1 files changed, 668 insertions, 0 deletions

diff --git a/src/lib/libcrypto/engine/eng_rsax.c b/src/lib/libcrypto/engine/eng_rsax.c
new file mode 100644
index 0000000000..96e63477ee
--- /dev/null
+++ b/src/lib/libcrypto/engine/eng_rsax.c
@@ -0,0 +1,668 @@
+/* crypto/engine/eng_rsax.c */
+/* Copyright (c) 2010-2010 Intel Corp.
+ *   Author: Vinodh.Gopal@intel.com
+ *           Jim Guilford
+ *           Erdinc.Ozturk@intel.com
+ *           Maxim.Perminov@intel.com
+ *           Ying.Huang@intel.com
+ *
+ * More information about algorithm used can be found at:
+ *   http://www.cse.buffalo.edu/srds2009/escs2009_submission_Gopal.pdf
+ */
+/* ====================================================================
+ * Copyright (c) 1999-2001 The OpenSSL Project.  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. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    licensing@OpenSSL.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED 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 OpenSSL PROJECT OR
+ * ITS 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.
+ * ====================================================================
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com).  This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com).
+ */
+
+#include <openssl/opensslconf.h>
+
+#include <stdio.h>
+#include <string.h>
+#include <openssl/crypto.h>
+#include <openssl/buffer.h>
+#include <openssl/engine.h>
+#ifndef OPENSSL_NO_RSA
+#include <openssl/rsa.h>
+#endif
+#include <openssl/bn.h>
+#include <openssl/err.h>
+
+/* RSAX is available **ONLY* on x86_64 CPUs */
+#undef COMPILE_RSAX
+
+#if (defined(__x86_64) || defined(__x86_64__) || \
+     defined(_M_AMD64) || defined (_M_X64)) && !defined(OPENSSL_NO_ASM)
+#define COMPILE_RSAX
+static ENGINE *ENGINE_rsax (void);
+#endif
+
+void ENGINE_load_rsax (void)
+        {
+/* On non-x86 CPUs it just returns. */
+#ifdef COMPILE_RSAX
+        ENGINE *toadd = ENGINE_rsax();
+        if(!toadd) return;
+        ENGINE_add(toadd);
+        ENGINE_free(toadd);
+        ERR_clear_error();
+#endif
+        }
+
+#ifdef COMPILE_RSAX
+#define E_RSAX_LIB_NAME "rsax engine"
+
+static int e_rsax_destroy(ENGINE *e);
+static int e_rsax_init(ENGINE *e);
+static int e_rsax_finish(ENGINE *e);
+static int e_rsax_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)(void));
+
+#ifndef OPENSSL_NO_RSA
+/* RSA stuff */
+static int e_rsax_rsa_mod_exp(BIGNUM *r, const BIGNUM *I, RSA *rsa, BN_CTX *ctx);
+static int e_rsax_rsa_finish(RSA *r);
+#endif
+
+static const ENGINE_CMD_DEFN e_rsax_cmd_defns[] = {
+        {0, NULL, NULL, 0}
+        };
+
+#ifndef OPENSSL_NO_RSA
+/* Our internal RSA_METHOD that we provide pointers to */
+static RSA_METHOD e_rsax_rsa =
+        {
+        "Intel RSA-X method",
+        NULL,
+        NULL,
+        NULL,
+        NULL,
+        e_rsax_rsa_mod_exp,
+        NULL,
+        NULL,
+        e_rsax_rsa_finish,
+        RSA_FLAG_CACHE_PUBLIC|RSA_FLAG_CACHE_PRIVATE,
