C++ sha2 functions


The four hash functions that make up the SHA-2 family are SHA-224, SHA-256, SHA-384, and SHA-512. Some of the uses for hashes include password verification, and digital signatures. Hash functions alone cannot prevent message tampering, but used properly with a key in an HMAC, can provide message authentication.

From a security standpoint, MD5 is broken and should never be used for digital signatures, and recently SHA-1 has been shown to be weaker than expected. SHA-2 is now recommended for all new applications. In addition, if working on US Government projects, remember that NIST has deprecated SHA-1 in since 2010, and that SHA-2 is considered approved for new projects.

SHA-2 hashes may used for password hashing, but you will need to implement a few extra things first. Make sure to use a random salt that is unique for every hash, which can be stored next to the hash. The purpose of the random salt is to prevent the attacker from being able to compute a single dictionary for the whole set, he instead has to compute a new dictionary for each hashed password. Apply multiple rounds of SHA-2, using a good work factor. For example, if your work factor is 10, then apply 2^10 rounds of your SHA2 algorithm, and then store the work factor, and your salt next to the hashed password. If you change your work factor later, you will still be able to verify passwords which used the old work factor.

main.cpp
#include <iostream>
#include "sha2.h"
 
using std::string;
using std::cout;
using std::endl;
 
int main(int argc, char *argv[])
{
    string input = "grape";
    string output1 = sha224(input);
    string output2 = sha256(input);
    string output3 = sha384(input);
    string output4 = sha512(input);
 
    cout << "sha224('"<< input << "'):" << output1 << endl;
    cout << "sha256('"<< input << "'):" << output2 << endl;
    cout << "sha384('"<< input << "'):" << output3 << endl;
    cout << "sha512('"<< input << "'):" << output4 << endl;
    return 0;
}

compile and run (linux):
g++ main.cpp sha2.cpp -i sha2_example && ./sha2_example

output:
sha224('grape'):571f3896fb694dc268b032d7940dabbfbcd7ee64c07f45c01c9e64db
sha256('grape'):0f78fcc486f5315418fbf095e71c0675ee07d318e5ac4d150050cd8e57966496
sha384('grape'):c2dafc387656342580027e2dbbbc2afcc77df4294b2542a983cf225735b88821302b9fa3c5948ba48b8dacd43da156d9
sha512('grape'):9375d1abdb644a01955bccad12e2f5c2bd8a3e226187e548d99c559a99461453b980123746753d07c169c22a5d9cc75cb158f0e8d8c0e713559775b5e1391fc4

sha2.h
#ifndef SHA2_H
#define SHA2_H
#include <string>
 
class SHA2
{
public:
    virtual void init() = 0;
    virtual void update(const unsigned char *message, unsigned int len) = 0;
    virtual void final(unsigned char *digest) = 0;
 
protected:
    typedef unsigned char uint8;
    typedef unsigned int uint32;
    typedef unsigned long long uint64;
};
 
class SHA256 : public SHA2
{
protected:
    const static uint32 sha256_k[];
    static const unsigned int SHA224_256_BLOCK_SIZE = (512/8);
public:
    void init();
    void update(const unsigned char *message, unsigned int len);
    void final(unsigned char *digest);
    static const unsigned int DIGEST_SIZE = ( 256 / 8);
protected:
    void transform(const unsigned char *message, unsigned int block_nb);
    unsigned int m_tot_len;
    unsigned int m_len;
    unsigned char m_block[2*SHA224_256_BLOCK_SIZE];
    uint32 m_h[8];
};
 
 
class SHA224 : public SHA256
{
public:
    void init();
    void update(const unsigned char *message, unsigned int len);
    void final(unsigned char *digest);
    static const unsigned int DIGEST_SIZE = ( 224 / 8);
};
 
 
class SHA512 : public SHA2
{
protected:
    const static uint64 sha512_k[];
    static const unsigned int SHA384_512_BLOCK_SIZE = (1024/8);
 
