给定长度为N的字符串S ，任务是查找给定字符串S的SHA-512哈希值。
例子：
Input: S = “GeeksforGeeks”
Output: acc10c4e0b38617f59e88e49215e2e894afaee5ec948c2af6f44039f03c9fe47a9210e01d5cd926c142bdc9179c2ad30f927a8faf69421ff60a5eaddcf8cb9c
Input: S = “hello world”
Output:
309ecc489c12d6eb4cc40f50c902f2b4d0ed77ee511a7c7a9bcd3ca86d4cd86f989dd35bc5ff499670da34255b45b0cfd830e81f605dcf7dc5542e93ae9cd76f
方法：请按照以下步骤解决问题：
- 将给定的字符串转换为二进制形式。
- 在字符串追加‘1’ ，然后连续追加‘ 0’，直到字符串的长度小于((N％(1024 – 128)))为止。
- 在字符串S中添加N的128位二进制表示形式。
- 找到大小为1024的块数并将其存储在变量中，例如，块数为N / 1024 。
- 将字符串S分成64个字符的16个块。
- 通过执行以下操作，将块的数量扩展到80 ：
- 迭代范围[ 16，80 ] ，然后找到4个值，分别是WordA，WordB，WordC，WordD，如下所示：
- WordA = rotation_right(Message [g – 2]，19)^ rotation_right(Message [g – 2]，61)^ shift_right(Message [g – 2]，6) 。
- WordB =消息[g – 7] 。
- WordC = rotation_right(Message [g – 15]，1)^ rotation_right(Message [g – 15]，8)^ shift_right(Message [g – 15]，7) 。
- WordD =消息[g – 16] 。
- 将Message [g]的值更新为(WordA + WordB + WordC + WordD) 。
- 迭代范围[ 16，80 ] ，然后找到4个值，分别是WordA，WordB，WordC，WordD，如下所示：
- 初始化8个变量，例如64位类型的A ， B ， C ， D ， E ， F ， G ， H ，以存储给定字符串S的最终哈希值。
- 遍历数组Block []并执行以下步骤：
- 使用哈希函数通过逐个旋转一次，将A ， B ， C ， D ， E ， F ， G ， H的值更新为80次迭代。
- 现在，由以前的值的总和更新A，B，C，d，E，F，G，H的值A，B，C，d，E，F，G，H和A的新更新的值， B ， C ， D ， E ， F ， G ， H 。
- 完成上述步骤后，打印A ， B ， C ， D ， E ， F ， G ， H的十六进制值以获取给定字符串的哈希值。
下面是上述方法的实现：
C++14
// C++ program for the above approach
#include
using namespace std;
typedef unsigned long long int int64;
int64 Message[80];
// Stores the hexadecimal values for
// calculating hash values
const int64 Constants[80]
= { 0x428a2f98d728ae22, 0x7137449123ef65cd,
0xb5c0fbcfec4d3b2f, 0xe9b5dba58189dbbc,
0x3956c25bf348b538, 0x59f111f1b605d019,
0x923f82a4af194f9b, 0xab1c5ed5da6d8118,
0xd807aa98a3030242, 0x12835b0145706fbe,
0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
0x72be5d74f27b896f, 0x80deb1fe3b1696b1,
0x9bdc06a725c71235, 0xc19bf174cf692694,
0xe49b69c19ef14ad2, 0xefbe4786384f25e3,
0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65,
0x2de92c6f592b0275, 0x4a7484aa6ea6e483,
0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
0x983e5152ee66dfab, 0xa831c66d2db43210,
0xb00327c898fb213f, 0xbf597fc7beef0ee4,
0xc6e00bf33da88fc2, 0xd5a79147930aa725,
0x06ca6351e003826f, 0x142929670a0e6e70,
0x27b70a8546d22ffc, 0x2e1b21385c26c926,
0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
0x650a73548baf63de, 0x766a0abb3c77b2a8,
0x81c2c92e47edaee6, 0x92722c851482353b,
0xa2bfe8a14cf10364, 0xa81a664bbc423001,
0xc24b8b70d0f89791, 0xc76c51a30654be30,
0xd192e819d6ef5218, 0xd69906245565a910,
0xf40e35855771202a, 0x106aa07032bbd1b8,
0x19a4c116b8d2d0c8, 0x1e376c085141ab53,
0x2748774cdf8eeb99, 0x34b0bcb5e19b48a8,
0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb,
0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3,
0x748f82ee5defb2fc, 0x78a5636f43172f60,
0x84c87814a1f0ab72, 0x8cc702081a6439ec,
0x90befffa23631e28, 0xa4506cebde82bde9,
0xbef9a3f7b2c67915, 0xc67178f2e372532b,
0xca273eceea26619c, 0xd186b8c721c0c207,
0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178,
0x06f067aa72176fba, 0x0a637dc5a2c898a6,
0x113f9804bef90dae, 0x1b710b35131c471b,
0x28db77f523047d84, 0x32caab7b40c72493,
0x3c9ebe0a15c9bebc, 0x431d67c49c100d4c,
0x4cc5d4becb3e42b6, 0x597f299cfc657e2a,