+        NULL,
+        NULL,
+        NULL
+        };
+#endif
+
+/* Constants used when creating the ENGINE */
+static const char *engine_e_rsax_id = "rsax";
+static const char *engine_e_rsax_name = "RSAX engine support";
+
+/* This internal function is used by ENGINE_rsax() */
+static int bind_helper(ENGINE *e)
+        {
+#ifndef OPENSSL_NO_RSA
+        const RSA_METHOD *meth1;
+#endif
+        if(!ENGINE_set_id(e, engine_e_rsax_id) ||
+                        !ENGINE_set_name(e, engine_e_rsax_name) ||
+#ifndef OPENSSL_NO_RSA
+                        !ENGINE_set_RSA(e, &e_rsax_rsa) ||
+#endif
+                        !ENGINE_set_destroy_function(e, e_rsax_destroy) ||
+                        !ENGINE_set_init_function(e, e_rsax_init) ||
+                        !ENGINE_set_finish_function(e, e_rsax_finish) ||
+                        !ENGINE_set_ctrl_function(e, e_rsax_ctrl) ||
+                        !ENGINE_set_cmd_defns(e, e_rsax_cmd_defns))
+                return 0;
+
+#ifndef OPENSSL_NO_RSA
+        meth1 = RSA_PKCS1_SSLeay();
+        e_rsax_rsa.rsa_pub_enc = meth1->rsa_pub_enc;
+        e_rsax_rsa.rsa_pub_dec = meth1->rsa_pub_dec;
+        e_rsax_rsa.rsa_priv_enc = meth1->rsa_priv_enc;
+        e_rsax_rsa.rsa_priv_dec = meth1->rsa_priv_dec;
+        e_rsax_rsa.bn_mod_exp = meth1->bn_mod_exp;
+#endif
+        return 1;
+        }
+
+static ENGINE *ENGINE_rsax(void)
+        {
+        ENGINE *ret = ENGINE_new();
+        if(!ret)
+                return NULL;
+        if(!bind_helper(ret))
+                {
+                ENGINE_free(ret);
+                return NULL;
+                }
+        return ret;
+        }
+
+#ifndef OPENSSL_NO_RSA
+/* Used to attach our own key-data to an RSA structure */
+static int rsax_ex_data_idx = -1;
+#endif
+
+static int e_rsax_destroy(ENGINE *e)
+        {
+        return 1;
+        }
+
+/* (de)initialisation functions. */
+static int e_rsax_init(ENGINE *e)
+        {
+#ifndef OPENSSL_NO_RSA
+        if (rsax_ex_data_idx == -1)
+                rsax_ex_data_idx = RSA_get_ex_new_index(0,
+                        NULL,
+                        NULL, NULL, NULL);
+#endif
+        if (rsax_ex_data_idx  == -1)
+                return 0;
+        return 1;
+        }
+
+static int e_rsax_finish(ENGINE *e)
+        {
+        return 1;
+        }
+
+static int e_rsax_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)(void))
+        {
+        int to_return = 1;
+
+        switch(cmd)
+                {
+        /* The command isn't understood by this engine */
+        default:
+                to_return = 0;
+                break;
+                }
+
+        return to_return;
+        }
+
+
+#ifndef OPENSSL_NO_RSA
+
+#ifdef _WIN32
+typedef unsigned __int64 UINT64;
+#else
+typedef unsigned long long UINT64;
+#endif
+typedef unsigned short UINT16;
+
+/* Table t is interleaved in the following manner:
+ * The order in memory is t[0][0], t[0][1], ..., t[0][7], t[1][0], ...
