sha1.c-Dateireferenz

#include "eyefi.h"
#include <string.h>

Include-Abhängigkeitsdiagramm für sha1.c:

gehe zum Quellcode dieser Datei

Datenstrukturen
struct	SHA1Context

Makrodefinitionen
#define	SHA1_MAC_LEN   20
#define	MD5_MAC_LEN   16
#define	SHA1HANDSOFF
#define	rol(value, bits)   (((value) << (bits)) | ((value) >> (32 - (bits))))
#define	blk0(i)
#define	blk(i)
#define	R0(v, w, x, y, z, i)
#define	R1(v, w, x, y, z, i)
#define	R2(v, w, x, y, z, i)   z += (w ^ x ^ y) + blk(i) + 0x6ED9EBA1 + rol(v, 5); w = rol(w, 30);
#define	R3(v, w, x, y, z, i)
#define	R4(v, w, x, y, z, i)

Typdefinitionen
typedef struct SHA1Context	SHA1_CTX

Funktionen
void	sha1_vector (size_t num_elem, const u8 *addr[], const size_t *len, u8 *mac)
void	hmac_sha1_vector (const u8 *key, size_t key_len, size_t num_elem, const u8 *addr[], const size_t *len, u8 *mac)
void	hmac_sha1 (const u8 *key, size_t key_len, const u8 *data, size_t data_len, u8 *mac)
void	sha1_prf (const u8 *key, size_t key_len, const char *label, const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
void	sha1_t_prf (const u8 *key, size_t key_len, const char *label, const u8 *seed, size_t seed_len, u8 *buf, size_t buf_len)
int	tls_prf (const u8 *secret, size_t secret_len, const char *label, const u8 *seed, size_t seed_len, u8 *out, size_t outlen)
static void	pbkdf2_sha1_f (const char *passphrase, const char *ssid, size_t ssid_len, int iterations, unsigned int count, u8 *digest)
void	pbkdf2_sha1 (const char *passphrase, const char *ssid, size_t ssid_len, int iterations, u8 *buf, size_t buflen)
static void	SHA1Init (struct SHA1Context *context)
static void	SHA1Update (struct SHA1Context *context, const void *data, u32 len)
static void	SHA1Final (unsigned char digest[20], struct SHA1Context *context)
static void	SHA1Transform (u32 state[5], const unsigned char buffer[64])
int	fips186_2_prf (const u8 *seed, size_t seed_len, u8 *x, size_t xlen)

Makro-Dokumentation

#define blk

(

i)

Wert:

(block->l[i & 15] = rol(block->l[(i + 13) & 15] ^ \
    block->l[(i + 8) & 15] ^ block->l[(i + 2) & 15] ^ block->l[i & 15], 1))

Definiert in Zeile 553 der Datei sha1.c.

#define blk0

(

i)

Wert:

(block->l[i] = (rol(block->l[i], 24) & 0xFF00FF00) | \
    (rol(block->l[i], 8) & 0x00FF00FF))

Definiert in Zeile 548 der Datei sha1.c.

#define MD5_MAC_LEN   16

Definiert in Zeile 24 der Datei sha1.c.

#define R0	(		v,
			w,
			x,
			y,
			z,
			i
	)

Wert:

z += ((w & (x ^ y)) ^ y) + blk0(i) + 0x5A827999 + rol(v, 5); \
    w = rol(w, 30);

Definiert in Zeile 557 der Datei sha1.c.

#define R1	(		v,
			w,
			x,
			y,
			z,
			i
	)

Wert:

z += ((w & (x ^ y)) ^ y) + blk(i) + 0x5A827999 + rol(v, 5); \
    w = rol(w, 30);

Definiert in Zeile 560 der Datei sha1.c.

#define R2	(		v,
			w,
			x,
			y,
			z,
			i
	)		z += (w ^ x ^ y) + blk(i) + 0x6ED9EBA1 + rol(v, 5); w = rol(w, 30);

Definiert in Zeile 563 der Datei sha1.c.

#define R3	(		v,
			w,
			x,
			y,
			z,
			i
	)

Wert:

z += (((w | x) & y) | (w & x)) + blk(i) + 0x8F1BBCDC + rol(v, 5); \
    w = rol(w, 30);

Definiert in Zeile 565 der Datei sha1.c.

