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380b232ec9
libtpms/src/tpm2/crypto/openssl/CryptEccKeyExchange.c
Stefan Berger 380b232ec9 rev150: Code comment changes only 
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
2019-01-03 13:15:44 -05:00

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/********************************************************************************/
/* */
/* Functions that are used for the two-phase, ECC, key-exchange protocols */
/* Written by Ken Goldman */
/* IBM Thomas J. Watson Research Center */
/* $Id: CryptEccKeyExchange.c 1370 2018-11-02 19:39:07Z kgoldman $ */
/* */
/* Licenses and Notices */
/* */
/* 1. Copyright Licenses: */
/* */
/* - Trusted Computing Group (TCG) grants to the user of the source code in */
/* this specification (the "Source Code") a worldwide, irrevocable, */
/* nonexclusive, royalty free, copyright license to reproduce, create */
/* derivative works, distribute, display and perform the Source Code and */
/* derivative works thereof, and to grant others the rights granted herein. */
/* */
/* - The TCG grants to the user of the other parts of the specification */
/* (other than the Source Code) the rights to reproduce, distribute, */
/* display, and perform the specification solely for the purpose of */
/* developing products based on such documents. */
/* */
/* 2. Source Code Distribution Conditions: */
/* */
/* - Redistributions of Source Code must retain the above copyright licenses, */
/* this list of conditions and the following disclaimers. */
/* */
/* - Redistributions in binary form must reproduce the above copyright */
/* licenses, this list of conditions and the following disclaimers in the */
/* documentation and/or other materials provided with the distribution. */
/* */
/* 3. Disclaimers: */
/* */
/* - THE COPYRIGHT LICENSES SET FORTH ABOVE DO NOT REPRESENT ANY FORM OF */
/* LICENSE OR WAIVER, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, WITH */
/* RESPECT TO PATENT RIGHTS HELD BY TCG MEMBERS (OR OTHER THIRD PARTIES) */
/* THAT MAY BE NECESSARY TO IMPLEMENT THIS SPECIFICATION OR OTHERWISE. */
/* Contact TCG Administration (admin@trustedcomputinggroup.org) for */
/* information on specification licensing rights available through TCG */
/* membership agreements. */
/* */
/* - THIS SPECIFICATION IS PROVIDED "AS IS" WITH NO EXPRESS OR IMPLIED */
/* WARRANTIES WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR */
/* FITNESS FOR A PARTICULAR PURPOSE, ACCURACY, COMPLETENESS, OR */
/* NONINFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS, OR ANY WARRANTY */
/* OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION OR SAMPLE. */
/* */
/* - Without limitation, TCG and its members and licensors disclaim all */
/* liability, including liability for infringement of any proprietary */
/* rights, relating to use of information in this specification and to the */
/* implementation of this specification, and TCG disclaims all liability for */
/* cost of procurement of substitute goods or services, lost profits, loss */
/* of use, loss of data or any incidental, consequential, direct, indirect, */
/* or special damages, whether under contract, tort, warranty or otherwise, */
/* arising in any way out of use or reliance upon this specification or any */
/* information herein. */
/* */
/* (c) Copyright IBM Corp. and others, 2016 - 2018 */
/* */
/********************************************************************************/
/* 10.2.11 CryptEccKeyExchange.c */
#include "Tpm.h"
/* libtpms added begin */
LIB_EXPORT TPM_RC