+ * A particular 512-bit value is stored in t[][index] rather than the more
+ * normal t[index][]; i.e. the qwords of a particular entry in t are not
+ * adjacent in memory
+ */
+
+/* Init BIGNUM b from the interleaved UINT64 array */
+static int interleaved_array_to_bn_512(BIGNUM* b, UINT64 *array);
+
+/* Extract array elements from BIGNUM b
+ * To set the whole array from b, call with n=8
+ */
+static int bn_extract_to_array_512(const BIGNUM* b, unsigned int n, UINT64 *array);
+
+struct mod_ctx_512 {
+    UINT64 t[8][8];
+    UINT64 m[8];
+    UINT64 m1[8]; /* 2^278 % m */
+    UINT64 m2[8]; /* 2^640 % m */
+    UINT64 k1[2]; /* (- 1/m) % 2^128 */
+};
+
+static int mod_exp_pre_compute_data_512(UINT64 *m, struct mod_ctx_512 *data);
+
+void mod_exp_512(UINT64 *result, /* 512 bits, 8 qwords */
+                 UINT64 *g,      /* 512 bits, 8 qwords */
+                 UINT64 *exp,    /* 512 bits, 8 qwords */
+                 struct mod_ctx_512 *data);
+
+typedef struct st_e_rsax_mod_ctx
+{
+  UINT64 type;
+  union {
+    struct mod_ctx_512 b512;
+  } ctx;
+
+} E_RSAX_MOD_CTX;
+
+static E_RSAX_MOD_CTX *e_rsax_get_ctx(RSA *rsa, int idx, BIGNUM* m)
+{
+        E_RSAX_MOD_CTX *hptr;
+
+        if (idx < 0 || idx > 2)
+           return NULL;
+
+        hptr = RSA_get_ex_data(rsa, rsax_ex_data_idx);
+        if (!hptr) {
+            hptr = OPENSSL_malloc(3*sizeof(E_RSAX_MOD_CTX));
+            if (!hptr) return NULL;
+            hptr[2].type = hptr[1].type= hptr[0].type = 0;
+            RSA_set_ex_data(rsa, rsax_ex_data_idx, hptr);
+        }
+
+        if (hptr[idx].type == (UINT64)BN_num_bits(m))
+            return hptr+idx;
+
+        if (BN_num_bits(m) == 512) {
+            UINT64 _m[8];
+            bn_extract_to_array_512(m, 8, _m);
+            memset( &hptr[idx].ctx.b512, 0, sizeof(struct mod_ctx_512));
+            mod_exp_pre_compute_data_512(_m, &hptr[idx].ctx.b512);
+        }
+
+        hptr[idx].type = BN_num_bits(m);
+        return hptr+idx;
+}
+
+static int e_rsax_rsa_finish(RSA *rsa)
+        {
+        E_RSAX_MOD_CTX *hptr = RSA_get_ex_data(rsa, rsax_ex_data_idx);
+        if(hptr)
+                {
+                OPENSSL_free(hptr);
+                RSA_set_ex_data(rsa, rsax_ex_data_idx, NULL);
+                }
+        if (rsa->_method_mod_n)
+                BN_MONT_CTX_free(rsa->_method_mod_n);
+        if (rsa->_method_mod_p)
+                BN_MONT_CTX_free(rsa->_method_mod_p);
+        if (rsa->_method_mod_q)
+                BN_MONT_CTX_free(rsa->_method_mod_q);
+        return 1;
+        }
+
+
+static int e_rsax_bn_mod_exp(BIGNUM *r, const BIGNUM *g, const BIGNUM *e,
+                    const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont, E_RSAX_MOD_CTX* rsax_mod_ctx )
+{
+        if (rsax_mod_ctx && BN_get_flags(e, BN_FLG_CONSTTIME) != 0) {
+           if (BN_num_bits(m) == 512) {
+                UINT64 _r[8];
+                UINT64 _g[8];
+                UINT64 _e[8];
+
+                /* Init the arrays from the BIGNUMs */
+                bn_extract_to_array_512(g, 8, _g);
+                bn_extract_to_array_512(e, 8, _e);
+
+                mod_exp_512(_r, _g, _e, &rsax_mod_ctx->ctx.b512);
+                /* Return the result in the BIGNUM */
+                interleaved_array_to_bn_512(r, _r);
+                return 1;
+           }
+        }
+
+        return BN_mod_exp_mont(r, g, e, m, ctx, in_mont);
+}
+
+/* Declares for the Intel CIAP 512-bit / CRT / 1024 bit RSA modular
+ * exponentiation routine precalculations and a structure to hold the
+ * necessary values.  These files are meant to live in crypto/rsa/ in
+ * the target openssl.