public:
    void init();
    void update(const unsigned char *message, unsigned int len);
    void final(unsigned char *digest);
    static const unsigned int DIGEST_SIZE = ( 512 / 8);
 
protected:
    void transform(const unsigned char *message, unsigned int block_nb);
    unsigned int m_tot_len;
    unsigned int m_len;
    unsigned char m_block[2 * SHA384_512_BLOCK_SIZE];
    uint64 m_h[8];
};
 
class SHA384 : public SHA512
{
public:
    void init();
    void update(const unsigned char *message, unsigned int len);
    void final(unsigned char *digest);
    static const unsigned int DIGEST_SIZE = ( 384 / 8);
};
 
std::string sha224(std::string input);
std::string sha256(std::string input);
std::string sha384(std::string input);
std::string sha512(std::string input);
 
#define SHA2_SHFR(x, n)    (x >> n)
#define SHA2_ROTR(x, n)   ((x >> n) | (x << ((sizeof(x) << 3) - n)))
#define SHA2_ROTL(x, n)   ((x << n) | (x >> ((sizeof(x) << 3) - n)))
#define SHA2_CH(x, y, z)  ((x & y) ^ (~x & z))
#define SHA2_MAJ(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
#define SHA256_F1(x) (SHA2_ROTR(x,  2) ^ SHA2_ROTR(x, 13) ^ SHA2_ROTR(x, 22))
#define SHA256_F2(x) (SHA2_ROTR(x,  6) ^ SHA2_ROTR(x, 11) ^ SHA2_ROTR(x, 25))
#define SHA256_F3(x) (SHA2_ROTR(x,  7) ^ SHA2_ROTR(x, 18) ^ SHA2_SHFR(x,  3))
#define SHA256_F4(x) (SHA2_ROTR(x, 17) ^ SHA2_ROTR(x, 19) ^ SHA2_SHFR(x, 10))
#define SHA512_F1(x) (SHA2_ROTR(x, 28) ^ SHA2_ROTR(x, 34) ^ SHA2_ROTR(x, 39))
#define SHA512_F2(x) (SHA2_ROTR(x, 14) ^ SHA2_ROTR(x, 18) ^ SHA2_ROTR(x, 41))
#define SHA512_F3(x) (SHA2_ROTR(x,  1) ^ SHA2_ROTR(x,  8) ^ SHA2_SHFR(x,  7))
#define SHA512_F4(x) (SHA2_ROTR(x, 19) ^ SHA2_ROTR(x, 61) ^ SHA2_SHFR(x,  6))
#define SHA2_UNPACK32(x, str)                 \
{                                             \
    *((str) + 3) = (uint8) ((x)      );       \
    *((str) + 2) = (uint8) ((x) >>  8);       \
    *((str) + 1) = (uint8) ((x) >> 16);       \
    *((str) + 0) = (uint8) ((x) >> 24);       \
}
#define SHA2_PACK32(str, x)                   \
{                                             \
    *(x) =   ((uint32) *((str) + 3)      )    \
           | ((uint32) *((str) + 2) <<  8)    \
           | ((uint32) *((str) + 1) << 16)    \
           | ((uint32) *((str) + 0) << 24);   \
}
#define SHA2_UNPACK64(x, str)                 \
{                                             \
    *((str) + 7) = (uint8) ((x)      );       \
    *((str) + 6) = (uint8) ((x) >>  8);       \
    *((str) + 5) = (uint8) ((x) >> 16);       \
    *((str) + 4) = (uint8) ((x) >> 24);       \
    *((str) + 3) = (uint8) ((x) >> 32);       \
    *((str) + 2) = (uint8) ((x) >> 40);       \
    *((str) + 1) = (uint8) ((x) >> 48);       \
    *((str) + 0) = (uint8) ((x) >> 56);       \
}
#define SHA2_PACK64(str, x)                   \
{                                             \
    *(x) =   ((uint64) *((str) + 7)      )    \
           | ((uint64) *((str) + 6) <<  8)    \
           | ((uint64) *((str) + 5) << 16)    \
           | ((uint64) *((str) + 4) << 24)    \
           | ((uint64) *((str) + 3) << 32)    \
           | ((uint64) *((str) + 2) << 40)    \
           | ((uint64) *((str) + 1) << 48)    \
           | ((uint64) *((str) + 0) << 56);   \
}
 