#define R4	(		v,
			w,
			x,
			y,
			z,
			i
	)

Wert:

z += (w ^ x ^ y) + blk(i) + 0xCA62C1D6 + rol(v, 5); \
    w=rol(w, 30);

Definiert in Zeile 568 der Datei sha1.c.

#define rol	(		value,
			bits
	)		(((value) << (bits)) | ((value) >> (32 - (bits))))

Definiert in Zeile 543 der Datei sha1.c.

#define SHA1_MAC_LEN   20

Definiert in Zeile 21 der Datei sha1.c.

#define SHA1HANDSOFF

Definiert in Zeile 541 der Datei sha1.c.

Dokumentation der benutzerdefinierten Typen

typedef struct SHA1Context SHA1_CTX

Definiert in Zeile 378 der Datei sha1.c.

Dokumentation der Funktionen

int fips186_2_prf	(	const u8 *	seed,
		size_t	seed_len,
		u8 *	x,
		size_t	xlen
	)

Definiert in Zeile 407 der Datei sha1.c.

{
    u8 xkey[64];
    u32 t[5], _t[5];
    int i, j, m, k;
    u8 *xpos = x;
    u32 carry;

    if (seed_len > sizeof(xkey))
        seed_len = sizeof(xkey);

    /* FIPS 186-2 + change notice 1 */

    memcpy(xkey, seed, seed_len);
    memset(xkey + seed_len, 0, 64 - seed_len);
    t[0] = 0x67452301;
    t[1] = 0xEFCDAB89;
    t[2] = 0x98BADCFE;
    t[3] = 0x10325476;
    t[4] = 0xC3D2E1F0;

    m = xlen / 40;
    for (j = 0; j < m; j++) {
        /* XSEED_j = 0 */
        for (i = 0; i < 2; i++) {
            /* XVAL = (XKEY + XSEED_j) mod 2^b */

            /* w_i = G(t, XVAL) */
            memcpy(_t, t, 20);
            SHA1Transform(_t, xkey);
            _t[0] = host_to_be32(_t[0]);
            _t[1] = host_to_be32(_t[1]);
            _t[2] = host_to_be32(_t[2]);
            _t[3] = host_to_be32(_t[3]);
            _t[4] = host_to_be32(_t[4]);
            memcpy(xpos, _t, 20);

            /* XKEY = (1 + XKEY + w_i) mod 2^b */
            carry = 1;
            for (k = 19; k >= 0; k--) {
                carry += xkey[k] + xpos[k];
                xkey[k] = carry & 0xff;
                carry >>= 8;
            }

            xpos += SHA1_MAC_LEN;
        }
        /* x_j = w_0|w_1 */
    }

    return 0;
}

void hmac_sha1	(	const u8 *	key,
		size_t	key_len,
		const u8 *	data,
		size_t	data_len,
		u8 *	mac
	)

hmac_sha1 - HMAC-SHA1 over data buffer (RFC 2104) : Key for HMAC operations : Length of the key in bytes : Pointers to the data area : Length of the data area : Buffer for the hash (20 bytes)

Definiert in Zeile 106 der Datei sha1.c.

{
    hmac_sha1_vector(key, key_len, 1, &data, &data_len, mac);
}

void hmac_sha1_vector	(	const u8 *	key,
		size_t	key_len,
		size_t	num_elem,
		const u8 *	addr[],
		const size_t *	len,
		u8 *	mac
	)

hmac_sha1_vector - HMAC-SHA1 over data vector (RFC 2104) : Key for HMAC operations : Length of the key in bytes : Number of elements in the data vector : Pointers to the data areas : Lengths of the data blocks : Buffer for the hash (20 bytes)

Definiert in Zeile 35 der Datei sha1.c.

{
    unsigned char k_pad[64]; /* padding - key XORd with ipad/opad */
    unsigned char tk[20];
    const u8 *_addr[6];
    size_t _len[6], i;

    if (num_elem > 5) {
        /*
         * Fixed limit on the number of fragments to avoid having to
         * allocate memory (which could fail).
         */
        return;
    }

        /* if key is longer than 64 bytes reset it to key = SHA1(key) */
        if (key_len > 64) {
        sha1_vector(1, &key, &key_len, tk);
        key = tk;
        key_len = 20;
        }

    /* the HMAC_SHA1 transform looks like:
     *
     * SHA1(K XOR opad, SHA1(K XOR ipad, text))
     *
     * where K is an n byte key
     * ipad is the byte 0x36 repeated 64 times
     * opad is the byte 0x5c repeated 64 times
     * and text is the data being protected */

