc[size++] = b64_table[buf[i]];
      }

      // reset index
      i = 0;
    }
  }

  // remainder
  if (i > 0) {
    // fill `tmp' with `\0' at most 3 times
    for (j = i; j < 3; ++j) {
      tmp[j] = '\0';
    }

    // perform same codec as above
    buf[0] = (tmp[0] & 0xfc) >> 2;
    buf[1] = ((tmp[0] & 0x03) << 4) + ((tmp[1] & 0xf0) >> 4);
    buf[2] = ((tmp[1] & 0x0f) << 2) + ((tmp[2] & 0xc0) >> 6);
    buf[3] = tmp[2] & 0x3f;

    // perform same write to `enc` with new allocation
    for (j = 0; (j < i + 1); ++j) {
      enc = (char *) realloc(enc, size + 1);
      enc[size++] = b64_table[buf[j]];
    }

    // while there is still a remainder
    // append `=' to `enc'
    while ((i++ < 3)) {
      enc = (char *) realloc(enc, size + 1);
      enc[size++] = '=';
    }
  }

  // Make sure we have enough space to add '\0' character at end.
  enc = (char *) realloc(enc, size + 1);
  enc[size] = '\0';

  return enc;
}


unsigned char *
b64_decode(const char *src, size_t len) {
  return b64_decode_ex(src, len, NULL);
}

unsigned char *
b64_decode_ex(const char *src, size_t len, size_t *decsize) {
  int i = 0;
  int j = 0;
  int l = 0;
  size_t size = 0;
  unsigned char *dec = NULL;
  unsigned char buf[3];
  unsigned char tmp[4];

  // alloc
  dec = (unsigned char *) malloc(0);
  if (NULL == dec) { return NULL; }

  // parse until end of source
  while (len--) {
    // break if char is `=' or not base64 char
    if ('=' == src[j]) { break; }
    if (!(isalnum(src[j]) || '+' == src[j] || '/' == src[j])) { break; }

    // read up to 4 bytes at a time into `tmp'
    tmp[i++] = src[j++];

    // if 4 bytes read then decode into `buf'
    if (4 == i) {
      // translate values in `tmp' from table
      for (i = 0; i < 4; ++i) {
        // find translation char in `b64_table'
        for (l = 0; l < 64; ++l) {
          if (tmp[i] == b64_table[l]) {
            tmp[i] = l;
            break;
          }
        }
      }

      // decode
      buf[0] = (tmp[0] << 2) + ((tmp[1] & 0x30) >> 4);
      buf[1] = ((tmp[1] & 0xf) << 4) + ((tmp[2] & 0x3c) >> 2);
      buf[2] = ((tmp[2] & 0x3) << 6) + tmp[3];

      // write decoded buffer to `dec'
      dec = (unsigned char *) realloc(dec, size + 3);
      for (i = 0; i < 3; ++i) {
        dec[size++] = buf[i];
      }

      // reset
      i = 0;
    }
  }

  // remainder
  if (i > 0) {
    // fill `tmp' with `\0' at most 4 times
    for (j = i; j < 4; ++j) {
      tmp[j] = '\0';
    }

    // translate remainder
    for (j = 0; j < 4; ++j) {
      // find translation char in `b64_table'
      for (l = 0; l < 64; ++l) {
        if (tmp[j] == b64_table[l]) {
          tmp[j] = l;
          break;
        }
      }
    }

    // decode remainder
    buf[0] = (tmp[0] << 2) + ((tmp[1] & 0x30) >> 4);
    buf[1] = ((tmp[1] & 0xf) << 4) + ((tmp[2] & 0x3c) >> 2);
    buf[2] = ((tmp[2] & 0x3) << 6) + tmp[3];

    // write remainer decoded buffer to `dec'
    dec = (unsigned char *) realloc(dec, size + (i - 1));
    for (j = 0; (j < i - 1); ++j) {
      dec[size++] = buf[j];
    }
  }