#endif

sha2.cpp
#include <cstring>
#include <fstream>
#include "sha2.h"
 
const unsigned int SHA256::sha256_k[64] = //UL = uint32
            {0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
             0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
             0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
             0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
             0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
             0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
             0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
             0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
             0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
             0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
             0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
             0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
             0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
             0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
             0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
             0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};
const unsigned long long SHA512::sha512_k[80] = //ULL = uint64
            {0x428a2f98d728ae22ULL, 0x7137449123ef65cdULL,
             0xb5c0fbcfec4d3b2fULL, 0xe9b5dba58189dbbcULL,
             0x3956c25bf348b538ULL, 0x59f111f1b605d019ULL,
             0x923f82a4af194f9bULL, 0xab1c5ed5da6d8118ULL,
             0xd807aa98a3030242ULL, 0x12835b0145706fbeULL,
             0x243185be4ee4b28cULL, 0x550c7dc3d5ffb4e2ULL,
             0x72be5d74f27b896fULL, 0x80deb1fe3b1696b1ULL,
             0x9bdc06a725c71235ULL, 0xc19bf174cf692694ULL,
             0xe49b69c19ef14ad2ULL, 0xefbe4786384f25e3ULL,
             0x0fc19dc68b8cd5b5ULL, 0x240ca1cc77ac9c65ULL,
             0x2de92c6f592b0275ULL, 0x4a7484aa6ea6e483ULL,
             0x5cb0a9dcbd41fbd4ULL, 0x76f988da831153b5ULL,
             0x983e5152ee66dfabULL, 0xa831c66d2db43210ULL,
             0xb00327c898fb213fULL, 0xbf597fc7beef0ee4ULL,
             0xc6e00bf33da88fc2ULL, 0xd5a79147930aa725ULL,
             0x06ca6351e003826fULL, 0x142929670a0e6e70ULL,
             0x27b70a8546d22ffcULL, 0x2e1b21385c26c926ULL,
             0x4d2c6dfc5ac42aedULL, 0x53380d139d95b3dfULL,
             0x650a73548baf63deULL, 0x766a0abb3c77b2a8ULL,
             0x81c2c92e47edaee6ULL, 0x92722c851482353bULL,
             0xa2bfe8a14cf10364ULL, 0xa81a664bbc423001ULL,
             0xc24b8b70d0f89791ULL, 0xc76c51a30654be30ULL,
             0xd192e819d6ef5218ULL, 0xd69906245565a910ULL,
             0xf40e35855771202aULL, 0x106aa07032bbd1b8ULL,
             0x19a4c116b8d2d0c8ULL, 0x1e376c085141ab53ULL,
             0x2748774cdf8eeb99ULL, 0x34b0bcb5e19b48a8ULL,
             0x391c0cb3c5c95a63ULL, 0x4ed8aa4ae3418acbULL,
             0x5b9cca4f7763e373ULL, 0x682e6ff3d6b2b8a3ULL,
             0x748f82ee5defb2fcULL, 0x78a5636f43172f60ULL,
             0x84c87814a1f0ab72ULL, 0x8cc702081a6439ecULL,
             0x90befffa23631e28ULL, 0xa4506cebde82bde9ULL,
             0xbef9a3f7b2c67915ULL, 0xc67178f2e372532bULL,
             0xca273eceea26619cULL, 0xd186b8c721c0c207ULL,
             0xeada7dd6cde0eb1eULL, 0xf57d4f7fee6ed178ULL,
             0x06f067aa72176fbaULL, 0x0a637dc5a2c898a6ULL,
             0x113f9804bef90daeULL, 0x1b710b35131c471bULL,
             0x28db77f523047d84ULL, 0x32caab7b40c72493ULL,
             0x3c9ebe0a15c9bebcULL, 0x431d67c49c100d4cULL,
             0x4cc5d4becb3e42b6ULL, 0x597f299cfc657e2aULL,
             0x5fcb6fab3ad6faecULL, 0x6c44198c4a475817ULL};
 