    /* start out by storing key in ipad */
    memset(k_pad, 0, sizeof(k_pad));
    memcpy(k_pad, key, key_len);
    /* XOR key with ipad values */
    for (i = 0; i < 64; i++)
        k_pad[i] ^= 0x36;

    /* perform inner SHA1 */
    _addr[0] = k_pad;
    _len[0] = 64;
    for (i = 0; i < num_elem; i++) {
        _addr[i + 1] = addr[i];
        _len[i + 1] = len[i];
    }
    sha1_vector(1 + num_elem, _addr, _len, mac);

    memset(k_pad, 0, sizeof(k_pad));
    memcpy(k_pad, key, key_len);
    /* XOR key with opad values */
    for (i = 0; i < 64; i++)
        k_pad[i] ^= 0x5c;

    /* perform outer SHA1 */
    _addr[0] = k_pad;
    _len[0] = 64;
    _addr[1] = mac;
    _len[1] = SHA1_MAC_LEN;
    sha1_vector(2, _addr, _len, mac);
}

void pbkdf2_sha1	(	const char *	passphrase,
		const char *	ssid,
		size_t	ssid_len,
		int	iterations,
		u8 *	buf,
		size_t	buflen
	)

pbkdf2_sha1 - SHA1-based key derivation function (PBKDF2) for IEEE 802.11i : ASCII passphrase : SSID : SSID length in bytes : Number of iterations to run : Buffer for the generated key : Length of the buffer in bytes

This function is used to derive PSK for WPA-PSK. For this protocol, iterations is set to 4096 and buflen to 32. This function is described in IEEE Std 802.11-2004, Clause H.4. The main construction is from PKCS#5 v2.0.

Definiert in Zeile 352 der Datei sha1.c.

{
    unsigned int count = 0;
    unsigned char *pos = buf;
    size_t left = buflen, plen;
    unsigned char digest[SHA1_MAC_LEN];

    while (left > 0) {
        count++;
        pbkdf2_sha1_f(passphrase, ssid, ssid_len, iterations, count,
                  digest);
        plen = left > SHA1_MAC_LEN ? SHA1_MAC_LEN : left;
        memcpy(pos, digest, plen);
        pos += plen;
        left -= plen;
    }
}

static void pbkdf2_sha1_f ( const char *  passphrase, const char *  ssid, size_t  ssid_len, int  iterations, unsigned int  count, u8 *  digest  )

static

Definiert in Zeile 300 der Datei sha1.c.

{
    unsigned char tmp[SHA1_MAC_LEN], tmp2[SHA1_MAC_LEN];
    int i, j;
    unsigned char count_buf[4];
    const u8 *addr[2];
    size_t len[2];
    size_t passphrase_len = strlen(passphrase);

    addr[0] = (u8 *) ssid;
    len[0] = ssid_len;
    addr[1] = count_buf;
    len[1] = 4;

    /* F(P, S, c, i) = U1 xor U2 xor ... Uc
     * U1 = PRF(P, S || i)
     * U2 = PRF(P, U1)
     * Uc = PRF(P, Uc-1)
     */

    count_buf[0] = (count >> 24) & 0xff;
    count_buf[1] = (count >> 16) & 0xff;
    count_buf[2] = (count >> 8) & 0xff;
    count_buf[3] = count & 0xff;
    hmac_sha1_vector((u8 *) passphrase, passphrase_len, 2, addr, len, tmp);
    memcpy(digest, tmp, SHA1_MAC_LEN);

    for (i = 1; i < iterations; i++) {
        hmac_sha1((u8 *) passphrase, passphrase_len, tmp, SHA1_MAC_LEN,
              tmp2);
        memcpy(tmp, tmp2, SHA1_MAC_LEN);
        for (j = 0; j < SHA1_MAC_LEN; j++)
            digest[j] ^= tmp2[j];
    }
}

void sha1_prf	(	const u8 *	key,
		size_t	key_len,
		const char *	label,
		const u8 *	data,
		size_t	data_len,
		u8 *	buf,
		size_t	buf_len
	)

sha1_prf - SHA1-based Pseudo-Random Function (PRF) (IEEE 802.11i, 8.5.1.1) : Key for PRF : Length of the key in bytes : A unique label for each purpose of the PRF : Extra data to bind into the key : Length of the data : Buffer for the generated pseudo-random key : Number of bytes of key to generate

This function is used to derive new, cryptographically separate keys from a given key (e.g., PMK in IEEE 802.11i).