+ */
+
+/*
+ * Local method: extracts a piece from a BIGNUM, to fit it into
+ * an array. Call with n=8 to extract an entire 512-bit BIGNUM
+ */
+static int bn_extract_to_array_512(const BIGNUM* b, unsigned int n, UINT64 *array)
+{
+        int i;
+        UINT64 tmp;
+        unsigned char bn_buff[64];
+        memset(bn_buff, 0, 64);
+        if (BN_num_bytes(b) > 64) {
+                printf ("Can't support this byte size\n");
+                return 0; }
+        if (BN_num_bytes(b)!=0) {
+                if (!BN_bn2bin(b, bn_buff+(64-BN_num_bytes(b)))) {
+                        printf ("Error's in bn2bin\n");
+                        /* We have to error, here */
+                        return 0; } }
+        while (n-- > 0) {
+                array[n] = 0;
+                for (i=7; i>=0; i--) {
+                        tmp = bn_buff[63-(n*8+i)];
+                        array[n] |= tmp << (8*i); } }
+        return 1;
+}
+
+/* Init a 512-bit BIGNUM from the UINT64*_ (8 * 64) interleaved array */
+static int interleaved_array_to_bn_512(BIGNUM* b, UINT64 *array)
+{
+        unsigned char tmp[64];
+        int n=8;
+        int i;
+        while (n-- > 0) {
+                for (i = 7; i>=0; i--) {
+                        tmp[63-(n*8+i)] = (unsigned char)(array[n]>>(8*i)); } }
+        BN_bin2bn(tmp, 64, b);
+        return 0;
+}
+
+
+/* The main 512bit precompute call */
+static int mod_exp_pre_compute_data_512(UINT64 *m, struct mod_ctx_512 *data)
+ {
+    BIGNUM two_768, two_640, two_128, two_512, tmp, _m, tmp2;
+
+    /* We need a BN_CTX for the modulo functions */
+    BN_CTX* ctx;
+    /* Some tmps */
+    UINT64 _t[8];
+    int i, j, ret = 0;
+
+    /* Init _m with m */
+    BN_init(&_m);
+    interleaved_array_to_bn_512(&_m, m);
+    memset(_t, 0, 64);
+
+    /* Inits */
+    BN_init(&two_768);
+    BN_init(&two_640);
+    BN_init(&two_128);
+    BN_init(&two_512);
+    BN_init(&tmp);
+    BN_init(&tmp2);
+
+    /* Create our context */
+    if ((ctx=BN_CTX_new()) == NULL) { goto err; }
+        BN_CTX_start(ctx);
+
+    /*
+     * For production, if you care, these only need to be set once,
+     * and may be made constants.
+     */
+    BN_lshift(&two_768, BN_value_one(), 768);
+    BN_lshift(&two_640, BN_value_one(), 640);
+    BN_lshift(&two_128, BN_value_one(), 128);
+    BN_lshift(&two_512, BN_value_one(), 512);
+
+    if (0 == (m[7] & 0x8000000000000000)) {
+        exit(1);
+    }
+    if (0 == (m[0] & 0x1)) { /* Odd modulus required for Mont */
+        exit(1);
+    }
+
+    /* Precompute m1 */
+    BN_mod(&tmp, &two_768, &_m, ctx);
+    if (!bn_extract_to_array_512(&tmp, 8, &data->m1[0])) {
+            goto err; }
+
+    /* Precompute m2 */
+    BN_mod(&tmp, &two_640, &_m, ctx);
+    if (!bn_extract_to_array_512(&tmp, 8, &data->m2[0])) {
+            goto err;
+    }
+
+    /*
+     * Precompute k1, a 128b number = ((-1)* m-1 ) mod 2128; k1 should
+     * be non-negative.
