hash.c

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#include <crypto/hash.h>
#include <linux/crypto.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/string.h>
 
#include "crypto.h"
 
int hash_string(const char *input, u8 *digest) {
    struct crypto_shash *tfm; // Hash transformation handle
    struct shash_desc *shash; // Hash descriptor
    char *desc_buffer;        // Buffer for hash descriptor
    int desc_size, ret;
 
    if (!input || !digest)
        return -EINVAL;
 
    // Allocate hash transformation for SHA-256
    tfm = crypto_alloc_shash("sha256", 0, 0);
    if (IS_ERR(tfm)) {
        pr_err("Erreur allocation tfm SHA-256\n");
        return PTR_ERR(tfm);
    }
 
    // Allocate memory for hash descriptor
    desc_size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm);
    desc_buffer = kmalloc(desc_size, GFP_KERNEL);
    if (!desc_buffer) {
        crypto_free_shash(tfm);
        return -ENOMEM;
    }
 
    shash = (struct shash_desc *)desc_buffer;
    shash->tfm = tfm;
 
    // Compute the hash
    ret = crypto_shash_digest(shash, input, strlen(input), digest);
 
    kfree(desc_buffer);     // Free descriptor buffer
    crypto_free_shash(tfm); // Free hash transformation
 
    return ret;
}
 
bool are_hash_equals(const u8 *h1, const u8 *h2) {
    if (!h1 || !h2)
        return false;
 
    return (memcmp(h1, h2, SHA256_DIGEST_SIZE) == 0) ? true : false;
}
 
void hash_to_str(const u8 *digest, char *output) {
    int i;
 
    if (!digest || !output) {
        pr_err("hash_to_str: digest or output NULL\n");
        return;
    }
 
    // Convert each byte of the hash to a 2-character hexadecimal representation
    for (i = 0; i < SHA256_DIGEST_SIZE; i++)
        sprintf(output + (i * 2), "%02x", digest[i]);
    output[SHA256_DIGEST_SIZE * 2] = '\0'; // Null-terminate the string
}