Definiert in Zeile 126 der Datei sha1.c.

{
    u8 zero = 0, counter = 0;
    size_t pos, plen;
    u8 hash[SHA1_MAC_LEN];
    size_t label_len = strlen(label);
    const unsigned char *addr[4];
    size_t len[4];

    addr[0] = (u8 *) label;
    len[0] = label_len;
    addr[1] = &zero;
    len[1] = 1;
    addr[2] = data;
    len[2] = data_len;
    addr[3] = &counter;
    len[3] = 1;

    pos = 0;
    while (pos < buf_len) {
        plen = buf_len - pos;
        if (plen >= SHA1_MAC_LEN) {
            hmac_sha1_vector(key, key_len, 4, addr, len,
                     &buf[pos]);
            pos += SHA1_MAC_LEN;
        } else {
            hmac_sha1_vector(key, key_len, 4, addr, len,
                     hash);
            memcpy(&buf[pos], hash, plen);
            break;
        }
        counter++;
    }
}

void sha1_t_prf	(	const u8 *	key,
		size_t	key_len,
		const char *	label,
		const u8 *	seed,
		size_t	seed_len,
		u8 *	buf,
		size_t	buf_len
	)

sha1_t_prf - EAP-FAST Pseudo-Random Function (T-PRF) : Key for PRF : Length of the key in bytes : A unique label for each purpose of the PRF : Seed value to bind into the key : Length of the seed : Buffer for the generated pseudo-random key : Number of bytes of key to generate

This function is used to derive new, cryptographically separate keys from a given key for EAP-FAST. T-PRF is defined in draft-cam-winget-eap-fast-02.txt, Appendix B.

Definiert in Zeile 177 der Datei sha1.c.

{
    unsigned char counter = 0;
    size_t pos, plen;
    u8 hash[SHA1_MAC_LEN];
    size_t label_len = strlen(label);
    u8 output_len[2];
    const unsigned char *addr[5];
    size_t len[5];

    addr[0] = hash;
    len[0] = 0;
    addr[1] = (unsigned char *) label;
    len[1] = label_len + 1;
    addr[2] = seed;
    len[2] = seed_len;
    addr[3] = output_len;
    len[3] = 2;
    addr[4] = &counter;
    len[4] = 1;

    output_len[0] = (buf_len >> 8) & 0xff;
    output_len[1] = buf_len & 0xff;
    pos = 0;
    while (pos < buf_len) {
        counter++;
        plen = buf_len - pos;
        hmac_sha1_vector(key, key_len, 5, addr, len, hash);
        if (plen >= SHA1_MAC_LEN) {
            memcpy(&buf[pos], hash, SHA1_MAC_LEN);
            pos += SHA1_MAC_LEN;
        } else {
            memcpy(&buf[pos], hash, plen);
            break;
        }
        len[0] = SHA1_MAC_LEN;
    }
}

void sha1_vector	(	size_t	num_elem,
		const u8 *	addr[],
		const size_t *	len,
		u8 *	mac
	)

sha1_vector - SHA-1 hash for data vector : Number of elements in the data vector : Pointers to the data areas : Lengths of the data blocks : Buffer for the hash

Definiert in Zeile 394 der Datei sha1.c.

{
    SHA1_CTX ctx;
    size_t i;

    SHA1Init(&ctx);
    for (i = 0; i < num_elem; i++)
        SHA1Update(&ctx, addr[i], len[i]);
    SHA1Final(mac, &ctx);
}

void SHA1Final ( unsigned char  digest[20], struct SHA1Context *  context  )

static

Definiert in Zeile 691 der Datei sha1.c.

