csu3_am335x/EVSE/GPL/ibmtpm1682/src/CryptEccCrypt.c

/********************************************************************************/
/*										*/
/*			  Asymmetric ECC Commands   				*/
/*			     Written by Ken Goldman				*/
/*		       IBM Thomas J. Watson Research Center			*/
/*            $Id$	*/
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/********************************************************************************/


/* 10.2.28.1	Includes and Defines */
#include "Tpm.h"

#if CC_ECC_Encrypt || CC_ECC_Encrypt
/* 10.2.28.2	Functions */
/* 10.2.28.2.1	CryptEccSelectScheme() */
/* This function is used by TPM2_ECC_Decrypt and TPM2_ECC_Encrypt.  It sets scheme either the input
   scheme or the key scheme. If they key scheme is not TPM_ALG_NULL then the input scheme must be
   TPM_ALG_NULL or the same as the key scheme. If not, then the function returns FALSE. */
/*     Return Value	Meaning */
/*     TRUE	scheme is set */
/*     FALSE	scheme is not valid (it may have been changed). */
BOOL
CryptEccSelectScheme(
		     OBJECT              *key,           //IN: key containing default scheme
		     TPMT_KDF_SCHEME     *scheme         // IN: a decrypt scheme
		     )
{
    TPMT_KDF_SCHEME    *keyScheme = &key->publicArea.parameters.eccDetail.kdf;

    // Get sign object pointer
    if(scheme->scheme == TPM_ALG_NULL)
	*scheme = *keyScheme;
    if(keyScheme->scheme == TPM_ALG_NULL)
	keyScheme = scheme;
    return (scheme->scheme != TPM_ALG_NULL &&
	    (keyScheme->scheme == scheme->scheme
	     && keyScheme->details.anyKdf.hashAlg == scheme->details.anyKdf.hashAlg));
}
/* 10.2.28.2.2	CryptEccEncrypt() */
/* This function performs ECC-based data obfuscation. The only scheme that is currently supported is
   MGF1 based. See Part 1, Annex D for details. */
/*     Error Return	Meaning */
/*     TPM_RC_CURVE	unsupported curve */
/*     TPM_RC_HASH	hash not allowed */
/*     TPM_RC_SCHEME	scheme is not supported */
/*     TPM_RC_NO_RESULT	internal error in big number processing */
LIB_EXPORT TPM_RC
CryptEccEncrypt(
		OBJECT                  *key,           // IN: public key of recipient
		TPMT_KDF_SCHEME         *scheme,        // IN: scheme to use.
		TPM2B_MAX_BUFFER        *plainText,     // IN: the text to obfuscate
		TPMS_ECC_POINT          *c1,            // OUT: public ephemeral key
		TPM2B_MAX_BUFFER        *c2,            // OUT: obfuscated text
		TPM2B_DIGEST            *c3             // OUT: digest of ephemeral key
		//      and plainText
		)
{
    CURVE_INITIALIZED(E, key->publicArea.parameters.eccDetail.curveID);
    POINT_INITIALIZED(PB, &key->publicArea.unique.ecc);
    POINT_VAR(Px, MAX_ECC_KEY_BITS);
    TPMS_ECC_POINT          p2;
    ECC_NUM(D);
    TPM2B_TYPE(2ECC, MAX_ECC_KEY_BYTES * 2);
    TPM2B_2ECC              z;
    int                     i;
    HASH_STATE              hashState;
    TPM_RC                  retVal = TPM_RC_SUCCESS;
    //
#if defined DEBUG_ECC_ENCRYPT && DEBUG_ECC_ENCRYPT == YES
    RND_DEBUG           dbg;
    // This value is one less than the value from the reference so that it
    // will become the correct value after having one added
    TPM2B_ECC_PARAMETER k = {24, {
	    0x38, 0x4F, 0x30, 0x35, 0x30, 0x73, 0xAE, 0xEC,
	    0xE7, 0xA1, 0x65, 0x43, 0x30, 0xA9, 0x62, 0x04,
	    0xD3, 0x79, 0x82, 0xA3, 0xE1, 0x5B, 0x2C, 0xB4}};
    RND_DEBUG_Instantiate(&dbg, &k.b);
#   define RANDOM      (RAND_STATE *)&dbg

#else
#   define RANDOM      NULL
#endif
    if (E == NULL)
	ERROR_RETURN(TPM_RC_CURVE);
    if (TPM_ALG_KDF2 != scheme->scheme)
	ERROR_RETURN(TPM_RC_SCHEME);
    // generate an ephemeral key from a random k
    if (!BnEccGenerateKeyPair(D, Px, E, RANDOM)
	// C1 is the public part of the ephemeral key
	|| !BnPointTo2B(c1, Px, E)
	// Compute P2
	|| (BnPointMult(Px, PB, D, NULL, NULL, E) != TPM_RC_SUCCESS)
	|| !BnPointTo2B(&p2, Px, E))
	ERROR_RETURN(TPM_RC_NO_RESULT);

