-/*
- * Copyright (c) 2007-2008,2010 Apple Inc. All Rights Reserved.
- *
- * @APPLE_LICENSE_HEADER_START@
- *
- * This file contains Original Code and/or Modifications of Original Code
- * as defined in and that are subject to the Apple Public Source License
- * Version 2.0 (the 'License'). You may not use this file except in
- * compliance with the License. Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this
- * file.
- *
- * The Original Code and all software distributed under the License are
- * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
- * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
- * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
- * Please see the License for the specific language governing rights and
- * limitations under the License.
- *
- * @APPLE_LICENSE_HEADER_END@
- */
-
-/*
- * SecDH.c - Implement the crypto required for a Diffie-Hellman key exchange.
- */
-
-#include "SecDH.h"
-#include <libDER/DER_Keys.h>
-#include <corecrypto/ccdh.h>
-#include <libDER/DER_Keys.h>
-#include <libDER/DER_Encode.h>
-#include <libDER/asn1Types.h>
-#include <libkern/OSByteOrder.h>
-#include "utilities/debugging.h"
-#include <Security/SecInternal.h>
-#include <Security/SecRandom.h>
-#include <stdlib.h>
-#include <Security/SecBase.h>
-#include <Security/SecBasePriv.h>
-
-#ifdef DEBUG
-#define DH_DEBUG 1
-#endif
-
-static inline ccdh_gp_t SecDH_gp(SecDHContext dh)
-{
- void *p = dh;
- ccdh_gp_t gp = { .gp = p };
- return gp;
-}
-
-static inline ccdh_full_ctx_t SecDH_priv(SecDHContext dh)
-{
- void *p = dh;
- cczp_t zp = { .u = p };
- cc_size s = ccn_sizeof_n(cczp_n(zp));
- ccdh_full_ctx_t priv = { .hdr = (struct ccdh_ctx_header *)(p+ccdh_gp_size(s)) };
- return priv;
-}
-
-static inline size_t SecDH_context_size(size_t p_len)
-{
- cc_size n = ccn_nof_size(p_len);
- cc_size real_p_len = ccn_sizeof_n(n);
- size_t context_size = ccdh_gp_size(real_p_len)+ccdh_full_ctx_size(real_p_len);
- return context_size;
-}
-
-/* Shared static functions. */
-
-static OSStatus
-der2OSStatus(DERReturn derReturn)
-{
- switch(derReturn)
- {
- case DR_Success: return errSecSuccess;
- case DR_EndOfSequence: return errSecDecode;
- case DR_UnexpectedTag: return errSecDecode;
- case DR_DecodeError: return errSecDecode;
- case DR_Unimplemented: return errSecUnimplemented;
- case DR_IncompleteSeq: return errSecDecode;
- case DR_ParamErr: return errSecParam;
- case DR_BufOverflow: return errSecBufferTooSmall;
- default: return errSecInternal;
- }
-}
-
-static int dhRngCallback(struct ccrng_state *rng, unsigned long outlen, void *out)
-{
- return SecRandomCopyBytes(kSecRandomDefault, outlen, out);
-}
-
-static struct ccrng_state dhrng = {
- .generate = dhRngCallback
-};
-
-OSStatus SecDHCreate(uint32_t g, const uint8_t *p, size_t p_len,
- uint32_t l, const uint8_t *recip, size_t recip_len, SecDHContext *pdh)
-{
- cc_size n = ccn_nof_size(p_len);
- size_t context_size = SecDH_context_size(p_len);
- void *context = malloc(context_size);
- bzero(context, context_size);
-
- ccdh_gp_t gp;
- gp.gp = context;
-
- CCDH_GP_N(gp) = n;
- CCDH_GP_L(gp) = l;
-
- if(ccn_read_uint(n, CCDH_GP_PRIME(gp), p_len, p))
- goto errOut;
- if(recip) {
- if(ccn_read_uint(n+1, CCDH_GP_RECIP(gp), recip_len, recip))
- goto errOut;
- gp.zp.zp->mod_prime = cczp_mod;
- } else {
- cczp_init(gp.zp);
- };
- ccn_seti(n, CCDH_GP_G(gp), g);
-
- *pdh = (SecDHContext) context;
-
- return errSecSuccess;
-
-errOut:
- SecDHDestroy(context);
- *pdh = NULL;
- return errSecInternal;
-
-}
-
-/* this used to be in libgDH */
-/*
- * Support for encoding and decoding DH parameter blocks.
- * Apple form encodes the reciprocal of the prime p.