void SHA224::init()
{
    m_h[0]=0xc1059ed8;
    m_h[1]=0x367cd507;
    m_h[2]=0x3070dd17;
    m_h[3]=0xf70e5939;
    m_h[4]=0xffc00b31;
    m_h[5]=0x68581511;
    m_h[6]=0x64f98fa7;
    m_h[7]=0xbefa4fa4;
    m_len = 0;
    m_tot_len = 0;
}
 
void SHA224::update(const unsigned char *message, unsigned int len)
{
    unsigned int block_nb;
    unsigned int new_len, rem_len, tmp_len;
    const unsigned char *shifted_message;
    tmp_len = SHA224_256_BLOCK_SIZE - m_len;
    rem_len = len < tmp_len ? len : tmp_len;
    memcpy(&m_block[m_len], message, rem_len);
    if (m_len + len < SHA224_256_BLOCK_SIZE) {
        m_len += len;
        return;
    }
    new_len = len - rem_len;
    block_nb = new_len / SHA224_256_BLOCK_SIZE;
    shifted_message = message + rem_len;
    transform(m_block, 1);
    transform(shifted_message, block_nb);
    rem_len = new_len % SHA224_256_BLOCK_SIZE;
    memcpy(m_block, &shifted_message[block_nb << 6], rem_len);
    m_len = rem_len;
    m_tot_len += (block_nb + 1) << 6;
}
 
void SHA224::final(unsigned char *digest)
{
    unsigned int block_nb;
    unsigned int pm_len;
    unsigned int len_b;
    int i;
    block_nb = (1 + ((SHA224_256_BLOCK_SIZE - 9)
                     < (m_len % SHA224_256_BLOCK_SIZE)));
    len_b = (m_tot_len + m_len) << 3;
    pm_len = block_nb << 6;
    memset(m_block + m_len, 0, pm_len - m_len);
    m_block[m_len] = 0x80;
    SHA2_UNPACK32(len_b, m_block + pm_len - 4);
    transform(m_block, block_nb);
    for (i = 0 ; i < 7; i++) {
        SHA2_UNPACK32(m_h[i], &digest[i << 2]);
    }
}
 
void SHA256::transform(const unsigned char *message, unsigned int block_nb)
{
    uint32 w[64];
    uint32 wv[8];
    uint32 t1, t2;
    const unsigned char *sub_block;
    int i;
    int j;
    for (i = 0; i < (int) block_nb; i++) {
        sub_block = message + (i << 6);
        for (j = 0; j < 16; j++) {
            SHA2_PACK32(&sub_block[j << 2], &w[j]);
        }
        for (j = 16; j < 64; j++) {
            w[j] =  SHA256_F4(w[j -  2]) + w[j -  7] + SHA256_F3(w[j - 15]) + w[j - 16];
        }
        for (j = 0; j < 8; j++) {
            wv[j] = m_h[j];
        }
        for (j = 0; j < 64; j++) {
            t1 = wv[7] + SHA256_F2(wv[4]) + SHA2_CH(wv[4], wv[5], wv[6])
                + sha256_k[j] + w[j];
            t2 = SHA256_F1(wv[0]) + SHA2_MAJ(wv[0], wv[1], wv[2]);
            wv[7] = wv[6];
            wv[6] = wv[5];
            wv[5] = wv[4];
            wv[4] = wv[3] + t1;
            wv[3] = wv[2];
            wv[2] = wv[1];
            wv[1] = wv[0];
            wv[0] = t1 + t2;
        }
        for (j = 0; j < 8; j++) {
            m_h[j] += wv[j];
        }
    }
}
 
