Commit 8a0a12e5 authored by Dr. Stephen Henson's avatar Dr. Stephen Henson
Browse files

PSK premaster secret derivation. 



Move PSK premaster secret algorithm to ssl_generate_master secret so
existing key exchange code can be used and modified slightly to add
the PSK wrapping structure.

Reviewed-by: default avatarMatt Caswell <matt@openssl.org>
parent 85269210

ssl/s3_lib.c

+46 −7
Original line number Diff line number Diff line
@@ -4259,13 +4259,52 @@ int ssl_fill_hello_random(SSL *s, int server, unsigned char *result, int len) 
int ssl_generate_master_secret(SSL *s, unsigned char *pms, size_t pmslen,

                               int free_pms)

{

#ifndef OPENSSL_NO_PSK

    unsigned long alg_k = s->s3->tmp.new_cipher->algorithm_mkey;

    if (alg_k & SSL_PSK) {

        unsigned char *pskpms, *t;

        size_t psklen = s->s3->tmp.psklen;

        size_t pskpmslen;



        /* create PSK premaster_secret */



        /* For plain PSK "other_secret" is psklen zeroes */

        if (alg_k & SSL_kPSK)

            pmslen = psklen;



        pskpmslen = 4 + pmslen + psklen;

        pskpms = OPENSSL_malloc(pskpmslen);

        if (pskpms == NULL)

            return 0;

        t = pskpms;

        s2n(pmslen, t);

        if (alg_k & SSL_kPSK)

            memset(t, 0, pmslen);

        else

            memcpy(t, pms, pmslen);

        t += pmslen;

        s2n(psklen, t);

        memcpy(t, s->s3->tmp.psk, psklen);



        OPENSSL_clear_free(s->s3->tmp.psk, psklen);

        s->s3->tmp.psk = NULL;

        s->session->master_key_length =

        s->method->ssl3_enc->generate_master_secret(s, s->session->master_key,

            s->method->ssl3_enc->generate_master_secret(s,

                                                        s->session->master_key,

                                                        pskpms, pskpmslen);

        OPENSSL_clear_free(pskpms, pskpmslen);

    } else

#endif

        s->session->master_key_length =

            s->method->ssl3_enc->generate_master_secret(s,

                                                        s->session->master_key,

                                                        pms, pmslen);

    if (pms) {

        if (free_pms)

            OPENSSL_clear_free(pms, pmslen);

        else

            OPENSSL_cleanse(pms, pmslen);

    }

    if (s->server == 0)

        s->s3->tmp.pms = NULL;

    return s->session->master_key_length >= 0;