diff --git a/include/gmssl/sm4.h b/include/gmssl/sm4.h
index 18b17475..c21d4483 100644
--- a/include/gmssl/sm4.h
+++ b/include/gmssl/sm4.h
@@ -35,9 +35,9 @@ void sm4_set_decrypt_key(SM4_KEY *key, const uint8_t raw_key[SM4_KEY_SIZE]);
 void sm4_encrypt(const SM4_KEY *key, const uint8_t in[SM4_BLOCK_SIZE], uint8_t out[SM4_BLOCK_SIZE]);
 
 void sm4_encrypt_blocks(const SM4_KEY *key, const uint8_t *in, size_t nblocks, uint8_t *out);
-void sm4_cbc_encrypt_blocks(const SM4_KEY *key, const uint8_t iv[SM4_BLOCK_SIZE],
+void sm4_cbc_encrypt_blocks(const SM4_KEY *key, uint8_t iv[SM4_BLOCK_SIZE],
 	const uint8_t *in, size_t nblocks, uint8_t *out);
-void sm4_cbc_decrypt_blocks(const SM4_KEY *key, const uint8_t iv[SM4_BLOCK_SIZE],
+void sm4_cbc_decrypt_blocks(const SM4_KEY *key, uint8_t iv[SM4_BLOCK_SIZE],
 	const uint8_t *in, size_t nblocks, uint8_t *out);
 void sm4_ctr_encrypt_blocks(const SM4_KEY *key, uint8_t ctr[16], const uint8_t *in, size_t nblocks, uint8_t *out);
 void sm4_ctr32_encrypt_blocks(const SM4_KEY *key, uint8_t ctr[16], const uint8_t *in, size_t nblocks, uint8_t *out);
diff --git a/src/sm4.c b/src/sm4.c
index d26a6e73..472b7807 100644
--- a/src/sm4.c
+++ b/src/sm4.c
@@ -168,34 +168,42 @@ void sm4_encrypt_blocks(const SM4_KEY *key, const uint8_t *in, size_t nblocks, u
 	}
 }
 
-void sm4_cbc_encrypt_blocks(const SM4_KEY *key, const uint8_t iv[16],
+void sm4_cbc_encrypt_blocks(const SM4_KEY *key, uint8_t iv[16],
 	const uint8_t *in, size_t nblocks, uint8_t *out)
 {
+	uint8_t *piv = iv;
+
 	while (nblocks--) {
 		size_t i;
 		for (i = 0; i < 16; i++) {
-			out[i] = in[i] ^ iv[i];
+			out[i] = in[i] ^ piv[i];
 		}
 		sm4_encrypt(key, out, out);
-		iv = out;
+		piv = out;
 		in += 16;
 		out += 16;
 	}
+
+	memcpy(iv, piv, 16);
 }
 
-void sm4_cbc_decrypt_blocks(const SM4_KEY *key, const uint8_t iv[16],
+void sm4_cbc_decrypt_blocks(const SM4_KEY *key, uint8_t iv[16],
 	const uint8_t *in, size_t nblocks, uint8_t *out)
 {
+	uint8_t *piv = iv;
+
 	while (nblocks--) {
 		size_t i;
 		sm4_encrypt(key, in, out);
 		for (i = 0; i < 16; i++) {
-			out[i] ^= iv[i];
+			out[i] ^= piv[i];
 		}
-		iv = in;
+		piv = in;
 		in += 16;
 		out += 16;
 	}
+
+	memcpy(iv, piv, 16);
 }
 
 static void ctr_incr(uint8_t a[16]) {
@@ -630,7 +638,7 @@ void sm4_encrypt_blocks(const SM4_KEY *key, const uint8_t *in, size_t nblocks, u
 	}
 }
 
-void sm4_cbc_encrypt_blocks(const SM4_KEY *key, const uint8_t iv[16], const uint8_t *in, size_t nblocks, uint8_t *out)
+void sm4_cbc_encrypt_blocks(const SM4_KEY *key, uint8_t iv[16], const uint8_t *in, size_t nblocks, uint8_t *out)
 {
 	const uint32_t *rk = key->rk;
 	uint32_t X0, X1, X2, X3, X4;
@@ -690,9 +698,14 @@ void sm4_cbc_encrypt_blocks(const SM4_KEY *key, const uint8_t iv[16], const uint
 		in += 16;
 		out += 16;
 	}
+
+	PUTU32(iv     , X0);
+	PUTU32(iv +  4, X4);
+	PUTU32(iv +  8, X3);
+	PUTU32(iv + 12, X2);
 }
 