void SHA256::init()
{
    m_h[0] = 0x6a09e667;
    m_h[1] = 0xbb67ae85;
    m_h[2] = 0x3c6ef372;
    m_h[3] = 0xa54ff53a;
    m_h[4] = 0x510e527f;
    m_h[5] = 0x9b05688c;
    m_h[6] = 0x1f83d9ab;
    m_h[7] = 0x5be0cd19;
    m_len = 0;
    m_tot_len = 0;
}
 
void SHA256::update(const unsigned char *message, unsigned int len)
{
    unsigned int block_nb;
    unsigned int new_len, rem_len, tmp_len;
    const unsigned char *shifted_message;
    tmp_len = SHA224_256_BLOCK_SIZE - m_len;
    rem_len = len < tmp_len ? len : tmp_len;
    memcpy(&m_block[m_len], message, rem_len);
    if (m_len + len < SHA224_256_BLOCK_SIZE) {
        m_len += len;
        return;
    }
    new_len = len - rem_len;
    block_nb = new_len / SHA224_256_BLOCK_SIZE;
    shifted_message = message + rem_len;
    transform(m_block, 1);
    transform(shifted_message, block_nb);
    rem_len = new_len % SHA224_256_BLOCK_SIZE;
    memcpy(m_block, &shifted_message[block_nb << 6], rem_len);
    m_len = rem_len;
    m_tot_len += (block_nb + 1) << 6;
}
 
void SHA256::final(unsigned char *digest)
{
    unsigned int block_nb;
    unsigned int pm_len;
    unsigned int len_b;
    int i;
    block_nb = (1 + ((SHA224_256_BLOCK_SIZE - 9)
                     < (m_len % SHA224_256_BLOCK_SIZE)));
    len_b = (m_tot_len + m_len) << 3;
    pm_len = block_nb << 6;
    memset(m_block + m_len, 0, pm_len - m_len);
    m_block[m_len] = 0x80;
    SHA2_UNPACK32(len_b, m_block + pm_len - 4);
    transform(m_block, block_nb);
    for (i = 0 ; i < 8; i++) {
        SHA2_UNPACK32(m_h[i], &digest[i << 2]);
    }
}
 
void SHA384::init()
{
    m_h[0] = 0xcbbb9d5dc1059ed8ULL;
    m_h[1] = 0x629a292a367cd507ULL;
    m_h[2] = 0x9159015a3070dd17ULL;
    m_h[3] = 0x152fecd8f70e5939ULL;
    m_h[4] = 0x67332667ffc00b31ULL;
    m_h[5] = 0x8eb44a8768581511ULL;
    m_h[6] = 0xdb0c2e0d64f98fa7ULL;
    m_h[7] = 0x47b5481dbefa4fa4ULL;
    m_len = 0;
    m_tot_len = 0;
}
 
void SHA384::update(const unsigned char *message, unsigned int len)
{
    unsigned int block_nb;
    unsigned int new_len, rem_len, tmp_len;
    const unsigned char *shifted_message;
    tmp_len = SHA384_512_BLOCK_SIZE - m_len;
    rem_len = len < tmp_len ? len : tmp_len;
    memcpy(&m_block[m_len], message, rem_len);
    if (m_len + len < SHA384_512_BLOCK_SIZE) {
        m_len += len;
        return;
    }
    new_len = len - rem_len;
    block_nb = new_len / SHA384_512_BLOCK_SIZE;
    shifted_message = message + rem_len;
    transform(m_block, 1);
    transform(shifted_message, block_nb);
    rem_len = new_len % SHA384_512_BLOCK_SIZE;
    memcpy(m_block, &shifted_message[block_nb << 7], rem_len);
    m_len = rem_len;
    m_tot_len += (block_nb + 1) << 7;
}
 
