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tpm2: Use new privateExponent struct in RsaPrivateKeyOp

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Pass the new privateExponent to RsaPrivateKeyOp replacing the P parameter.
To be able to use MakePgreaterThanQ(Z), make sure that both callers of
this function have Z->P and Z->Q values properly set.

This function has the following two callers:
- CryptRsaPrivateKey: Z->P and Z->Q are already holding valid values
- RSADP: Copy the value of privateExponent.Q to Z->Q.

An inconsequential side effect of the changes to RsaPrivateKeyOp()
is that Z->P is greater than Z->Q upon return from this function.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
This commit is contained in:
Stefan Berger 2023-08-28 09:51:10 -04:00 committed by Stefan Berger
parent 7edfb28a2e
commit c9a0650e52
1 changed files with 10 additions and 19 deletions
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29
src/tpm2/crypto/openssl/CryptRsa.c
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@ -233,7 +233,7 @@ ComputePrivateExponent(
static BOOL
RsaPrivateKeyOp(
bigNum inOut, // IN/OUT: number to be exponentiated
bigNum P, // IN: one of the primes (can be NULL if not CRT)
privateExponent *Z,
privateExponent_t *pExp
)
{
@ -242,28 +242,18 @@ RsaPrivateKeyOp(
BN_RSA(M);
BN_RSA(H);
//
bigNum Q = (bigNum)&pExp->Q;
// Make P the larger prime.
// NOTE that when the CRT form of the private key is created, dP will always
// be computed using the larger of p and q so the only thing needed here is that
// the primes be selected so that they agree with dP.
if(BnUnsignedCmp(P, Q) < 0)
{
bigNum T = P;
P = Q;
Q = T;
}
MakePgreaterThanQ(Z);
// m1 = cdP mod p
VERIFY(BnModExp(M1, inOut, (bigNum)&pExp->dP, P));
VERIFY(BnModExp(M1, inOut, (bigNum)&pExp->dP, Z->P));
// m2 = cdQ mod q
VERIFY(BnModExp(M2, inOut, (bigNum)&pExp->dQ, Q));
VERIFY(BnModExp(M2, inOut, (bigNum)&pExp->dQ, Z->Q));
// h = qInv * (m1 - m2) mod p = qInv * (m1 + P - m2) mod P because Q < P
// so m2 < P
VERIFY(BnSub(H, P, M2));
VERIFY(BnSub(H, Z->P, M2));
VERIFY(BnAdd(H, H, M1));
VERIFY(BnModMult(H, H, (bigNum)&pExp->qInv, P));
VERIFY(BnModMult(H, H, (bigNum)&pExp->qInv, Z->P));
// m = m2 + h * q
VERIFY(BnMult(M, H, Q));
VERIFY(BnMult(M, H, Z->Q));
VERIFY(BnAdd(inOut, M2, M));
return TRUE;
Error:
@ -335,7 +325,8 @@ RSADP(
return TPM_RC_BINDING;
}
VERIFY(BnFrom2B(Z->P, &key->sensitive.sensitive.rsa.b) != NULL);
VERIFY(RsaPrivateKeyOp(bnM, Z->P, &key->privateExponent));
BnCopy(Z->Q, (bigNum)&key->privateExponent.Q);
VERIFY(RsaPrivateKeyOp(bnM, Z, &key->privateExponent));
VERIFY(BnTo2B(bnM, inOut, inOut->size));
return TPM_RC_SUCCESS;
Error:
@ -1403,7 +1394,7 @@ CryptRsaGenerateKey(
// Encrypt with public exponent...
BnModExp(temp2, temp1, bnPubExp, bnN);
// ... then decrypt with private exponent
RsaPrivateKeyOp(temp2, Z->P, &rsaKey->privateExponent);
RsaPrivateKeyOp(temp2, Z, &rsaKey->privateExponent);
// If the starting and ending values are not the same,
// start over )-;
if(BnUnsignedCmp(temp2, temp1) != 0)