0x5fcb6fab3ad6faec, 0x6c44198c4a475817 };
// Function to convert a binary string
// to hexa-decimal value
string gethex(string bin)
{
if (bin == "0000")
return "0";
if (bin == "0001")
return "1";
if (bin == "0010")
return "2";
if (bin == "0011")
return "3";
if (bin == "0100")
return "4";
if (bin == "0101")
return "5";
if (bin == "0110")
return "6";
if (bin == "0111")
return "7";
if (bin == "1000")
return "8";
if (bin == "1001")
return "9";
if (bin == "1010")
return "a";
if (bin == "1011")
return "b";
if (bin == "1100")
return "c";
if (bin == "1101")
return "d";
if (bin == "1110")
return "e";
if (bin == "1111")
return "f";
}
// Function to convert a decimal value
// to hexa decimal value
string decimaltohex(int64 deci)
{
// Stores the value as string
string EQBIN = bitset<64>(deci).to_string();
// Stores the equivalent hexa decimal
string hexstring = "";
string temp;
// Traverse the string EQBIN
for (unsigned int i = 0;
i < EQBIN.length(); i += 4) {
temp = EQBIN.substr(i, 4);
hexstring += gethex(temp);
}
// Return the hexstring
return hexstring;
}
// Function to convert a binary
// string to decimal value
int64 BintoDec(string bin)
{
int64 value = bitset<64>(bin)
.to_ullong();
return value;
}
// Function to right rotate x by n bits
int64 rotate_right(int64 x, int n)
{
return (x >> n) | (x << (64 - n));
}
// Function to right shift x by n bits
int64 shift_right(int64 x, int n)
{
return (x >> n);
}
// Function to divide the string
// into chunks
void seperator(string getBlock)
{
// Stores the size of chunks
int chunknum = 0;
// Traverse the string S
for (unsigned int i = 0;
i < getBlock.length();
i += 64, ++chunknum) {
// Update the Message[chunknum]
Message[chunknum]
= BintoDec(getBlock.substr(i, 64));
}
// Iterate over the range [16, 80]
for (int g = 16; g < 80; ++g) {
// Find the WordA
int64 WordA = rotate_right(Message[g - 2], 19)
^ rotate_right(Message[g - 2], 61)
^ shift_right(Message[g - 2], 6);
// Find the WordB
int64 WordB = Message[g - 7];
// Find the WordC
int64 WordC = rotate_right(Message[g - 15], 1)
^ rotate_right(Message[g - 15], 8)
^ shift_right(Message[g - 15], 7);
// Find the WordD
int64 WordD = Message[g - 16];
// Find the resultant code
int64 T = WordA + WordB + WordC + WordD;
// Return the resultant Hash Code
Message[g] = T;
}
}
// Function to find the major of a, b, c
int64 maj(int64 a, int64 b, int64 c)
{
return (a & b) ^ (b & c) ^ (c & a);
}
// Function to find the ch value of a,
// b, and c
int64 Ch(int64 e, int64 f, int64 g)
{
return (e & f) ^ (~e & g);
}
// Function to find the Bitwise XOR with
// the right rotate over 14, 18, and 41
int64 sigmaE(int64 e)
{
// Return the resultant value
return rotate_right(e, 14)
^ rotate_right(e, 18)
^ rotate_right(e, 41);
}
// Function to find the Bitwise XOR with
// the right rotate over 28, 34, and 39
int64 sigmaA(int64 a)
{
// Return the resultant value
return rotate_right(a, 28)
^ rotate_right(a, 34)
^ rotate_right(a, 39);
}
// Function to generate the hash code
void Func(int64 a, int64 b, int64 c,
int64& d, int64 e, int64 f,
int64 g, int64& h, int K)
{
// Find the Hash Code
int64 T1 = h + Ch(e, f, g) + sigmaE(e) + Message[K]
+ Constants[K];
int64 T2 = sigmaA(a) + maj(a, b, c);
d = d + T1;