void SHA384::final(unsigned char *digest)
{
    unsigned int block_nb;
    unsigned int pm_len;
    unsigned int len_b;
    int i;
    block_nb = (1 + ((SHA384_512_BLOCK_SIZE - 17)
                     < (m_len % SHA384_512_BLOCK_SIZE)));
    len_b = (m_tot_len + m_len) << 3;
    pm_len = block_nb << 7;
    memset(m_block + m_len, 0, pm_len - m_len);
    m_block[m_len] = 0x80;
    SHA2_UNPACK32(len_b, m_block + pm_len - 4);
    transform(m_block, block_nb);
    for (i = 0 ; i < 6; i++) {
        SHA2_UNPACK64(m_h[i], &digest[i << 3]);
    }
}
 
void SHA512::transform(const unsigned char *message, unsigned int block_nb)
{
    uint64 w[80];
    uint64 wv[8];
    uint64 t1, t2;
    const unsigned char *sub_block;
    int i, j;
    for (i = 0; i < (int) block_nb; i++) {
        sub_block = message + (i << 7);
        for (j = 0; j < 16; j++) {
            SHA2_PACK64(&sub_block[j << 3], &w[j]);
        }
        for (j = 16; j < 80; j++) {
            w[j] =  SHA512_F4(w[j -  2]) + w[j -  7] + SHA512_F3(w[j - 15]) + w[j - 16];
        }
        for (j = 0; j < 8; j++) {
            wv[j] = m_h[j];
        }
        for (j = 0; j < 80; j++) {
            t1 = wv[7] + SHA512_F2(wv[4]) + SHA2_CH(wv[4], wv[5], wv[6])
                + sha512_k[j] + w[j];
            t2 = SHA512_F1(wv[0]) + SHA2_MAJ(wv[0], wv[1], wv[2]);
            wv[7] = wv[6];
            wv[6] = wv[5];
            wv[5] = wv[4];
            wv[4] = wv[3] + t1;
            wv[3] = wv[2];
            wv[2] = wv[1];
            wv[1] = wv[0];
            wv[0] = t1 + t2;
        }
        for (j = 0; j < 8; j++) {
            m_h[j] += wv[j];
        }
 
    }
}
 
void SHA512::init()
{
    m_h[0] = 0x6a09e667f3bcc908ULL;
    m_h[1] = 0xbb67ae8584caa73bULL;
    m_h[2] = 0x3c6ef372fe94f82bULL;
    m_h[3] = 0xa54ff53a5f1d36f1ULL;
    m_h[4] = 0x510e527fade682d1ULL;
    m_h[5] = 0x9b05688c2b3e6c1fULL;
    m_h[6] = 0x1f83d9abfb41bd6bULL; 
    m_h[7] = 0x5be0cd19137e2179ULL;
    m_len = 0;
    m_tot_len = 0;
}
 
void SHA512::update(const unsigned char *message, unsigned int len)
{
    unsigned int block_nb;
    unsigned int new_len, rem_len, tmp_len;
    const unsigned char *shifted_message;
    tmp_len = SHA384_512_BLOCK_SIZE - m_len;
    rem_len = len < tmp_len ? len : tmp_len;
    memcpy(&m_block[m_len], message, rem_len);
    if (m_len + len < SHA384_512_BLOCK_SIZE) {
        m_len += len;
        return;
    }
    new_len = len - rem_len;
    block_nb = new_len / SHA384_512_BLOCK_SIZE;
    shifted_message = message + rem_len;
    transform(m_block, 1);
    transform(shifted_message, block_nb);
    rem_len = new_len % SHA384_512_BLOCK_SIZE;
    memcpy(m_block, &shifted_message[block_nb << 7], rem_len);
    m_len = rem_len;
    m_tot_len += (block_nb + 1) << 7;
}
 
