不可逆加密算法之SHA1，Java实现

1.简介
SHA即安全哈希算法（Secure Hash Algorithm）主要适用于数字签名标准（Digital Signature Standard DSS）里面定义的数字签名算法（Digital Signature Algorithm DSA）。对于长度小于2^64位的消息，SHA1会产生一个160位的消息摘要。当接收到消息的时候，这个消息摘要可以用来验证数据的完整性。在传输的过程中，数据很可能会发生变化，那么这时候就会产生不同的消息摘要。
　　SHA1有如下特性：不可以从消息摘要中复原信息；两个不同的消息不会产生同样的消息摘要。
2.Java实现代码

public class SHA1Util {
    private static final boolean hexcase = false;   
    private static final String b64pad = "=";   
    private static final int chrsz = 8;   
       
    //得到字符串SHA-1值的方法   
    public static String hex_sha1(String s)    
    {    
        s = (s == null) ? "" : s;    
        return binb2hex(core_sha1(str2binb(s), s.length() * chrsz));    
    }    
       
    public static String b64_hmac_sha1(String key, String data)    
    {    
        return binb2b64(core_hmac_sha1(key, data));    
    }    
       
    public static String b64_sha1(String s)    
    {    
        s = (s==null) ? "" : s;    
        return binb2b64(core_sha1(str2binb(s), s.length() * chrsz));    
    }    
       
    private static String binb2b64(int[] binarray)    
    {    
        String tab = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789+/";    
        String str = "";    
        binarray = strechbinarray(binarray, binarray.length * 4);    
           
        for (int i = 0; i < binarray.length * 4; i += 3)    
        {    
            int triplet = (((binarray[i >> 2] >> 8 * (3 - i % 4)) & 0xff) << 16)    
                | (((binarray[i + 1 >> 2] >> 8 * (3 - (i + 1) % 4)) & 0xff) << 8)    
                | ((binarray[i + 2 >> 2] >> 8 * (3 - (i + 2) % 4)) & 0xff);    
               
            for (int j = 0; j < 4; j++)    
            {    
                if (i * 8 + j * 6 > binarray.length * 32)    
                {   
                    str += b64pad;    
                }   
                else    
                {   
                    str += tab.charAt((triplet >> 6 * (3 - j)) & 0x3f);    
                }   
            }    
        }    
           
        return cleanb64str(str);    
    }    
       
    private static String binb2hex(int[] binarray)    
    {    
        String hex_tab = hexcase ? "0123456789abcdef" : "0123456789abcdef";    
        String str = "";    
           
        for (int i = 0; i < binarray.length * 4; i++)    
        {    
            char a = (char) hex_tab.charAt((binarray[i >> 2] >> ((3 - i % 4) * 8 + 4)) & 0xf);    
            char b = (char) hex_tab.charAt((binarray[i >> 2] >> ((3 - i % 4) * 8)) & 0xf);    
            str += (new Character(a).toString() + new Character(b).toString());    
        }    
           
        return str;    
    }    
       
    private static String binb2str(int[] bin)    
    {    
        String str = "";    
        int mask = (1 << chrsz) - 1;    
           
        for (int i = 0; i < bin.length * 32; i += chrsz)    
        {   
            str += (char) ((bin[i >> 5] >>> (24 - i % 32)) & mask);    
        }   
           
        return str;    
    }    
       
    private static int bit_rol(int num, int cnt)    
    {    
        return (num << cnt) | (num >>> (32 - cnt));    
    }    
       
    private static String cleanb64str(String str)    
    {    
        str = (str==null) ? "" : str;    
        int len = str.length();    
           
        if (len <= 1)    
        {   
            return str;    
        }   
           
        char trailchar = str.charAt(len - 1);    
        String trailstr="";    
           
        for (int i=len-1;i>=0 && str.charAt(i)==trailchar;i--)    
        {   
            trailstr += str.charAt(i);    
        }   
           
        return str.substring(0,str.indexOf(trailstr));    
    }    
       
    private static int[] complete216(int[] oldbin)    
    {    
        if (oldbin.length >= 16)    
        {   
            return oldbin;    
        }   
           
        int[] newbin = new int[16 - oldbin.length];    
           
        for (int i = 0; i<newbin.length; newbin[i]=0,i++);    
           
        return concat(oldbin, newbin);    
    }    
       
    private static int[] concat(int[] oldbin, int[] newbin)    
    {    
        int[] retval = new int[oldbin.length + newbin.length];    
           
        for (int i = 0; i < (oldbin.length + newbin.length); i++)    
        {    
            if (i < oldbin.length)    
            {   
                retval[i] = oldbin[i];    
            }   
            else    
            {   
                retval[i] = newbin[i - oldbin.length];    
            }   
        }    
           
        return retval;    
    }    
       
    private static int[] core_hmac_sha1(String key, String data)    
    {    
        key = (key == null) ? "" : key;    
        data = (data == null) ? "" : data;    
        int[] bkey = complete216(str2binb(key));    
           
        if (bkey.length > 16)    
        {   
            bkey = core_sha1(bkey, key.length() * chrsz);    
        }   
           
        int[] ipad = new int[16];    
        int[] opad = new int[16];    
           
        for (int i = 0; i < 16; ipad[i] = 0, opad[i] = 0, i++);    
           
        for (int i = 0; i < 16; i++)    
        {    
            ipad[i] = bkey[i] ^ 0x36363636;    
            opad[i] = bkey[i] ^ 0x5c5c5c5c;    
        }    
           
        int[] hash = core_sha1(concat(ipad, str2binb(data)), 512 + data.length() * chrsz);    
           
