列举5个Hash算法。
时间: 2024-02-26 18:55:59 浏览: 41
以下是5个常用的Hash算法:
1. MD5(Message Digest Algorithm 5):输出128位散列值,已被证明存在一些安全漏洞,不建议在安全性要求较高的场合使用。
2. SHA-1(Secure Hash Algorithm 1):输出160位散列值,已被证明存在一些安全漏洞,不建议在安全性要求较高的场合使用。
3. SHA-256(Secure Hash Algorithm 256):输出256位散列值,安全性较高,广泛应用于数字签名、认证等领域。
4. SHA-3(Secure Hash Algorithm 3):输出长度可变的散列值,是NIST于2015年发布的新一代散列算法,安全性和性能都有较大提升。
5. BLAKE2:输出长度可变的散列值,是一种高速、安全的散列算法,适用于各种数据完整性、验证和认证的应用场合。
相关问题
java写个局部敏感hash算法
局部敏感hash算法是一种图像检索技术,它用于将图像划分为多个局部特征,并将这些局部特征映射到对应的hash码。
下面是一个使用Java实现局部敏感hash算法的示例:
```
import java.awt.image.BufferedImage;
import java.util.Arrays;
public class LSH {
private int[][] hashCodes;
private int codeLength;
private int[][] matrix;
public LSH(BufferedImage image, int codeLength) {
this.codeLength = codeLength;
int width = image.getWidth();
int height = image.getHeight();
int[][] gray = new int[width][height];
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
gray[x][y] = getGray(image.getRGB(x, y));
}
}
int[][] dct = dct(gray);
matrix = getLSHMatrix(dct, codeLength);
hashCodes = getHashCodes(dct, matrix);
}
private int getGray(int rgb) {
int r = (rgb >> 16) & 0xff;
int g = (rgb >> 8) & 0xff;
int b = rgb & 0xff;
return (r + g + b) / 3;
}
private int[][] dct(int[][] f) {
int n = f.length;
int m = f[0].length;
double[][] F = new double[n][m];
for (int u = 0; u < n; u++) {
for (int v = 0; v < m; v++) {
double sum = 0.0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
sum += Math.cos((2 * i + 1) * u * Math.PI / (2 * n)) * Math.cos((2 * j + 1) * v * Math.PI / (2 * m)) * f[i][j];
}
}
sum *= (u == 0 ? 1.0 / Math.sqrt(n) : Math.sqrt(2.0 / n)) * (v == 0 ? 1.0 / Math.sqrt(m) : Math.sqrt(2.0 / m));
F[u][v] = sum;
}
}
int[][] dct = new int[n][m];
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
dct[i][j
用verilog 写一个 fpga Hash算法
这是一个非常宽泛的问题,因为 Hash 算法有很多种,而且每种算法的实现方式也不尽相同。下面是一个简单的例子,用 Verilog 实现 SHA-256 算法:
```verilog
module SHA256 (
input clk,
input rst,
input [511:0] message,
output reg [255:0] hash
);
// 定义常量
localparam [31:0] K[0:63] = '{32'h428a2f98, 32'h71374491, 32'hb5c0fbcf, 32'he9b5dba5, 32'h3956c25b, 32'h59f111f1, 32'h923f82a4, 32'hab1c5ed5,
32'hd807aa98, 32'h12835b01, 32'h243185be, 32'h550c7dc3, 32'h72be5d74, 32'h80deb1fe, 32'h9bdc06a7, 32'hc19bf174,
32'he49b69c1, 32'hefbe4786, 32'h0fc19dc6, 32'h240ca1cc, 32'h2de92c6f, 32'h4a7484aa, 32'h5cb0a9dc, 32'h76f988da,