{
    u32 i;
    unsigned char finalcount[8];

    for (i = 0; i < 8; i++) {
        finalcount[i] = (unsigned char)
            ((context->count[(i >= 4 ? 0 : 1)] >>
              ((3-(i & 3)) * 8) ) & 255);  /* Endian independent */
    }
    SHA1Update(context, (unsigned char *) "\200", 1);
    while ((context->count[0] & 504) != 448) {
        SHA1Update(context, (unsigned char *) "\0", 1);
    }
    SHA1Update(context, finalcount, 8);  /* Should cause a SHA1Transform()
                          */
    for (i = 0; i < 20; i++) {
        digest[i] = (unsigned char)
            ((context->state[i >> 2] >> ((3 - (i & 3)) * 8)) &
             255);
    }
    /* Wipe variables */
    i = 0;
    memset(context->buffer, 0, 64);
    memset(context->state, 0, 20);
    memset(context->count, 0, 8);
    memset(finalcount, 0, 8);
}

void SHA1Init ( struct SHA1Context *  context)

static

Definiert in Zeile 647 der Datei sha1.c.

{
    /* SHA1 initialization constants */
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
    context->state[4] = 0xC3D2E1F0;
    context->count[0] = context->count[1] = 0;
}

static void SHA1Transform ( u32  state[5], const unsigned char  buffer[64]  )

static

Definiert in Zeile 589 der Datei sha1.c.

{
    u32 a, b, c, d, e;
    typedef union {
        unsigned char c[64];
        u32 l[16];
    } CHAR64LONG16;
    CHAR64LONG16* block;
#ifdef SHA1HANDSOFF
    u32 workspace[16];
    block = (CHAR64LONG16 *) workspace;
    memcpy(block, buffer, 64);
#else
    block = (CHAR64LONG16 *) buffer;
#endif
    /* Copy context->state[] to working vars */
    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];
    e = state[4];
    /* 4 rounds of 20 operations each. Loop unrolled. */
    R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
    R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
    R0(c,d,e,a,b, 8); R0(b,c,d,e,a, 9); R0(a,b,c,d,e,10); R0(e,a,b,c,d,11);
    R0(d,e,a,b,c,12); R0(c,d,e,a,b,13); R0(b,c,d,e,a,14); R0(a,b,c,d,e,15);
    R1(e,a,b,c,d,16); R1(d,e,a,b,c,17); R1(c,d,e,a,b,18); R1(b,c,d,e,a,19);
    R2(a,b,c,d,e,20); R2(e,a,b,c,d,21); R2(d,e,a,b,c,22); R2(c,d,e,a,b,23);
    R2(b,c,d,e,a,24); R2(a,b,c,d,e,25); R2(e,a,b,c,d,26); R2(d,e,a,b,c,27);
    R2(c,d,e,a,b,28); R2(b,c,d,e,a,29); R2(a,b,c,d,e,30); R2(e,a,b,c,d,31);
    R2(d,e,a,b,c,32); R2(c,d,e,a,b,33); R2(b,c,d,e,a,34); R2(a,b,c,d,e,35);
    R2(e,a,b,c,d,36); R2(d,e,a,b,c,37); R2(c,d,e,a,b,38); R2(b,c,d,e,a,39);
    R3(a,b,c,d,e,40); R3(e,a,b,c,d,41); R3(d,e,a,b,c,42); R3(c,d,e,a,b,43);
    R3(b,c,d,e,a,44); R3(a,b,c,d,e,45); R3(e,a,b,c,d,46); R3(d,e,a,b,c,47);
    R3(c,d,e,a,b,48); R3(b,c,d,e,a,49); R3(a,b,c,d,e,50); R3(e,a,b,c,d,51);
    R3(d,e,a,b,c,52); R3(c,d,e,a,b,53); R3(b,c,d,e,a,54); R3(a,b,c,d,e,55);
    R3(e,a,b,c,d,56); R3(d,e,a,b,c,57); R3(c,d,e,a,b,58); R3(b,c,d,e,a,59);
    R4(a,b,c,d,e,60); R4(e,a,b,c,d,61); R4(d,e,a,b,c,62); R4(c,d,e,a,b,63);
    R4(b,c,d,e,a,64); R4(a,b,c,d,e,65); R4(e,a,b,c,d,66); R4(d,e,a,b,c,67);
    R4(c,d,e,a,b,68); R4(b,c,d,e,a,69); R4(a,b,c,d,e,70); R4(e,a,b,c,d,71);
    R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
    R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);
    /* Add the working vars back into context.state[] */
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
    state[4] += e;
    /* Wipe variables */
    a = b = c = d = e = 0;
#ifdef SHA1HANDSOFF
    memset(block, 0, 64);
#endif
}

void SHA1Update ( struct SHA1Context *  context, const void *  data, u32  len  )

static

Definiert in Zeile 661 der Datei sha1.c.

