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。
package com.ss.util.secret;public class SHA1Utils {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());}
}
admin的SHA1的值为：d033e22ae348aeb5660fc2140aec35850c4da997,length=40