    //Compute the C3 value hash(x2 || M || y2)
    if (0 == CryptHashStart(&hashState, scheme->details.mgf1.hashAlg))
	ERROR_RETURN(TPM_RC_HASH);
    CryptDigestUpdate2B(&hashState, &p2.x.b);
    CryptDigestUpdate2B(&hashState, &plainText->b);
    CryptDigestUpdate2B(&hashState, &p2.y.b);
    c3->t.size = CryptHashEnd(&hashState, sizeof(c3->t.buffer), c3->t.buffer);

    MemoryCopy2B(&z.b, &p2.x.b, sizeof(z.t.buffer));
    MemoryConcat2B(&z.b, &p2.y.b, sizeof(z.t.buffer));
    // Generate the mask value from MGF1 and put it in the return buffer
    c2->t.size = CryptMGF_KDF(plainText->t.size, c2->t.buffer,
			      scheme->details.mgf1.hashAlg, z.t.size, z.t.buffer, 1);
    // XOR the plainText into the generated mask to create the obfuscated data
    for (i = 0; i < plainText->t.size; i++)
	c2->t.buffer[i] ^= plainText->t.buffer[i];
 Exit:
    CURVE_FREE(E);
    return retVal;
}
/* 10.2.28.2.3	CryptEccDecrypt() */
/* This function performs ECC decryption and integrity check of the input data. */
/* Error Return	Meaning */
/* TPM_RC_CURVE	unsupported curve */
/* TPM_RC_HASH	hash not allowed */
/* TPM_RC_SCHEME	scheme is not supported */
/* TPM_RC_NO_RESULT	internal error in big number processing */
/* TPM_RC_VALUE	C3 did not match hash of recovered data */
LIB_EXPORT TPM_RC
CryptEccDecrypt(
		OBJECT                  *key,           // IN: key used for data recovery
		TPMT_KDF_SCHEME         *scheme,        // IN: scheme to use.
		TPM2B_MAX_BUFFER        *plainText,     // OUT: the recovered text
		TPMS_ECC_POINT          *c1,            // IN: public ephemeral key
		TPM2B_MAX_BUFFER        *c2,            // IN: obfuscated text
		TPM2B_DIGEST            *c3             // IN: digest of ephemeral key
		//      and plainText
		)
{
    CURVE_INITIALIZED(E, key->publicArea.parameters.eccDetail.curveID);
    ECC_INITIALIZED(D, &key->sensitive.sensitive.ecc.b);
    POINT_INITIALIZED(C1, c1);
    TPMS_ECC_POINT          p2;
    TPM2B_TYPE(2ECC, MAX_ECC_KEY_BYTES * 2);
    TPM2B_DIGEST            check;
    TPM2B_2ECC              z;
    int                     i;
    HASH_STATE              hashState;
    TPM_RC                  retVal = TPM_RC_SUCCESS;
    //
    if (E == NULL)
	ERROR_RETURN(TPM_RC_CURVE);
    if (TPM_ALG_KDF2 != scheme->scheme)
	ERROR_RETURN(TPM_RC_SCHEME);
    // Generate the Z value
    BnPointMult(C1, C1, D, NULL, NULL, E);
    BnPointTo2B(&p2, C1, E);

    // Start the hash to check the algorithm
    if (0 == CryptHashStart(&hashState, scheme->details.mgf1.hashAlg))
	ERROR_RETURN(TPM_RC_HASH);
    CryptDigestUpdate2B(&hashState, &p2.x.b);

    MemoryCopy2B(&z.b, &p2.x.b, sizeof(z.t.buffer));
    MemoryConcat2B(&z.b, &p2.y.b, sizeof(z.t.buffer));

    // Generate the mask
    plainText->t.size = CryptMGF_KDF(c2->t.size, plainText->t.buffer,
				     scheme->details.mgf1.hashAlg, z.t.size,
				     z.t.buffer, 1);
    // XOR the obfuscated data into the generated mask to create the plainText data
    for (i = 0; i < plainText->t.size; i++)
	plainText->t.buffer[i] ^= c2->t.buffer[i];

    // Complete the hash and verify the data
    CryptDigestUpdate2B(&hashState, &plainText->b);
    CryptDigestUpdate2B(&hashState, &p2.y.b);
    check.t.size = CryptHashEnd(&hashState, sizeof(check.t.buffer), check.t.buffer);
    if (!MemoryEqual2B(&check.b, &c3->b))
	ERROR_RETURN(TPM_RC_VALUE);
 Exit:
    CURVE_FREE(E);
    return retVal;
}
#endif  // CC_ECC_Encrypt ||