h = T1 + T2;
}
// Function to convert the hash value
// of a given string
string SHA512(string myString)
{
// Stores the 8 blocks of size 64
int64 A = 0x6a09e667f3bcc908;
int64 B = 0xbb67ae8584caa73b;
int64 C = 0x3c6ef372fe94f82b;
int64 D = 0xa54ff53a5f1d36f1;
int64 E = 0x510e527fade682d1;
int64 F = 0x9b05688c2b3e6c1f;
int64 G = 0x1f83d9abfb41bd6b;
int64 H = 0x5be0cd19137e2179;
int64 AA, BB, CC, DD, EE, FF, GG, HH;
stringstream fixedstream;
// Traverse the string S
for (int i = 0;
i < myString.size(); ++i) {
// Add the charachter to stream
fixedstream << bitset<8>(myString[i]);
}
// Stores string of size 1024
string s1024;
// Stores the string in the
// fixedstream
s1024 = fixedstream.str();
// Stores the length of string
int orilen = s1024.length();
int tobeadded;
// Find moded string length
int modded = s1024.length() % 1024;
// If 1024-128 is greater than modded
if (1024 - modded >= 128) {
tobeadded = 1024 - modded;
}
// Else if 1024-128 is less than modded
else if (1024 - modded < 128) {
tobeadded = 2048 - modded;
}
// Append 1 to string
s1024 += "1";
// Append tobeadded-129 zeros
// in the string
for (int y = 0; y < tobeadded - 129; y++) {
s1024 += "0";
}
// Stores the binary reprsentation
// of string length
string lengthbits
= std::bitset<128>(orilen).to_string();
// Append the lengthbits to string
s1024 += lengthbits;
// Find the count of chunks of
// size 1024 each
int blocksnumber = s1024.length() / 1024;
// Stores the numbering of chunks
int chunknum = 0;
// Stores hash value of each blocks
string Blocks[blocksnumber];
// Traverse the string s1024
for (int i = 0; i < s1024.length();
i += 1024, ++chunknum) {
Blocks[chunknum] = s1024.substr(i, 1024);
}
// Traverse tha array Blocks[]
for (int letsgo = 0;
letsgo < blocksnumber;
++letsgo) {
// Divide the current string
// into 80 blocks size 16 each
seperator(Blocks[letsgo]);
AA = A;
BB = B;
CC = C;
DD = D;
EE = E;
FF = F;
GG = G;
HH = H;
int count = 0;
// Find hash values
for (int i = 0; i < 10; i++) {
// Find the Hash Values
Func(A, B, C, D, E, F, G, H, count);
count++;
Func(H, A, B, C, D, E, F, G, count);
count++;
Func(G, H, A, B, C, D, E, F, count);
count++;
Func(F, G, H, A, B, C, D, E, count);
count++;
Func(E, F, G, H, A, B, C, D, count);
count++;
Func(D, E, F, G, H, A, B, C, count);
count++;
Func(C, D, E, F, G, H, A, B, count);
count++;
Func(B, C, D, E, F, G, H, A, count);
count++;
}
// Update the value of A, B, C,
// D, E, F, G, H
A += AA;
B += BB;
C += CC;
D += DD;
E += EE;
F += FF;
G += GG;
H += HH;
}
stringstream output;
// Print the hexadecimal value of
// strings as the resultant SHA-512
output << decimaltohex(A);
output << decimaltohex(B);
output << decimaltohex(C);
output << decimaltohex(D);
output << decimaltohex(E);
output << decimaltohex(F);
output << decimaltohex(G);
output << decimaltohex(H);
// Return the string
return output.str();
}
// Driver Code
int main()
{
// Input
string S = "GeeksForGeeks";
// Function Call
cout << S << ": " << SHA512(S);
return 0;
} 输出：
GeeksForGeeks: 0acc10c4e0b38617f59e88e49215e2e894afaee5ec948c2af6f44039f03c9fe47a9210e01d5cd926c142bdc9179c2ad30f927a8faf69421ff60a5eaddcf8cb9c
时间复杂度： O(N)
辅助空间： O(1)
如果您希望与行业专家一起参加现场课程，请参阅《 Geeks现场课程》和《 Geeks现场课程美国》。