--- a/sys/crypto/cryptoapi/cryptoapi.c
+++ b/sys/crypto/cryptoapi/cryptoapi.c
@@ -370,7 +370,6 @@
 struct aes_xts_ctx {
 	rijndael_ctx key1;
 	rijndael_ctx key2;
-	uint8_t tweak[AES_XTS_BLOCK_LEN];
 };
 
 static bool
@@ -410,7 +409,8 @@
 }
 
 static inline void
-aes_xts_reinit(struct aes_xts_ctx *ctx, const uint8_t *iv)
+aes_xts_reinit(struct aes_xts_ctx *ctx, uint8_t tweak[AES_XTS_BLOCK_LEN],
+    const uint8_t *iv)
 {
 #if 0
 	/*
@@ -419,12 +419,12 @@
 	 */
 	/* XXX: possibly use htole64? */
 #endif
-	memcpy(ctx->tweak, iv, AES_XTS_IV_LEN);
+	memcpy(tweak, iv, AES_XTS_IV_LEN);
 
 	/* Last 64 bits of IV are always zero */
-	bzero(ctx->tweak + AES_XTS_IV_LEN, AES_XTS_IV_LEN);
+	bzero(tweak + AES_XTS_IV_LEN, AES_XTS_IV_LEN);
 
-	rijndael_encrypt(&ctx->key2, ctx->tweak, ctx->tweak);
+	rijndael_encrypt(&ctx->key2, tweak, tweak);
 }
 
 static void
@@ -432,13 +432,16 @@
     bool encrypt)
 {
 	uint8_t block[AES_XTS_BLOCK_LEN];
+	uint8_t tweak[AES_XTS_BLOCK_LEN];
 	struct aes_xts_ctx *ctx = _ctx;
 
-	aes_xts_reinit(ctx, iv);
+	aes_xts_reinit(ctx, tweak, iv);
 
-	crypt_data_xts(&ctx->key1, data, datalen, ctx->tweak,
+	crypt_data_xts(&ctx->key1, data, datalen, tweak,
 	    encrypt ? rijndael_encrypt_wrap : rijndael_decrypt_wrap, block,
 	    AES_XTS_BLOCK_LEN, AES_XTS_ALPHA);
+
+	explicit_bzero(tweak, sizeof(tweak));
 }
 
 const struct cryptoapi_cipher_spec cipher_aes_xts = {
@@ -725,11 +728,11 @@
 struct twofish_xts_ctx {
 	twofish_ctx key1;
 	twofish_ctx key2;
-	uint8_t tweak[TWOFISH_XTS_BLOCK_LEN];
 };
 
 static inline void
-twofish_xts_reinit(struct twofish_xts_ctx *ctx, const uint8_t *iv)
+twofish_xts_reinit(struct twofish_xts_ctx *ctx,
+    uint8_t tweak[TWOFISH_XTS_BLOCK_LEN], const uint8_t *iv)
 {
 #if 0
 	u_int64_t blocknum;
@@ -742,12 +745,12 @@
 	 */
 	/* XXX: possibly use htole64? */
 #endif
-	memcpy(ctx->tweak, iv, TWOFISH_XTS_IV_LEN);
+	memcpy(tweak, iv, TWOFISH_XTS_IV_LEN);
 
 	/* Last 64 bits of IV are always zero */
-	bzero(ctx->tweak + TWOFISH_XTS_IV_LEN, TWOFISH_XTS_IV_LEN);
+	bzero(tweak + TWOFISH_XTS_IV_LEN, TWOFISH_XTS_IV_LEN);
 
-	twofish_encrypt(&ctx->key2, ctx->tweak, ctx->tweak);
+	twofish_encrypt(&ctx->key2, tweak, tweak);
 }
 
 static int
@@ -782,13 +785,16 @@
     bool encrypt)
 {
 	uint8_t block[TWOFISH_XTS_BLOCK_LEN];
+	uint8_t tweak[TWOFISH_XTS_BLOCK_LEN];
 	struct twofish_xts_ctx *ctx = _ctx;
 
-	twofish_xts_reinit(ctx, iv);
+	twofish_xts_reinit(ctx, tweak, iv);
 
-	crypt_data_xts(&ctx->key1, data, datalen, ctx->tweak,
+	crypt_data_xts(&ctx->key1, data, datalen, tweak,
 	    encrypt ? twofish_encrypt_wrap : twofish_decrypt_wrap, block,
 	    TWOFISH_XTS_BLOCK_LEN, AES_XTS_ALPHA);
+
+	explicit_bzero(tweak, sizeof(tweak));
 }
 
 const struct cryptoapi_cipher_spec cipher_twofish_xts = {
@@ -888,11 +894,11 @@
 struct serpent_xts_ctx {
 	serpent_ctx key1;
 	serpent_ctx key2;
-	uint8_t tweak[SERPENT_XTS_BLOCK_LEN];
 };
 
 static inline void
-serpent_xts_reinit(struct serpent_xts_ctx *ctx, const uint8_t *iv)
+serpent_xts_reinit(struct serpent_xts_ctx *ctx,
+    uint8_t tweak[SERPENT_XTS_BLOCK_LEN], const uint8_t *iv)
 {
 #if 0
 	u_int64_t blocknum;
@@ -907,12 +913,12 @@
 	/* XXX: possibly use htole64? */
 #endif
 
-	memcpy(ctx->tweak, iv, SERPENT_XTS_IV_LEN);
+	memcpy(tweak, iv, SERPENT_XTS_IV_LEN);
 
 	/* Last 64 bits of IV are always zero */
-	bzero(ctx->tweak + SERPENT_XTS_IV_LEN, SERPENT_XTS_IV_LEN);
+	bzero(tweak + SERPENT_XTS_IV_LEN, SERPENT_XTS_IV_LEN);
 
-	serpent_encrypt(&ctx->key2, ctx->tweak, ctx->tweak);
+	serpent_encrypt(&ctx->key2, tweak, tweak);
 }
 
 static int
@@ -947,13 +953,16 @@
     bool encrypt)
 {
 	uint8_t block[SERPENT_XTS_BLOCK_LEN];
+	uint8_t tweak[SERPENT_XTS_BLOCK_LEN];
 	struct serpent_xts_ctx *ctx = _ctx;
 
-	serpent_xts_reinit(ctx, iv);
+	serpent_xts_reinit(ctx, tweak, iv);
 
-	crypt_data_xts(&ctx->key1, data, datalen, ctx->tweak,
+	crypt_data_xts(&ctx->key1, data, datalen, tweak,
 	    encrypt ? serpent_encrypt_wrap : serpent_decrypt_wrap, block,
 	    SERPENT_XTS_BLOCK_LEN, AES_XTS_ALPHA);
+
+	explicit_bzero(tweak, sizeof(tweak));
 }
 
 const struct cryptoapi_cipher_spec cipher_serpent_xts = {