void SHA512::final(unsigned char *digest)
{
    unsigned int block_nb;
    unsigned int pm_len;
    unsigned int len_b;
    int i;
    block_nb = 1 + ((SHA384_512_BLOCK_SIZE - 17)
                     < (m_len % SHA384_512_BLOCK_SIZE));
    len_b = (m_tot_len + m_len) << 3;
    pm_len = block_nb << 7;
    memset(m_block + m_len, 0, pm_len - m_len);
    m_block[m_len] = 0x80;
    SHA2_UNPACK32(len_b, m_block + pm_len - 4);
    transform(m_block, block_nb);
    for (i = 0 ; i < 8; i++) {
        SHA2_UNPACK64(m_h[i], &digest[i << 3]);
    }
}
 
std::string sha224(std::string input)
{
    unsigned char digest[SHA224::DIGEST_SIZE];
    memset(digest,0,SHA224::DIGEST_SIZE);
    SHA224 ctx = SHA224();
    ctx.init();
    ctx.update((unsigned char*)input.c_str(), input.length());
    ctx.final(digest);
 
    char buf[2*SHA224::DIGEST_SIZE+1];
    buf[2*SHA224::DIGEST_SIZE] = 0;
    for (int i = 0; i < SHA224::DIGEST_SIZE; i++)
        sprintf(buf+i*2, "%02x", digest[i]);
    return std::string(buf);
}
 
std::string sha256(std::string input)
{
    unsigned char digest[SHA256::DIGEST_SIZE];
    memset(digest,0,SHA256::DIGEST_SIZE);
 
    SHA256 ctx = SHA256();
    ctx.init();
    ctx.update( (unsigned char*)input.c_str(), input.length());
    ctx.final(digest);
 
    char buf[2*SHA256::DIGEST_SIZE+1];
    buf[2*SHA256::DIGEST_SIZE] = 0;
    for (int i = 0; i < SHA256::DIGEST_SIZE; i++)
        sprintf(buf+i*2, "%02x", digest[i]);
    return std::string(buf);
}
 
std::string sha384(std::string input)
{
    unsigned char digest[SHA384::DIGEST_SIZE];
    memset(digest,0,SHA384::DIGEST_SIZE);
    SHA384 ctx = SHA384();
    ctx.init();
    ctx.update((unsigned char*)input.c_str(), input.length());
    ctx.final(digest);
 
    char buf[2*SHA384::DIGEST_SIZE+1];
    buf[2*SHA384::DIGEST_SIZE] = 0;
    for (int i = 0; i < SHA384::DIGEST_SIZE; i++)
        sprintf(buf+i*2, "%02x", digest[i]);
    return std::string(buf);
}
 
std::string sha512(std::string input)
{
    unsigned char digest[SHA512::DIGEST_SIZE];
    memset(digest,0,SHA512::DIGEST_SIZE);
    SHA512 ctx = SHA512();
    ctx.init();
    ctx.update((unsigned char*)input.c_str(), input.length());
    ctx.final(digest);
 
    char buf[2*SHA512::DIGEST_SIZE+1];
    buf[2*SHA512::DIGEST_SIZE] = 0;
    for (int i = 0; i < SHA512::DIGEST_SIZE; i++)
        sprintf(buf+i*2, "%02x", digest[i]);
    return std::string(buf);
}

LICENSE.txt
/*
 * Updated to C++, zedwood.com 2012
 * Based on Olivier Gay's version
 * See Modified BSD License below: 
 *
 * FIPS 180-2 SHA-224/256/384/512 implementation
 * Issue date:  04/30/2005
 * http://www.ouah.org/ogay/sha2/
 *
 * Copyright (C) 2005, 2007 Olivier Gay <olivier.gay@a3.epfl.ch>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */