tpm2-common: add point conversion routines

Point conversion from openssl to TPM format is now used in a couple of
places in the current code, so move it into the common routines.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

3 files changed, 31 insertions, 19 deletions

diff --git a/e_tpm2-ecc.c b/e_tpm2-ecc.c
index e0b0c47..21a636c 100644
--- a/e_tpm2-ecc.c
+++ b/e_tpm2-ecc.c
@@ -236,26 +236,11 @@ static int tpm2_ecc_compute_key(unsigned char **psec, size_t *pseclen,
 	TPM_SE sessionType;
 	char *auth;
 	size_t len;
-	const EC_GROUP *group;
-	BN_CTX *ctx;
-	unsigned char point[MAX_ECC_KEY_BYTES*2 + 1];
 	int num_commands;
 	struct policy_command *commands;
 	TPM_ALG_ID nameAlg;
 	int ret;
 
-	group = EC_KEY_get0_group(eck);
-	ctx = BN_CTX_new();
-	if (!ctx)
-		return 0;
-	BN_CTX_start(ctx);
-	len = EC_POINT_point2oct(group, pt, POINT_CONVERSION_UNCOMPRESSED,
-				 point, sizeof(point), ctx);
-	BN_CTX_free(ctx);
-
-	len--;
-	len >>= 1;
-
 	in.keyHandle = tpm2_load_key_from_ecc(eck, &tssContext, &auth,
 					      &sessionType, &num_commands,
 					      &commands, &nameAlg);
@@ -263,10 +248,9 @@ static int tpm2_ecc_compute_key(unsigned char **psec, size_t *pseclen,
 		fprintf(stderr, "Failed to get Key Handle in TPM EC key routines\n");
 		return 0;
 	}
-	memcpy(in.inPoint.point.x.t.buffer, point + 1, len);
-	in.inPoint.point.x.t.size = len;
-	memcpy(in.inPoint.point.y.t.buffer, point + 1 + len, len);
-	in.inPoint.point.y.t.size = len;
+	len = tpm2_get_public_point(&in.inPoint, EC_KEY_get0_group(eck), pt);
+	if (!len)
+		return 0;
 
 	ret = 0;
 	rc = tpm2_get_session_handle(tssContext, &authHandle, 0, sessionType,
diff --git a/tpm2-common.c b/tpm2-common.c
index 1b1eead..9d1737b 100644
--- a/tpm2-common.c
+++ b/tpm2-common.c
@@ -1022,3 +1022,29 @@ TPM_RC tpm2_create(TSS_CONTEXT **tsscp, const char *dir)
 
 	return TPM_RC_SUCCESS;
 }
+
+int tpm2_get_public_point(TPM2B_ECC_POINT *tpmpt, const EC_GROUP *group,
+			  const EC_POINT *pt)
+{
+	BN_CTX *ctx;
+	size_t len;
+	unsigned char point[MAX_ECC_KEY_BYTES*2 + 1];
+
+	ctx = BN_CTX_new();
+	if (!ctx)
+		return 0;
+	BN_CTX_start(ctx);
+	len = EC_POINT_point2oct(group, pt, POINT_CONVERSION_UNCOMPRESSED,
+				 point, sizeof(point), ctx);
+	BN_CTX_free(ctx);
+
+	len--;
+	len >>= 1;
+
+	memcpy(tpmpt->point.x.t.buffer, point + 1, len);
+	tpmpt->point.x.t.size = len;
+	memcpy(tpmpt->point.y.t.buffer, point + 1 + len, len);
+	tpmpt->point.y.t.size = len;
+
+	return len;
+}
diff --git a/tpm2-common.h b/tpm2-common.h
index 14aae40..1cf3b23 100644
--- a/tpm2-common.h
+++ b/tpm2-common.h
@@ -42,4 +42,6 @@ TPM_RC tpm2_create(TSS_CONTEXT **tsscp, const char *dir);
 TPM_RC tpm2_readpublic(TSS_CONTEXT *tssContext, TPM_HANDLE handle,
 		       TPMT_PUBLIC *pub);
 void tpm2_rm_tssdir(const char *dir, TPM_HANDLE extrakey);
+int tpm2_get_public_point(TPM2B_ECC_POINT *tpmpt, const EC_GROUP *group,
+			  const EC_POINT *pt);
 #endif