        return core_sha1(concat(opad, hash), 512 + 160);    
    }    
       
    private static int[] core_sha1(int[] x, int len)    
    {    
        int size = (len >> 5);    
        x = strechbinarray(x, size);    
        x[len >> 5] |= 0x80 << (24 - len % 32);    
        size = ((len + 64 >> 9) << 4) + 15;    
        x = strechbinarray(x, size);    
        x[((len + 64 >> 9) << 4) + 15] = len;    
           
        int[] w = new int[80];    
        int a = 1732584193;    
        int b = -271733879;    
        int c = -1732584194;    
        int d = 271733878;    
        int e = -1009589776;    
           
        for (int i = 0; i < x.length; i += 16)    
        {    
            int olda = a;    
            int oldb = b;    
            int oldc = c;    
            int oldd = d;    
            int olde = e;    
               
            for (int j = 0; j < 80; j++)    
            {    
                if (j < 16)    
                {   
                    w[j] = x[i + j];    
                }   
                else    
                {   
                    w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1);    
                }   
                   
                int t = safe_add( safe_add(rol(a, 5), sha1_ft(j, b, c, d)), safe_add(safe_add(e, w[j]), sha1_kt(j)));    
                   
                e = d;    
                d = c;    
                c = rol(b, 30);    
                b = a;    
                a = t;    
            }    
               
            a = safe_add(a, olda);    
            b = safe_add(b, oldb);    
            c = safe_add(c, oldc);    
            d = safe_add(d, oldd);    
            e = safe_add(e, olde);    
        }    
           
        int[] retval = new int[5];    
           
        retval[0] = a;    
        retval[1] = b;    
        retval[2] = c;    
        retval[3] = d;    
        retval[4] = e;    
           
        return retval;    
    }    
       
    private static void dotest()    
    {    
        String key="key";    
        String data="data";    
        System.out.println("hex_sha1(" + data + ")=" + hex_sha1(data));    
        System.out.println("b64_sha1(" + data + ")=" + b64_sha1(data));    
        System.out.println("str_sha1(" + data + ")=" + str_sha1(data));    
        System.out.println("hex_hmac_sha1(" + key + "," + data + ")=" + hex_hmac_sha1(key, data));    
        System.out.println("b64_hmac_sha1(" + key + "," + data + ")=" + b64_hmac_sha1(key, data));    
        System.out.println("str_hmac_sha1(" + key + "," + data + ")=" + str_hmac_sha1(key, data));    
    }    
       
    public static String hex_hmac_sha1(String key, String data)    
    {    
        return binb2hex(core_hmac_sha1(key, data));    
    }    
       
    private static int rol(int num, int cnt)    
    {    
        return (num << cnt) | (num >>> (32 - cnt));    
    }    
       
    private static int safe_add(int x, int y)    
    {    
        int lsw = (int) (x & 0xffff) + (int) (y & 0xffff);    
        int msw = (x >> 16) + (y >> 16) + (lsw >> 16);    
           
        return (msw << 16) | (lsw & 0xffff);    
    }    
       
    private static int sha1_ft(int t, int b, int c, int d)    
    {    
        if (t < 20)    
            return (b & c) | ((~b) & d);    
           
        if (t < 40)    
            return b ^ c ^ d;    
           
        if (t < 60)    
            return (b & c) | (b & d) | (c & d);    
           
        return b ^ c ^ d;    
    }    
       
    private static int sha1_kt(int t)    
    {    
        return (t < 20) ? 1518500249 : (t < 40) ? 1859775393 : (t < 60) ? -1894007588 : -899497514;    
    }    
       
    private static boolean sha1_vm_test()    
    {    
        return hexcase ? hex_sha1("abc").equals("a9993e364706816aba3e25717850c26c9cd0d89d") : hex_sha1("abc").equals("a9993e364706816aba3e25717850c26c9cd0d89d");    
    }    
       
    public static String str_hmac_sha1(String key, String data)    
    {    
        return binb2str(core_hmac_sha1(key, data));    
    }    
       
    public static String str_sha1(String s)    
    {    
        s = (s == null) ? "" : s;    
           
        return binb2str(core_sha1(str2binb(s), s.length() * chrsz));    
    }    
       
    private static int[] str2binb(String str)    
    {    
        str = (str==null) ? "" : str;    
           
        int[] tmp = new int[str.length() * chrsz];    
        int mask = (1 << chrsz) - 1;    
           
        for(int i = 0; i < str.length() * chrsz; i += chrsz)    
        {   
            tmp[i>>5] |= ( (int)(str.charAt(i / chrsz)) & mask) << (24 - i%32);    
        }   
           
        int len = 0;    
        for (int i=0;i<tmp.length&&tmp[i]!=0;i++,len++);    
           
        int[] bin = new int[len];    
           
        for (int i=0;i<len;i++)    
        {   
            bin[i] = tmp[i];    
        }   
           
        return bin;    
    }    
       
    private static int[] strechbinarray(int[] oldbin, int size)    
    {    
        int currlen = oldbin.length;    
           
        if (currlen >= size + 1)    
        {   
            return oldbin;    
        }   
           
        int[] newbin = new int[size + 1];    
        for (int i = 0; i < size; newbin[i] = 0, i++);    
           
        for (int i = 0; i < currlen; i++)    
        {   
            newbin[i] = oldbin[i];    
        }   
           
        return newbin;    
    }    
       
    public static void main(String args[])   
    {   
        System.out.println("admin的SHA1的值为："+hex_sha1("admin") + ",length="+hex_sha1("admin").length());   
    }   
}