SM2KeyExchange(
TPMS_ECC_POINT *outZ, // OUT: the computed point
TPM_ECC_CURVE curveId, // IN: the curve for the computations
TPM2B_ECC_PARAMETER *dsAIn, // IN: static private TPM key
TPM2B_ECC_PARAMETER *deAIn, // IN: ephemeral private TPM key
TPMS_ECC_POINT *QsBIn, // IN: static public party B key
TPMS_ECC_POINT *QeBIn // IN: ephemeral public party B key
);
/* libtpms added end */
#if CC_ZGen_2Phase == YES
#if ALG_ECMQV
/* 10.2.11.1.1 avf1() */
/* This function does the associated value computation required by MQV key exchange. Process: */
/* a) Convert xQ to an integer xqi using the convention specified in Appendix C.3. */
/* b) Calculate xqm = xqi mod 2^ceil(f/2) (where f = ceil(log2(n)). */
/* c) Calculate the associate value function avf(Q) = xqm + 2ceil(f / 2) */
/* Always returns TRUE(1). */
static BOOL
avf1(
bigNum bnX, // IN/OUT: the reduced value
bigNum bnN // IN: the order of the curve
)
{
// compute f = 2^(ceil(ceil(log2(n)) / 2))
int f = (BnSizeInBits(bnN) + 1) / 2;
// x' = 2^f + (x mod 2^f)
BnMaskBits(bnX, f); // This is mod 2*2^f but it doesn't matter because
// the next operation will SET the extra bit anyway
BnSetBit(bnX, f);
return TRUE;
}
/* 10.2.11.1.2 C_2_2_MQV() */
/* This function performs the key exchange defined in SP800-56A 6.1.1.4 Full MQV, C(2, 2, ECC
MQV). */
/* CAUTION: Implementation of this function may require use of essential claims in patents not owned
by TCG members. */
/* Points QsB() and QeB() are required to be on the curve of inQsA. The function will fail, possibly
catastrophically, if this is not the case. */
/* Error Returns Meaning */
/* TPM_RC_NO_RESULT the value for dsA does not give a valid point on the curve */
static TPM_RC
C_2_2_MQV(
TPMS_ECC_POINT *outZ, // OUT: the computed point
TPM_ECC_CURVE curveId, // IN: the curve for the computations
TPM2B_ECC_PARAMETER *dsA, // IN: static private TPM key
TPM2B_ECC_PARAMETER *deA, // IN: ephemeral private TPM key
TPMS_ECC_POINT *QsB, // IN: static public party B key
TPMS_ECC_POINT *QeB // IN: ephemeral public party B key
)
{
CURVE_INITIALIZED(E, curveId);
const ECC_CURVE_DATA *C;
POINT(pQeA);
POINT_INITIALIZED(pQeB, QeB);
POINT_INITIALIZED(pQsB, QsB);
ECC_NUM(bnTa);
ECC_INITIALIZED(bnDeA, deA);
ECC_INITIALIZED(bnDsA, dsA);
ECC_NUM(bnN);
ECC_NUM(bnXeB);
TPM_RC retVal;
//
// Parameter checks
if(E == NULL)
ERROR_RETURN(TPM_RC_VALUE);
pAssert(outZ != NULL && pQeB != NULL && pQsB != NULL && deA != NULL
&& dsA != NULL);
C = AccessCurveData(E);
// Process:
// 1. implicitsigA = (de,A + avf(Qe,A)ds,A ) mod n.
// 2. P = h(implicitsigA)(Qe,B + avf(Qe,B)Qs,B).
// 3. If P = O, output an error indicator.
// 4. Z=xP, where xP is the x-coordinate of P.
// Compute the public ephemeral key pQeA = [de,A]G
if((retVal = BnPointMult(pQeA, CurveGetG(C), bnDeA, NULL, NULL, E))
!= TPM_RC_SUCCESS)
goto Exit;
// 1. implicitsigA = (de,A + avf(Qe,A)ds,A ) mod n.
// tA := (ds,A + de,A avf(Xe,A)) mod n (3)
// Compute 'tA' = ('deA' + 'dsA' avf('XeA')) mod n
// Ta = avf(XeA);
BnCopy(bnTa, pQeA->x);
avf1(bnTa, bnN);
// do Ta = ds,A * Ta mod n = dsA * avf(XeA) mod n
BnModMult(bnTa, bnDsA, bnTa, bnN);
// now Ta = deA + Ta mod n = deA + dsA * avf(XeA) mod n
BnAdd(bnTa, bnTa, bnDeA);
BnMod(bnTa, bnN);
// 2. P = h(implicitsigA)(Qe,B + avf(Qe,B)Qs,B).
// Put this in because almost every case of h is == 1 so skip the call when
// not necessary.
if(!BnEqualWord(CurveGetCofactor(C), 1))
// Cofactor is not 1 so compute Ta := Ta * h mod n
BnModMult(bnTa, bnTa, CurveGetCofactor(C), CurveGetOrder(C));
// Now that 'tA' is (h * 'tA' mod n)
// 'outZ' = (tA)(Qe,B + avf(Qe,B)Qs,B).