- */
-/* PKCS3, Openssl compatible */
-typedef struct {
- DERItem p;
- DERItem g;
- DERItem l;
- DERItem recip; /* Only used in Apple Custom blocks. */
-} DER_DHParams;
-
-static const DERItemSpec DER_DHParamsItemSpecs[] =
-{
- { DER_OFFSET(DER_DHParams, p),
- ASN1_INTEGER,
- DER_DEC_NO_OPTS | DER_ENC_SIGNED_INT },
- { DER_OFFSET(DER_DHParams, g),
- ASN1_INTEGER,
- DER_DEC_NO_OPTS | DER_ENC_SIGNED_INT },
- { DER_OFFSET(DER_DHParams, l),
- ASN1_INTEGER,
- DER_DEC_OPTIONAL | DER_ENC_SIGNED_INT },
- /* Not part of PKCS3 per-se, but we add it on just for kicks. Since
- it's optional we will automatically decode any apple specific
- params, but we won't add this section unless the caller asks
- us to. */
- { DER_OFFSET(DER_DHParams, recip),
- ASN1_PRIVATE | ASN1_PRIMITIVE | 0,
- DER_DEC_OPTIONAL | DER_ENC_SIGNED_INT },
-};
-static const DERSize DER_NumDHParamsItemSpecs =
-sizeof(DER_DHParamsItemSpecs) / sizeof(DERItemSpec);
-
-
-OSStatus SecDHCreateFromParameters(const uint8_t *params,
- size_t params_len, SecDHContext *pdh)
-{
- DERReturn drtn;
- DERItem paramItem = {(DERByte *)params, params_len};
- DER_DHParams decodedParams;
- uint32_t l;
-
- drtn = DERParseSequence(¶mItem,
- DER_NumDHParamsItemSpecs, DER_DHParamsItemSpecs,
- &decodedParams, sizeof(decodedParams));
- if(drtn)
- return drtn;
-
- drtn = DERParseInteger(&decodedParams.l, &l);
- if(drtn)
- return drtn;
- cc_size n = ccn_nof_size(decodedParams.p.length);
- cc_size p_len = ccn_sizeof_n(n);
- size_t context_size = ccdh_gp_size(p_len)+ccdh_full_ctx_size(p_len);
- void *context = malloc(context_size);
- if(context==NULL)
- return errSecAllocate;
-
- bzero(context, context_size);
-
- ccdh_gp_t gp;
- gp.gp = context;
-
- CCDH_GP_N(gp) = n;
- CCDH_GP_L(gp) = l;
-
- if(ccn_read_uint(n, CCDH_GP_PRIME(gp), decodedParams.p.length, decodedParams.p.data))
- goto errOut;
- if(decodedParams.recip.length) {
- if(ccn_read_uint(n+1, CCDH_GP_RECIP(gp), decodedParams.recip.length, decodedParams.recip.data))
- goto errOut;
- gp.zp.zp->mod_prime = cczp_mod;
- } else {
- cczp_init(gp.zp);
- };
-
- if(ccn_read_uint(n, CCDH_GP_G(gp), decodedParams.g.length, decodedParams.g.data))
- goto errOut;
-
- *pdh = (SecDHContext) context;
- return errSecSuccess;
-
-errOut:
- SecDHDestroy(context);
- *pdh = NULL;
- return errSecInvalidKey;
-}
-
-OSStatus SecDHCreateFromAlgorithmId(const uint8_t *alg, size_t alg_len,
- SecDHContext *pdh) {
- DERAlgorithmId algorithmId;
- DERItem algId;
-
- algId.data = (uint8_t *)alg;
- algId.length = alg_len;
-
- DERReturn drtn = DERParseSequence(&algId,
- DERNumAlgorithmIdItemSpecs, DERAlgorithmIdItemSpecs,
- &algorithmId, sizeof(algorithmId));
- if (drtn != DR_Success)
- return der2OSStatus(drtn);
-
- return SecDHCreateFromParameters(algorithmId.params.data,
- algorithmId.params.length, pdh);
-}
-
-size_t SecDHGetMaxKeyLength(SecDHContext dh) {
- cczp_const_t zp;
- zp.u = (cc_unit *)dh;
-
- return ccn_sizeof_n(cczp_n(zp));
-}
-
-
-OSStatus SecDHGenerateKeypair(SecDHContext dh, uint8_t *pub_key,
- size_t *pub_key_len)
-{
- int result;
- ccdh_gp_t gp = SecDH_gp(dh);
- ccdh_full_ctx_t priv = SecDH_priv(dh);
-
- if((result = ccdh_generate_key(gp, &dhrng, priv)))
- return result;
-
- /* output y as a big endian byte buffer */
- size_t ylen = ccn_write_uint_size(ccdh_gp_n(gp), ccdh_ctx_y(priv));
- if(*pub_key_len < ylen)
- return errSecBufferTooSmall;
- ccn_write_uint(ccdh_gp_n(gp),ccdh_ctx_y(priv), ylen, pub_key);
- *pub_key_len = ylen;
-
- return errSecSuccess;
-}
-
-OSStatus SecDHComputeKey(SecDHContext dh,
- const uint8_t *pub_key, size_t pub_key_len,
- uint8_t *computed_key, size_t *computed_key_len)
-{
- ccdh_gp_t gp = SecDH_gp(dh);
- ccdh_full_ctx_t priv = SecDH_priv(dh);
- ccdh_pub_ctx_decl_gp(gp, pub);
- cc_size n = ccdh_gp_n(gp);
- cc_unit r[n];
-
- if(ccdh_import_pub(gp, pub_key_len, pub_key, pub))
- return errSecInvalidKey;
-
- if(ccdh_compute_key(priv, pub, r))
- return errSecInvalidKey;
-
- ccn_write_uint(n, r, *computed_key_len, computed_key);
- size_t out_size = ccn_write_uint_size(n, r);
- if(out_size < *computed_key_len)
- *computed_key_len=out_size;
-
- return errSecSuccess;
-}
-
-void SecDHDestroy(SecDHContext dh) {
- /* Zero out key material. */
- ccdh_gp_t gp = SecDH_gp(dh);
- cc_size p_len = ccn_sizeof_n(ccdh_gp_n(gp));
- size_t context_size = SecDH_context_size(p_len);
-
- bzero(dh, context_size);
- free(dh);
-}
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