+     */
+    BN_mod_inverse(&tmp, &_m, &two_128, ctx);
+    if (!BN_is_zero(&tmp)) { BN_sub(&tmp, &two_128, &tmp); }
+    if (!bn_extract_to_array_512(&tmp, 2, &data->k1[0])) {
+            goto err; }
+
+    /* Precompute t */
+    for (i=0; i<8; i++) {
+        BN_zero(&tmp);
+        if (i & 1) { BN_add(&tmp, &two_512, &tmp); }
+        if (i & 2) { BN_add(&tmp, &two_512, &tmp); }
+        if (i & 4) { BN_add(&tmp, &two_640, &tmp); }
+
+        BN_nnmod(&tmp2, &tmp, &_m, ctx);
+        if (!bn_extract_to_array_512(&tmp2, 8, _t)) {
+                goto err; }
+        for (j=0; j<8; j++) data->t[j][i] = _t[j]; }
+
+    /* Precompute m */
+    for (i=0; i<8; i++) {
+        data->m[i] = m[i]; }
+
+    ret = 1;
+
+err:
+    /* Cleanup */
+        if (ctx != NULL) {
+                BN_CTX_end(ctx); BN_CTX_free(ctx); }
+    BN_free(&two_768);
+    BN_free(&two_640);
+    BN_free(&two_128);
+    BN_free(&two_512);
+    BN_free(&tmp);
+    BN_free(&tmp2);
+    BN_free(&_m);
+
+    return ret;
+}
+
+
+static int e_rsax_rsa_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
+        {
+        BIGNUM *r1,*m1,*vrfy;
+        BIGNUM local_dmp1,local_dmq1,local_c,local_r1;
+        BIGNUM *dmp1,*dmq1,*c,*pr1;
+        int ret=0;
+
+        BN_CTX_start(ctx);
+        r1 = BN_CTX_get(ctx);
+        m1 = BN_CTX_get(ctx);
+        vrfy = BN_CTX_get(ctx);
+
+        {
+                BIGNUM local_p, local_q;
+                BIGNUM *p = NULL, *q = NULL;
+                int error = 0;
+
+                /* Make sure BN_mod_inverse in Montgomery
+                 * intialization uses the BN_FLG_CONSTTIME flag
+                 * (unless RSA_FLAG_NO_CONSTTIME is set)
+                 */
+                if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
+                        {
+                        BN_init(&local_p);
+                        p = &local_p;
+                        BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
+
+                        BN_init(&local_q);
+                        q = &local_q;
+                        BN_with_flags(q, rsa->q, BN_FLG_CONSTTIME);
+                        }
+                else
+                        {
+                        p = rsa->p;
+                        q = rsa->q;
+                        }
+
+                if (rsa->flags & RSA_FLAG_CACHE_PRIVATE)
+                        {
+                        if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_p, CRYPTO_LOCK_RSA, p, ctx))
+                                error = 1;
+                        if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_q, CRYPTO_LOCK_RSA, q, ctx))
+                                error = 1;
+                        }
+
+                /* clean up */
+                if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
+                        {
+                        BN_free(&local_p);
+                        BN_free(&local_q);
+                        }
+                if ( error )
+                        goto err;
+        }
+
+        if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
+                if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
+                        goto err;
+
+        /* compute I mod q */
+        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
+                {
+                c = &local_c;
+                BN_with_flags(c, I, BN_FLG_CONSTTIME);
+                if (!BN_mod(r1,c,rsa->q,ctx)) goto err;
+                }
+        else
+                {
+                if (!BN_mod(r1,I,rsa->q,ctx)) goto err;
+                }
+
+        /* compute r1^dmq1 mod q */
+        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
+                {
+                dmq1 = &local_dmq1;
+                BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
+                }
+        else
+                dmq1 = rsa->dmq1;
+
+        if (!e_rsax_bn_mod_exp(m1,r1,dmq1,rsa->q,ctx,
+                rsa->_method_mod_q, e_rsax_get_ctx(rsa, 0, rsa->q) )) goto err;