  // Make sure we have enough space to add '\0' character at end.
  dec = (unsigned char *) realloc(dec, size + 1);
  dec[size] = '\0';

  // Return back the size of decoded string if demanded.
  if (decsize != NULL) *decsize = size;

  return dec;
}

md5.h的文件

//
// Created by wei on 16-11-28.
//

//#ifndef ENCRYPTJNI_MD5_H_H
//#define ENCRYPTJNI_MD5_H_H
//


#include <stdint.h>

/* POINTER defines a generic pointer type */
typedef unsigned char *POINTER;

/* UINT2 defines a two byte word */
typedef unsigned short int UINT2;

/* UINT4 defines a four byte word */
//===============================bugfix：arm64下跟java 下的md5接过不同的问题===============
//typedef unsigned long int UINT4;// 这个已经废弃 否则导致 armv864下出现跟java下MD5不同的问题
typedef uint32_t UINT4;

/* PROTO_LIST is defined depending on how PROTOTYPES is defined above.
If using PROTOTYPES, then PROTO_LIST returns the list, otherwise it
  returns an empty list.
 */

/* MD5 context. */
typedef struct tagMD5_CTX{
    UINT4 state[4];                                   /* state (ABCD) */
    UINT4 count[2];        /* number of bits, modulo 2^64 (lsb first) */
    unsigned char buffer[64];                         /* input buffer */
} MD5_CTX;
#ifdef __cplusplus
extern "C" {
#endif
void MD5Init (MD5_CTX *context);
void MD5Update (MD5_CTX *context,unsigned char *input,unsigned int inputLen);
void MD5Final (unsigned char digest[16], MD5_CTX *context);

static void MD5Transform (UINT4 state[4], unsigned char block[64]);
static void Encode (unsigned char *output, UINT4 *input, unsigned int len);
static void Decode (UINT4 *output, unsigned char *input, unsigned int len);
static void MD5_memcpy (POINTER output, POINTER input, unsigned int len);
static void MD5_memset (POINTER output, int value, unsigned int len);

#ifdef __cplusplus
}
#endif

//#endif //ENCRYPTJNI_MD5_H_H

md5.c的文件

//
// Created by wei on 16-11-28.
//
#include "md5.h"


/* Constants for MD5Transform routine.
 */

#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

static unsigned char PADDING[64] = {
        0x80, 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, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/* F, G, H and I are basic MD5 functions.
 */
#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 rotates x left n bits.
 */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
Rotation is separate from addition to prevent recomputation.
 */
#define FF(a, b, c, d, x, s, ac) { \
 (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }
#define GG(a, b, c, d, x, s, ac) { \
 (a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }
#define HH(a, b, c, d, x, s, ac) { \
 (a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }
#define II(a, b, c, d, x, s, ac) { \
 (a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }

/* MD5 initialization. Begins an MD5 operation, writing a new context.
 */
void MD5Init (MD5_CTX *context)
{
    context->count[0] = context->count[1] = 0;
    /* Load magic initialization constants.
  */
    context->state[0] = 0x67452301;
    context->state[1] = 0xefcdab89;
    context->state[2] = 0x98badcfe;
    context->state[3] = 0x10325476;
}

/* MD5 block update operation. Continues an MD5 message-digest
  operation, processing another message block, and updating the
  context.
 */
void MD5Update (MD5_CTX *context,unsigned char *input,unsigned int inputLen)
{
    unsigned int i, index, partLen;

    /* Compute number of bytes mod 64 */
    index = (unsigned int)((context->count[0] >> 3) & 0x3F);

    /* Update number of bits */
    if ((context->count[0] += ((UINT4)inputLen << 3))
        < ((UINT4)inputLen << 3))
        context->count[1]++;
    context->count[1] += ((UINT4)inputLen >> 29);

    partLen = 64 - index;

    /* Transform as many times as possible.
  */
    if (inputLen >= partLen) {
        MD5_memcpy
                ((POINTER)&context->buffer[index], (POINTER)input, partLen);
        MD5Transform (context->state, context->buffer);

        for (i = partLen; i + 63 < inputLen; i += 64)
            MD5Transform (context->state, &input[i]);

        index = 0;
    }
    else
        i = 0;