// first, compute XeB = avf(XeB)
avf1(bnXeB, bnN);
// QsB := [XeB]QsB
BnPointMult(pQsB, pQsB, bnXeB, NULL, NULL, E);
BnEccAdd(pQeB, pQeB, pQsB, E);
// QeB := [tA]QeB = [tA](QsB + [Xe,B]QeB) and check for at infinity
// If the result is not the point at infinity, return QeB
BnPointMult(pQeB, pQeB, bnTa, NULL, NULL, E);
if(BnEqualZero(pQeB->z))
ERROR_RETURN(TPM_RC_NO_RESULT);
// Convert BIGNUM E to TPM2B E
BnPointTo2B(outZ, pQeB, E);
Exit:
CURVE_FREE(E);
return retVal;
}
#endif // ALG_ECMQV
/* 10.2.11.1.3 C_2_2_ECDH() */
/* This function performs the two phase key exchange defined in SP800-56A, 6.1.1.2 Full Unified
Model, C(2, 2, ECC CDH). */
static TPM_RC
C_2_2_ECDH(
TPMS_ECC_POINT *outZs, // OUT: Zs
TPMS_ECC_POINT *outZe, // OUT: Ze
TPM_ECC_CURVE curveId, // IN: the curve for the computations
TPM2B_ECC_PARAMETER *dsA, // IN: static private TPM key
TPM2B_ECC_PARAMETER *deA, // IN: ephemeral private TPM key
TPMS_ECC_POINT *QsB, // IN: static public party B key
TPMS_ECC_POINT *QeB // IN: ephemeral public party B key
)
{
CURVE_INITIALIZED(E, curveId);
ECC_INITIALIZED(bnAs, dsA);
ECC_INITIALIZED(bnAe, deA);
POINT_INITIALIZED(ecBs, QsB);
POINT_INITIALIZED(ecBe, QeB);
POINT(ecZ);
TPM_RC retVal;
//
// Parameter checks
if(E == NULL)
ERROR_RETURN(TPM_RC_CURVE);
pAssert(outZs != NULL && dsA != NULL && deA != NULL && QsB != NULL
&& QeB != NULL);
// Do the point multiply for the Zs value ([dsA]QsB)
retVal = BnPointMult(ecZ, ecBs, bnAs, NULL, NULL, E);
if(retVal == TPM_RC_SUCCESS)
{
// Convert the Zs value.
BnPointTo2B(outZs, ecZ, E);
// Do the point multiply for the Ze value ([deA]QeB)
retVal = BnPointMult(ecZ, ecBe, bnAe, NULL, NULL, E);
if(retVal == TPM_RC_SUCCESS)
BnPointTo2B(outZe, ecZ, E);
}
Exit:
CURVE_FREE(E);
return retVal;
}
/* 10.2.11.1.4 CryptEcc2PhaseKeyExchange() */
/* This function is the dispatch routine for the EC key exchange functions that use two ephemeral
and two static keys. */
/* Error Returns Meaning */
/* TPM_RC_SCHEME scheme is not defined */
LIB_EXPORT TPM_RC
CryptEcc2PhaseKeyExchange(
TPMS_ECC_POINT *outZ1, // OUT: a computed point
TPMS_ECC_POINT *outZ2, // OUT: and optional second point
TPM_ECC_CURVE curveId, // IN: the curve for the computations
TPM_ALG_ID scheme, // IN: the key exchange scheme
TPM2B_ECC_PARAMETER *dsA, // IN: static private TPM key
TPM2B_ECC_PARAMETER *deA, // IN: ephemeral private TPM key
TPMS_ECC_POINT *QsB, // IN: static public party B key
TPMS_ECC_POINT *QeB // IN: ephemeral public party B key
)
{
pAssert(outZ1 != NULL
&& dsA != NULL && deA != NULL
&& QsB != NULL && QeB != NULL);
// Initialize the output points so that they are empty until one of the
// functions decides otherwise
outZ1->x.b.size = 0;
outZ1->y.b.size = 0;
if(outZ2 != NULL)
{
outZ2->x.b.size = 0;
outZ2->y.b.size = 0;
}
switch(scheme)
{
case ALG_ECDH_VALUE:
return C_2_2_ECDH(outZ1, outZ2, curveId, dsA, deA, QsB, QeB);
break;
#if ALG_ECMQV
case ALG_ECMQV_VALUE:
return C_2_2_MQV(outZ1, curveId, dsA, deA, QsB, QeB);
break;
#endif
#if ALG_SM2
case ALG_SM2_VALUE:
return SM2KeyExchange(outZ1, curveId, dsA, deA, QsB, QeB);
break;
#endif
default:
return TPM_RC_SCHEME;
}
}
#if ALG_SM2
/* 10.2.11.1.5 ComputeWForSM2() */
/* Compute the value for w used by SM2 */
static UINT32
ComputeWForSM2(
bigCurve E
)
{
// w := ceil(ceil(log2(n)) / 2) - 1
return (BnMsb(CurveGetOrder(AccessCurveData(E))) / 2 - 1);
}
/* 10.2.11.1.6 avfSm2() */