-void sm4_cbc_decrypt_blocks(const SM4_KEY *key, const uint8_t iv[16], const uint8_t *in, size_t nblocks, uint8_t *out)
+void sm4_cbc_decrypt_blocks(const SM4_KEY *key, uint8_t iv[16], const uint8_t *in, size_t nblocks, uint8_t *out)
 {
 	const uint32_t *rk = key->rk;
 	uint32_t IV0, IV1, IV2, IV3;
@@ -756,6 +769,11 @@ void sm4_cbc_decrypt_blocks(const SM4_KEY *key, const uint8_t iv[16], const uint
 		in += 16;
 		out += 16;
 	}
+
+	PUTU32(iv     , IV0);
+	PUTU32(iv +  4, IV1);
+	PUTU32(iv +  8, IV2);
+	PUTU32(iv + 12, IV3);
 }
 
 void sm4_ctr_encrypt_blocks(const SM4_KEY *key, uint8_t ctr[16], const uint8_t *in, size_t nblocks, uint8_t *out)
diff --git a/src/sm4_cbc.c b/src/sm4_cbc.c
index 95e5e565..2349153c 100644
--- a/src/sm4_cbc.c
+++ b/src/sm4_cbc.c
@@ -13,36 +13,42 @@
 #include <gmssl/error.h>
 
 
-int sm4_cbc_padding_encrypt(const SM4_KEY *key, const uint8_t iv[16],
+int sm4_cbc_padding_encrypt(const SM4_KEY *key, const uint8_t piv[16],
 	const uint8_t *in, size_t inlen,
 	uint8_t *out, size_t *outlen)
 {
+	uint8_t iv[16];
 	uint8_t block[16];
 	size_t rem = inlen % 16;
 	int padding = 16 - inlen % 16;
 
+	memcpy(iv, piv, 16);
+
 	if (in) {
 		memcpy(block, in + inlen - rem, rem);
 	}
 	memset(block + rem, padding, padding);
+
 	if (inlen/16) {
 		sm4_cbc_encrypt_blocks(key, iv, in, inlen/16, out);
 		out += inlen - rem;
-		iv = out - 16;
 	}
 	sm4_cbc_encrypt_blocks(key, iv, block, 1, out);
 	*outlen = inlen - rem + 16;
 	return 1;
 }
 
-int sm4_cbc_padding_decrypt(const SM4_KEY *key, const uint8_t iv[16],
+int sm4_cbc_padding_decrypt(const SM4_KEY *key, const uint8_t piv[16],
 	const uint8_t *in, size_t inlen,
 	uint8_t *out, size_t *outlen)
 {
+	uint8_t iv[16];
 	uint8_t block[16];
 	size_t len = sizeof(block);
 	int padding;
 
+	memcpy(iv, piv, 16);
+
 	if (inlen == 0) {
 		error_puts("warning: input lenght = 0");
 		return 0;
@@ -53,8 +59,8 @@ int sm4_cbc_padding_decrypt(const SM4_KEY *key, const uint8_t iv[16],
 	}
 	if (inlen > 16) {
 		sm4_cbc_decrypt_blocks(key, iv, in, inlen/16 - 1, out);
-		iv = in + inlen - 32;
 	}
+
 	sm4_cbc_decrypt_blocks(key, iv, in + inlen - 16, 1, block);
 
