crypto.h File Reference

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Macros
#define	AES_BLOCK_SIZE   16
#define	SHA256_DIGEST_SIZE   32

Functions
int	encrypt_buffer (const char *in, size_t in_len, char **out, size_t *out_len)
	Encrypts a buffer using AES-128 in CBC mode.
int	decrypt_buffer (const char *in, size_t in_len, char **out, size_t *out_len)
	Decrypts a buffer using AES-128 in CBC mode.
int	hash_string (const char *input, u8 *digest)
	Hashes a string using SHA-256.
bool	are_hash_equals (const u8 *h1, const u8 *h2)
	Compares two SHA-256 hashes for equality.
void	hash_to_str (const u8 *digest, char *output)
	Converts a SHA-256 hash to a hexadecimal string.

Macro Definition Documentation

AES_BLOCK_SIZE

#define AES_BLOCK_SIZE   16

Definition at line 7 of file crypto.h.

SHA256_DIGEST_SIZE

#define SHA256_DIGEST_SIZE   32

Definition at line 9 of file crypto.h.

Function Documentation

are_hash_equals()

bool are_hash_equals	(	const u8 *	h1,
		const u8 *	h2
	)

Compares two SHA-256 hashes for equality.

Parameters

h1	First hash to compare.
h2	Second hash to compare.

Returns

true if the hashes are equal, false otherwise.

Definition at line 60 of file hash.c.

                                                 {
    if (!h1 || !h2)
        return false;
 
    return (memcmp(h1, h2, SHA256_DIGEST_SIZE) == 0) ? true : false;
}

decrypt_buffer()

int decrypt_buffer	(	const char *	in,
		size_t	in_len,
		char **	out,
		size_t *	out_len
	)

Decrypts a buffer using AES-128 in CBC mode.

Parameters

in	Input buffer to decrypt.
in_len	Length of the input buffer.
out	Pointer to the output buffer (allocated within the function).
out_len	Pointer to the length of the output buffer.

Returns

0 on success, negative error code on failure.

Definition at line 335 of file aes.c.

                                                                               {
    return _crypt_buffer(false, in, in_len, out, out_len);
}

encrypt_buffer()

int encrypt_buffer	(	const char *	in,
		size_t	in_len,
		char **	out,
		size_t *	out_len
	)

Encrypts a buffer using AES-128 in CBC mode.

Parameters

in	Input buffer to encrypt.
in_len	Length of the input buffer.
out	Pointer to the output buffer (allocated within the function).
out_len	Pointer to the length of the output buffer.

Returns

0 on success, negative error code on failure.

Definition at line 322 of file aes.c.

                                                                               {
    return _crypt_buffer(true, in, in_len, out, out_len);
}

hash_string()

int hash_string	(	const char *	input,
		u8 *	digest
	)

Hashes a string using SHA-256.

Parameters

input	Input string to hash.
digest	Output buffer for the hash (must be at least SHA256_DIGEST_SIZE bytes).

Returns

0 on success, negative error code on failure.

Definition at line 17 of file hash.c.

                                               {
    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;
}

hash_to_str()

void hash_to_str	(	const u8 *	digest,
		char *	output
	)

Converts a SHA-256 hash to a hexadecimal string.

Parameters

digest	Input hash to convert.
output	Output buffer for the hexadecimal string (must be at least SHA256_DIGEST_SIZE * 2 + 1 bytes).

Definition at line 74 of file hash.c.

                                                 {
    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
}