{
    u32 i, j;
    const unsigned char *data = _data;

#ifdef VERBOSE
    SHAPrintContext(context, "before");
#endif
    j = (context->count[0] >> 3) & 63;
    if ((context->count[0] += len << 3) < (len << 3))
        context->count[1]++;
    context->count[1] += (len >> 29);
    if ((j + len) > 63) {
        memcpy(&context->buffer[j], data, (i = 64-j));
        SHA1Transform(context->state, context->buffer);
        for ( ; i + 63 < len; i += 64) {
            SHA1Transform(context->state, &data[i]);
        }
        j = 0;
    }
    else i = 0;
    memcpy(&context->buffer[j], &data[i], len - i);
#ifdef VERBOSE
    SHAPrintContext(context, "after ");
#endif
}

int tls_prf	(	const u8 *	secret,
		size_t	secret_len,
		const char *	label,
		const u8 *	seed,
		size_t	seed_len,
		u8 *	out,
		size_t	outlen
	)

tls_prf - Pseudo-Random Function for TLS (TLS-PRF, RFC 2246) : Key for PRF : Length of the key in bytes : A unique label for each purpose of the PRF : Seed value to bind into the key : Length of the seed : Buffer for the generated pseudo-random key : Number of bytes of key to generate Returns: 0 on success, -1 on failure.

This function is used to derive new, cryptographically separate keys from a given key in TLS. This PRF is defined in RFC 2246, Chapter 5.

Definiert in Zeile 232 der Datei sha1.c.

{
    size_t L_S1, L_S2, i;
    const u8 *S1, *S2;
    u8 A_MD5[MD5_MAC_LEN], A_SHA1[SHA1_MAC_LEN];
    u8 P_MD5[MD5_MAC_LEN], P_SHA1[SHA1_MAC_LEN];
    int MD5_pos, SHA1_pos;
    const u8 *MD5_addr[3];
    size_t MD5_len[3];
    const unsigned char *SHA1_addr[3];
    size_t SHA1_len[3];

    if (secret_len & 1)
        return -1;

    MD5_addr[0] = A_MD5;
    MD5_len[0] = MD5_MAC_LEN;
    MD5_addr[1] = (unsigned char *) label;
    MD5_len[1] = strlen(label);
    MD5_addr[2] = seed;
    MD5_len[2] = seed_len;

    SHA1_addr[0] = A_SHA1;
    SHA1_len[0] = SHA1_MAC_LEN;
    SHA1_addr[1] = (unsigned char *) label;
    SHA1_len[1] = strlen(label);
    SHA1_addr[2] = seed;
    SHA1_len[2] = seed_len;

    /* RFC 2246, Chapter 5
     * A(0) = seed, A(i) = HMAC(secret, A(i-1))
     * P_hash = HMAC(secret, A(1) + seed) + HMAC(secret, A(2) + seed) + ..
     * PRF = P_MD5(S1, label + seed) XOR P_SHA-1(S2, label + seed)
     */

    L_S1 = L_S2 = (secret_len + 1) / 2;
    S1 = secret;
    S2 = secret + L_S1;

    hmac_md5_vector(S1, L_S1, 2, &MD5_addr[1], &MD5_len[1], A_MD5);
    hmac_sha1_vector(S2, L_S2, 2, &SHA1_addr[1], &SHA1_len[1], A_SHA1);

    MD5_pos = MD5_MAC_LEN;
    SHA1_pos = SHA1_MAC_LEN;
    for (i = 0; i < outlen; i++) {
        if (MD5_pos == MD5_MAC_LEN) {
            hmac_md5_vector(S1, L_S1, 3, MD5_addr, MD5_len, P_MD5);
            MD5_pos = 0;
            hmac_md5(S1, L_S1, A_MD5, MD5_MAC_LEN, A_MD5);
        }
        if (SHA1_pos == SHA1_MAC_LEN) {
            hmac_sha1_vector(S2, L_S2, 3, SHA1_addr, SHA1_len,
                     P_SHA1);
            SHA1_pos = 0;
            hmac_sha1(S2, L_S2, A_SHA1, SHA1_MAC_LEN, A_SHA1);
        }

        out[i] = P_MD5[MD5_pos] ^ P_SHA1[SHA1_pos];

        MD5_pos++;
        SHA1_pos++;
    }

    return 0;
}