 	padding = block[15];
@@ -111,7 +117,7 @@ int sm4_cbc_encrypt_update(SM4_CBC_CTX *ctx,
 		}
 		memcpy(ctx->block + ctx->block_nbytes, in, left);
 		sm4_cbc_encrypt_blocks(&ctx->sm4_key, ctx->iv, ctx->block, 1, out);
-		memcpy(ctx->iv, out, SM4_BLOCK_SIZE);
+		//memcpy(ctx->iv, out, SM4_BLOCK_SIZE);
 		in += left;
 		inlen -= left;
 		out += SM4_BLOCK_SIZE;
@@ -121,7 +127,7 @@ int sm4_cbc_encrypt_update(SM4_CBC_CTX *ctx,
 		nblocks = inlen / SM4_BLOCK_SIZE;
 		len = nblocks * SM4_BLOCK_SIZE;
 		sm4_cbc_encrypt_blocks(&ctx->sm4_key, ctx->iv, in, nblocks, out);
-		memcpy(ctx->iv, out + len - SM4_BLOCK_SIZE, SM4_BLOCK_SIZE);
+		//memcpy(ctx->iv, out + len - SM4_BLOCK_SIZE, SM4_BLOCK_SIZE);
 		in += len;
 		inlen -= len;
 		out += len;
@@ -197,7 +203,6 @@ int sm4_cbc_decrypt_update(SM4_CBC_CTX *ctx,
 		}
 		memcpy(ctx->block + ctx->block_nbytes, in, left);
 		sm4_cbc_decrypt_blocks(&ctx->sm4_key, ctx->iv, ctx->block, 1, out);
-		memcpy(ctx->iv, ctx->block, SM4_BLOCK_SIZE);
 		in += left;
 		inlen -= left;
 		out += SM4_BLOCK_SIZE;
@@ -207,7 +212,6 @@ int sm4_cbc_decrypt_update(SM4_CBC_CTX *ctx,
 		nblocks = (inlen-1) / SM4_BLOCK_SIZE;
 		len = nblocks * SM4_BLOCK_SIZE;
 		sm4_cbc_decrypt_blocks(&ctx->sm4_key, ctx->iv, in, nblocks, out);
-		memcpy(ctx->iv, in + len - SM4_BLOCK_SIZE, SM4_BLOCK_SIZE);
 		in += len;
 		inlen -= len;
 		out += len;
diff --git a/src/tls.c b/src/tls.c
index 296ef947..b2df6783 100644
--- a/src/tls.c
+++ b/src/tls.c
@@ -326,7 +326,7 @@ int tls_cbc_decrypt(const SM3_HMAC_CTX *inited_hmac_ctx, const SM4_KEY *dec_key,
 	const uint8_t *in, size_t inlen, uint8_t *out, size_t *outlen)
 {
 	SM3_HMAC_CTX hmac_ctx;
-	const uint8_t *iv;
+	uint8_t iv[16];
 	const uint8_t *padding;
 	const uint8_t *mac;
 	uint8_t header[5];
@@ -345,7 +345,7 @@ int tls_cbc_decrypt(const SM3_HMAC_CTX *inited_hmac_ctx, const SM4_KEY *dec_key,
 		return -1;
 	}
 
-	iv = in;
+	memcpy(iv, in, 16);
 	in += 16;
 	inlen -= 16;
 
diff --git a/tests/sm4_cbctest.c b/tests/sm4_cbctest.c
index d657671c..0bd375d5 100644
--- a/tests/sm4_cbctest.c
+++ b/tests/sm4_cbctest.c
@@ -21,15 +21,19 @@
 static int test_sm4_cbc(void)
 {
 	SM4_KEY sm4_key;
-	uint8_t key[16] = {0};
-	uint8_t iv[16] = {0};
+	const uint8_t key[16] = {0};
+	const uint8_t civ[16] = {0};
+	uint8_t iv[16];
 	uint8_t buf1[32] = {0};
 	uint8_t buf2[32] = {0};
 	uint8_t buf3[32] = {0};
 
 	sm4_set_encrypt_key(&sm4_key, key);
+	memcpy(iv, civ, 16);
 	sm4_cbc_encrypt_blocks(&sm4_key, iv, buf1, 2, buf2);
+
 	sm4_set_decrypt_key(&sm4_key, key);
+	memcpy(iv, civ, 16);
 	sm4_cbc_decrypt_blocks(&sm4_key, iv, buf2, 2, buf3);
 
 	if (memcmp(buf1, buf3, sizeof(buf3)) != 0) {
@@ -107,6 +111,7 @@ static int test_sm4_cbc_test_vectors(void)
 		}
 
 		sm4_set_encrypt_key(&sm4_key, key);
+		hex_to_bytes(tests[i].iv, strlen(tests[i].iv), iv, &iv_len);
 		sm4_cbc_encrypt_blocks(&sm4_key, iv, plaintext, plaintext_len/16, encrypted);
 
 		if (memcmp(encrypted, ciphertext, ciphertext_len) != 0) {