/* This function does the associated value computation required by SM2 key exchange. This is
different form the avf() in the international standards because it returns a value that is half
the size of the value returned by the standard avf. For example, if n is 15, Ws (w in the
standard) is 2 but the W here is 1. This means that an input value of 14 (1110b) would return a
value of 110b with the standard but 10b with the scheme in SM2. */
static bigNum
avfSm2(
bigNum bn, // IN/OUT: the reduced value
UINT32 w // IN: the value of w
)
{
// a) set w := ceil(ceil(log2(n)) / 2) - 1
// b) set x' := 2^w + ( x & (2^w - 1))
// This is just like the avf for MQV where x' = 2^w + (x mod 2^w)
BnMaskBits(bn, w); // as with avf1, this is too big by a factor of 2 but
// it doesn't matter because we SET the extra bit
// anyway
BnSetBit(bn, w);
return bn;
}
/* SM2KeyExchange() This function performs the key exchange defined in SM2. The first step is to
compute tA = (dsA + deA avf(Xe,A)) mod n Then, compute the Z value from outZ = (h tA mod n) (QsA
+ [avf(QeB().x)](QeB())). The function will compute the ephemeral public key from the ephemeral
private key. All points are required to be on the curve of inQsA. The function will fail
catastrophically if this is not the case */
/* Error Returns Meaning */
/* TPM_RC_NO_RESULT the value for dsA does not give a valid point on the curve */
LIB_EXPORT TPM_RC
SM2KeyExchange(
TPMS_ECC_POINT *outZ, // OUT: the computed point
TPM_ECC_CURVE curveId, // IN: the curve for the computations
TPM2B_ECC_PARAMETER *dsAIn, // IN: static private TPM key
TPM2B_ECC_PARAMETER *deAIn, // IN: ephemeral private TPM key
TPMS_ECC_POINT *QsBIn, // IN: static public party B key
TPMS_ECC_POINT *QeBIn // IN: ephemeral public party B key
)
{
CURVE_INITIALIZED(E, curveId);
const ECC_CURVE_DATA *C;
ECC_INITIALIZED(dsA, dsAIn);
ECC_INITIALIZED(deA, deAIn);
POINT_INITIALIZED(QsB, QsBIn);
POINT_INITIALIZED(QeB, QeBIn);
BN_WORD_INITIALIZED(One, 1);
POINT(QeA);
ECC_NUM(XeB);
POINT(Z);
ECC_NUM(Ta);
UINT32 w;
TPM_RC retVal = TPM_RC_NO_RESULT;
//
// Parameter checks
if(E == NULL)
ERROR_RETURN(TPM_RC_CURVE);
C = AccessCurveData(E);
pAssert(outZ != NULL && dsA != NULL && deA != NULL && QsB != NULL
&& QeB != NULL);
// Compute the value for w
w = ComputeWForSM2(E);
// Compute the public ephemeral key pQeA = [de,A]G
if(!BnEccModMult(QeA, CurveGetG(C), deA, E))
goto Exit;
// tA := (ds,A + de,A avf(Xe,A)) mod n (3)
// Compute 'tA' = ('dsA' + 'deA' avf('XeA')) mod n
// Ta = avf(XeA);
// do Ta = de,A * Ta = deA * avf(XeA)
BnMult(Ta, deA, avfSm2(QeA->x, w));
// now Ta = dsA + Ta = dsA + deA * avf(XeA)
BnAdd(Ta, dsA, Ta);
BnMod(Ta, CurveGetOrder(C));
// outZ = [h tA mod n] (Qs,B + [avf(Xe,B)](Qe,B)) (4)
// Put this in because almost every case of h is == 1 so skip the call when
// not necessary.
if(!BnEqualWord(CurveGetCofactor(C), 1))
// Cofactor is not 1 so compute Ta := Ta * h mod n
BnModMult(Ta, Ta, CurveGetCofactor(C), CurveGetOrder(C));
// Now that 'tA' is (h * 'tA' mod n)
// 'outZ' = ['tA'](QsB + [avf(QeB.x)](QeB)).
BnCopy(XeB, QeB->x);
if(!BnEccModMult2(Z, QsB, One, QeB, avfSm2(XeB, w), E))
goto Exit;
// QeB := [tA]QeB = [tA](QsB + [Xe,B]QeB) and check for at infinity
if(!BnEccModMult(Z, Z, Ta, E))
goto Exit;
// Convert BIGNUM E to TPM2B E
BnPointTo2B(outZ, Z, E);
retVal = TPM_RC_SUCCESS;
Exit:
CURVE_FREE(E);
return retVal;
}
#endif
#endif // CC_ZGen_2Phase
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