+
+        /* compute I mod p */
+        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
+                {
+                c = &local_c;
+                BN_with_flags(c, I, BN_FLG_CONSTTIME);
+                if (!BN_mod(r1,c,rsa->p,ctx)) goto err;
+                }
+        else
+                {
+                if (!BN_mod(r1,I,rsa->p,ctx)) goto err;
+                }
+
+        /* compute r1^dmp1 mod p */
+        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
+                {
+                dmp1 = &local_dmp1;
+                BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
+                }
+        else
+                dmp1 = rsa->dmp1;
+
+        if (!e_rsax_bn_mod_exp(r0,r1,dmp1,rsa->p,ctx,
+                rsa->_method_mod_p, e_rsax_get_ctx(rsa, 1, rsa->p) )) goto err;
+
+        if (!BN_sub(r0,r0,m1)) goto err;
+        /* This will help stop the size of r0 increasing, which does
+         * affect the multiply if it optimised for a power of 2 size */
+        if (BN_is_negative(r0))
+                if (!BN_add(r0,r0,rsa->p)) goto err;
+
+        if (!BN_mul(r1,r0,rsa->iqmp,ctx)) goto err;
+
+        /* Turn BN_FLG_CONSTTIME flag on before division operation */
+        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
+                {
+                pr1 = &local_r1;
+                BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
+                }
+        else
+                pr1 = r1;
+        if (!BN_mod(r0,pr1,rsa->p,ctx)) goto err;
+
+        /* If p < q it is occasionally possible for the correction of
+         * adding 'p' if r0 is negative above to leave the result still
+         * negative. This can break the private key operations: the following
+         * second correction should *always* correct this rare occurrence.
+         * This will *never* happen with OpenSSL generated keys because
+         * they ensure p > q [steve]
+         */
+        if (BN_is_negative(r0))
+                if (!BN_add(r0,r0,rsa->p)) goto err;
+        if (!BN_mul(r1,r0,rsa->q,ctx)) goto err;
+        if (!BN_add(r0,r1,m1)) goto err;
+
+        if (rsa->e && rsa->n)
+                {
+                if (!e_rsax_bn_mod_exp(vrfy,r0,rsa->e,rsa->n,ctx,rsa->_method_mod_n, e_rsax_get_ctx(rsa, 2, rsa->n) ))
+                    goto err;
+
+                /* If 'I' was greater than (or equal to) rsa->n, the operation
+                 * will be equivalent to using 'I mod n'. However, the result of
+                 * the verify will *always* be less than 'n' so we don't check
+                 * for absolute equality, just congruency. */
+                if (!BN_sub(vrfy, vrfy, I)) goto err;
+                if (!BN_mod(vrfy, vrfy, rsa->n, ctx)) goto err;
+                if (BN_is_negative(vrfy))
+                        if (!BN_add(vrfy, vrfy, rsa->n)) goto err;
+                if (!BN_is_zero(vrfy))
+                        {
+                        /* 'I' and 'vrfy' aren't congruent mod n. Don't leak
+                         * miscalculated CRT output, just do a raw (slower)
+                         * mod_exp and return that instead. */
+
+                        BIGNUM local_d;
+                        BIGNUM *d = NULL;
+
+                        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
+                                {
+                                d = &local_d;
+                                BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
+                                }
+                        else
+                                d = rsa->d;
+                        if (!e_rsax_bn_mod_exp(r0,I,d,rsa->n,ctx,
+                                                   rsa->_method_mod_n, e_rsax_get_ctx(rsa, 2, rsa->n) )) goto err;
+                        }
+                }
+        ret=1;
+
+err:
+        BN_CTX_end(ctx);
+
+        return ret;
+        }
+#endif /* !OPENSSL_NO_RSA */
+#endif /* !COMPILE_RSAX */