32'h983e5152, 32'ha831c66d, 32'hb00327c8, 32'hbf597fc7, 32'hc6e00bf3, 32'hd5a79147, 32'h06ca6351, 32'h14292967,
32'h27b70a85, 32'h2e1b2138, 32'h4d2c6dfc, 32'h53380d13, 32'h650a7354, 32'h766a0abb, 32'h81c2c92e, 32'h92722c85,
32'ha2bfe8a1, 32'ha81a664b, 32'hc24b8b70, 32'hc76c51a3, 32'hd192e819, 32'hd6990624, 32'hf40e3585, 32'h106aa070,
32'h19a4c116, 32'h1e376c08, 32'h2748774c, 32'h34b0bcb5, 32'h391c0cb3, 32'h4ed8aa4a, 32'h5b9cca4f, 32'h682e6ff3,
32'h748f82ee, 32'h78a5636f, 32'h84c87814, 32'h8cc70208, 32'ha4506ceb, 32'hbef9a3f7, 32'hc67178f2};
// 定义变量
reg [31:0] h[0:7];
reg [31:0] w[0:63];
reg [31:0] a, b, c, d, e, f, g, h_temp;
reg [31:0] s0, s1, maj, ch, temp1, temp2;
// 初始化哈希值
initial begin
h[0] = 32'h6a09e667;
h[1] = 32'hbb67ae85;
h[2] = 32'h3c6ef372;
h[3] = 32'ha54ff53a;
h[4] = 32'h510e527f;
h[5] = 32'h9b05688c;
h[6] = 32'h1f83d9ab;
h[7] = 32'h5be0cd19;
end
// 计算 SHA-256 算法
always @(posedge clk) begin
if (rst) begin
h[0] <= 32'h6a09e667;
h[1] <= 32'hbb67ae85;
h[2] <= 32'h3c6ef372;
h[3] <= 32'ha54ff53a;
h[4] <= 32'h510e527f;
h[5] <= 32'h9b05688c;
h[6] <= 32'h1f83d9ab;
h[7] <= 32'h5be0cd19;
end else begin
// 将 512 位消息分为 16 个 32 位消息块
for (int i = 0; i < 16; i = i + 1) begin
w[i] = message[i*32 +: 32];
end
// 将 16 个 32 位消息块扩展为 64 个 32 位消息块
for (int i = 16; i < 64; i = i + 1) begin
s0 = w[i-15] ^ (w[i-15] >>> 7) ^ (w[i-15] >>> 18) ^ (w[i-15] >>> 3);
s1 = w[i-2] ^ (w[i-2] >>> 17) ^ (w[i-2] >>> 19) ^ (w[i-2] >>> 10);
w[i] = w[i-16] + s0 + w[i-7] + s1;
end
// 初始化哈希值
a = h[0];
b = h[1];
c = h[2];
d = h[3];
e = h[4];
f = h[5];
g = h[6];
h_temp = h[7];
// 进行 64 轮计算
for (int i = 0; i < 64; i = i + 1) begin
s1 = e >>> 6 ^ e >>> 11 ^ e >>> 25;
ch = (e & f) ^ (~e & g);
temp1 = h_temp + s1 + ch + K[i] + w[i];
s0 = a >>> 2 ^ a >>> 13 ^ a >>> 22;
maj = (a & b) ^ (a & c) ^ (b & c);
temp2 = s0 + maj;
h_temp = g;
g = f;
f = e;
e = d + temp1;
d = c;
c = b;
b = a;
a = temp1 + temp2;
end
// 更新哈希值
h[0] = h[0] + a;
h[1] = h[1] + b;
h[2] = h[2] + c;
h[3] = h[3] + d;
h[4] = h[4] + e;
h[5] = h[5] + f;
h[6] = h[6] + g;
h[7] = h[7] + h_temp;
end
// 输出哈希值
hash = {h[0], h[1], h[2], h[3], h[4], h[5], h[6], h[7]};
end
endmodule
```
这个例子中,我们使用了 Verilog 语言实现 SHA-256 算法。具体来说,我们定义了输入消息、输出哈希值和状态寄存器(也就是 SHA-256 算法中的 A、B、C、D、E、F、G 和 H),并且在时钟上升沿时计算哈希值。
需要注意的是,这个例子只是 SHA-256 算法的一个简单实现,并不是最优化的实现方式。实际上,在 FPGA 上实现 Hash 算法需要考虑很多因素,比如时钟频率、资源占用和延迟等。因此,我们需要根据具体的应用场景来选择最合适的实现方式。