    /* Buffer remaining input */
    MD5_memcpy
            ((POINTER)&context->buffer[index], (POINTER)&input[i],
             inputLen-i);
}

/* MD5 finalization. Ends an MD5 message-digest operation, writing the
  the message digest and zeroizing the context.
 */
void MD5Final (unsigned char digest[16], MD5_CTX *context)
{
    unsigned char bits[8];
    unsigned int index, padLen;

    /* Save number of bits */
    Encode (bits, context->count, 8);

    /* Pad out to 56 mod 64.
  */
    index = (unsigned int)((context->count[0] >> 3) & 0x3f);
    padLen = (index < 56) ? (56 - index) : (120 - index);
    MD5Update (context, PADDING, padLen);

    /* Append length (before padding) */
    MD5Update (context, bits, 8);

    /* Store state in digest */
    Encode (digest, context->state, 16);

    /* Zeroize sensitive information.
  */
    MD5_memset ((POINTER)context, 0, sizeof (*context));
}

/* MD5 basic transformation. Transforms state based on block.
 */
static void MD5Transform (UINT4 state[4], unsigned char block[64])
{
    UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

    Decode (x, block, 64);

    /* Round 1 */
    FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
    FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
    FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
    FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
    FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
    FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
    FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
    FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
    FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
    FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
    FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
    FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
    FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
    FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
    FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
    FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */

    /* Round 2 */
    GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
    GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
    GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
    GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
    GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
    GG (d, a, b, c, x[10], S22,  0x2441453); /* 22 */
    GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
    GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
    GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
    GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
    GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
    GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
    GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
    GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
    GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
    GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */

    /* Round 3 */
    HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
    HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
    HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
    HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
    HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
    HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
    HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
    HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
    HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
    HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
    HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
    HH (b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */
    HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
    HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
    HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
    HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */

    /* Round 4 */
    II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
    II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
    II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
    II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
    II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
    II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
    II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
    II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
    II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
    II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
    II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
    II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
    II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
    II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
    II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
    II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;

    /* Zeroize sensitive information.
     */
    MD5_memset ((POINTER)x, 0, sizeof (x));
}

/* Encodes input (UINT4) into output (unsigned char). Assumes len is
  a multiple of 4.
 */
static void Encode (unsigned char *output, UINT4 *input, unsigned int len)
{
    unsigned int i, j;

    for (i = 0, j = 0; j < len; i++, j += 4) {
        output[j] = (unsigned char)(input[i] & 0xff);
        output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
        output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
        output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
    }
}

/* Decodes input (unsigned char) into output (UINT4). Assumes len is
  a multiple of 4.
 */
static void Decode (UINT4 *output, unsigned char *input, unsigned int len)
{
    unsigned int i, j;

    for (i = 0, j = 0; j < len; i++, j += 4)
        output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |
                    (((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
}

/* Note: Replace "for loop" with standard memcpy if possible.
 */

static void MD5_memcpy (POINTER output, POINTER input, unsigned int len)
{
    unsigned int i;

    for (i = 0; i < len; i++)
        output[i] = input[i];
}

/* Note: Replace "for loop" with standard memset if possible.
 */
static void MD5_memset (POINTER output, int value, unsigned int len)
{
    unsigned int i;

    for (i = 0; i < len; i++)
        ((char *)output)[i] = (char)value;
}

好了文件都复制完成之后，咱们进入正题。
我们设计一个加密方式，几个字段了解一下。
没加密之前的String originalString ="xxx" (xxx代表你输入需要加密的字符串
这里before的字符串和after的字符串 暂时这么定义，你也可以用你自己需要的
字符串String before="info_"
字符串String after="after"
原始的字段开始加上before，末尾加上after，然后对此增加后的字符串进行base64加密，加密之后，md5加密这个base64加密后的。然后后面跟上一个当前时间的md5加密值，最后再整体md5加密一下。具体的java代码如下

 public String getUrl(String originalString, String before, String after) {
        String temp = null;
        try {
            temp = new String(Base64.encode((before + originalString + after).getBytes("utf-8"), Base64.NO_WRAP), "utf-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        String sign = MD5Utils.encryptedByMD5_32(MD5Utils.encryptedByMD5_32(temp) + MD5Utils.encryptedByMD5_32(currentTime));
        return sign;
}

JNI层面的代码如下

JNIEXPORT jstring JNICALL
Java_com_boxun_zhao_jni_NativeUtil_getSign(JNIEnv *env, jclass type, jstring token_,
                                           jstring time_) {
    const char *token = env->GetStringUTFChars(token_, 0);
    const char *time = env->GetStringUTFChars(time_, 0);
    string addedString(token);
    addedString.insert(0, BEFORE);
    addedString.insert(addedString.length(), AFTER);
    char *token_b64 = b64_encode((const unsigned char *) addedString.c_str(), addedString.length());
    char destToken[32] = {0};
    getMd5String((unsigned char *) token_b64, destToken);
    string md5Token(destToken);
    char destTime[32] = {0};
    getMd5String((unsigned char *) time, destTime);
    string md5Time(destTime);
    md5Token.insert(md5Token.length(), md5Time);
    char signArray[32] = {0};
    getMd5String((unsigned char *) md5Token.c_str(), signArray);
    env->ReleaseStringUTFChars(token_, token);
    env->ReleaseStringUTFChars(time_, time);
    return env->NewStringUTF(signArray);
}

代码里面
BEFORE和AFTER是定义在C里面的全局变量这样java端不需要传递进来
b64_encode是之前复制的base64文件里面的方法，此外需要额外自己写一个调用Md5的方法

static const char *BEFORE = "info_";
static const char *AFTER = "after";

JNI内部调用三方MD5加密部分

void getMd5String(unsigned char *input, char charArray[32]) {
    MD5_CTX *ctx = new MD5_CTX();
    MD5Init(ctx);
    MD5Update(ctx, input, strlen((const char *) input));
    unsigned char dest[16] = {0};
    MD5Final(dest, ctx);
    for (int i = 0; i < 16; i++) {
        sprintf(charArray, "%s%02x", charArray, dest[i]);
    }
}

此外代码部分基本完成，下面就是测试了，注意相关文件引入，还有包名，这个当时写的时候包名的问题吃了不少亏

String testString="eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiIsImtpZCI6IjcifQ.eyJ1aWQiOiI4NzM2OTk3NyIsImNvZGUiOiJmZWl4dW4qMTIzLlNIXzgxMjgxMzQiLCJ0eXBlIjoiYWNjZXNzX3Rva2VuIiwiaXNzIjoiUGhpY29tbSIsIm5iZiI6MTUzMjMyODkyNSwiZXhwIjoxNTMyNDU4NTI1LCJyZWZyZXNoVGltZSI6IjIwMTgtMDctMjQgMDI6NTU6MjUifQ.Pe8DupJUpXzbcrGDN2yjhZ7K4qXYMfCJOCxTEBvhCcE\n",
currentTime = String.valueOf(System.currentTimeMillis());
TextView tv = (TextView) findViewById(R.id.sample_text);
tv.setText("native加密的结果"+NativeUtil.getSign(testString,currentTime));
        Log.e("zbx", "java加密的结果"+getUrl(testString, "info", "after_"));

测试结果

image.png

到这里算是初步完成，因为如果这样的话还不是特别安全，别人拿到你编译的so，知道里面的方法名直接调用还是不太安全，这里可以增加一个安卓包的签名校验，之前都是Java调用C，签名校验的时候需要C调用Java，这个在Android加密（三）去写了。
平时比较懒，也比较忙。这段时间比较空，把之前一直想写写了一半的一些总结陆续发布出来，算是技术交流了，如果有什么写的不对或者讲的不对的，欢迎批评指导。