diff --git a/include/sys/crypto/common.h b/include/sys/crypto/common.h
index 76be22952..7db5d87cb 100644
--- a/include/sys/crypto/common.h
+++ b/include/sys/crypto/common.h
@@ -214,19 +214,6 @@ typedef uint32_t crypto_keysize_unit_t;
 #define	SUN_CKM_ECDSA_SHA1		"CKM_ECDSA_SHA1"
 #define	SUN_CKM_ECDSA			"CKM_ECDSA"
 
-/* Shared operation context format for CKM_RC4 */
-typedef struct {
-#if defined(__amd64)
-	uint32_t	i, j;
-	uint32_t	arr[256];
-	uint32_t	flag;
-#else
-	uchar_t		arr[256];
-	uchar_t		i, j;
-#endif /* __amd64 */
-	uint64_t	pad;		/* For 64-bit alignment */
-} arcfour_state_t;
-
 /* Data arguments of cryptographic operations */
 
 typedef enum crypto_data_format {
@@ -238,21 +225,15 @@ typedef struct crypto_data {
 	crypto_data_format_t	cd_format;	/* Format identifier	*/
 	off_t			cd_offset;	/* Offset from the beginning */
 	size_t			cd_length;	/* # of bytes in use */
-	caddr_t			cd_miscdata;	/* ancillary data */
 	union {
 		/* Raw format */
-		iovec_t cdu_raw;		/* Pointer and length	    */
+		iovec_t cd_raw;		/* Pointer and length	    */
 
 		/* uio scatter-gather format */
-		zfs_uio_t	*cdu_uio;
-
-	} cdu;	/* Crypto Data Union */
+		zfs_uio_t	*cd_uio;
+	};	/* Crypto Data Union */
 } crypto_data_t;
 
-#define	cd_raw		cdu.cdu_raw
-#define	cd_uio		cdu.cdu_uio
-#define	cd_mp		cdu.cdu_mp
-
 /* The keys, and their contents */
 
 typedef struct {
diff --git a/module/icp/algs/modes/cbc.c b/module/icp/algs/modes/cbc.c
index bddb5b64d..73605f04d 100644
--- a/module/icp/algs/modes/cbc.c
+++ b/module/icp/algs/modes/cbc.c
@@ -242,19 +242,12 @@ int
 cbc_init_ctx(cbc_ctx_t *cbc_ctx, char *param, size_t param_len,
     size_t block_size, void (*copy_block)(uint8_t *, uint64_t *))
 {
-	/*
-	 * Copy IV into context.
-	 *
-	 * If cm_param == NULL then the IV comes from the
-	 * cd_miscdata field in the crypto_data structure.
-	 */
-	if (param != NULL) {
-		ASSERT(param_len == block_size);
-		copy_block((uchar_t *)param, cbc_ctx->cbc_iv);
-	}
+	/* Copy IV into context. */
+	ASSERT3P(param, !=, NULL);
+	ASSERT3U(param_len, ==, block_size);
+
+	copy_block((uchar_t *)param, cbc_ctx->cbc_iv);
 
-	cbc_ctx->cbc_lastp = (uint8_t *)&cbc_ctx->cbc_iv[0];
-	cbc_ctx->cbc_flags |= CBC_MODE;
 	return (CRYPTO_SUCCESS);
 }
 
diff --git a/module/icp/core/kcf_prov_lib.c b/module/icp/core/kcf_prov_lib.c
index c65a9111a..505dbec31 100644
--- a/module/icp/core/kcf_prov_lib.c
+++ b/module/icp/core/kcf_prov_lib.c
@@ -114,33 +114,21 @@ crypto_put_output_data(uchar_t *buf, crypto_data_t *output, int len)
 
 int
 crypto_update_iov(void *ctx, crypto_data_t *input, crypto_data_t *output,
-    int (*cipher)(void *, caddr_t, size_t, crypto_data_t *),
-    void (*copy_block)(uint8_t *, uint64_t *))
+    int (*cipher)(void *, caddr_t, size_t, crypto_data_t *))
 {
-	common_ctx_t *common_ctx = ctx;
-	int rv;
-
 	ASSERT(input != output);
-	if (input->cd_miscdata != NULL) {
-		copy_block((uint8_t *)input->cd_miscdata,
-		    &common_ctx->cc_iv[0]);
-	}
 
 	if (input->cd_raw.iov_len < input->cd_length)
 		return (CRYPTO_ARGUMENTS_BAD);
 
-	rv = (cipher)(ctx, input->cd_raw.iov_base + input->cd_offset,
-	    input->cd_length, output);
-
-	return (rv);
+	return ((cipher)(ctx, input->cd_raw.iov_base + input->cd_offset,
+	    input->cd_length, output));
 }
 
 int
 crypto_update_uio(void *ctx, crypto_data_t *input, crypto_data_t *output,
-    int (*cipher)(void *, caddr_t, size_t, crypto_data_t *),
-    void (*copy_block)(uint8_t *, uint64_t *))
+    int (*cipher)(void *, caddr_t, size_t, crypto_data_t *))
 {
-	common_ctx_t *common_ctx = ctx;
 	zfs_uio_t *uiop = input->cd_uio;
 	off_t offset = input->cd_offset;
 	size_t length = input->cd_length;
@@ -148,10 +136,6 @@ crypto_update_uio(void *ctx, crypto_data_t *input, crypto_data_t *output,
 	size_t cur_len;
 
 	ASSERT(input != output);
-	if (input->cd_miscdata != NULL) {
-		copy_block((uint8_t *)input->cd_miscdata,
-		    &common_ctx->cc_iv[0]);
-	}
 
 	if (zfs_uio_segflg(input->cd_uio) != UIO_SYSSPACE) {
 		return (CRYPTO_ARGUMENTS_BAD);
diff --git a/module/icp/include/sys/crypto/impl.h b/module/icp/include/sys/crypto/impl.h
index da00c4001..03e7a6771 100644
--- a/module/icp/include/sys/crypto/impl.h
+++ b/module/icp/include/sys/crypto/impl.h
@@ -481,11 +481,9 @@ extern void kcf_free_provider_desc(kcf_provider_desc_t *);
 extern void undo_register_provider(kcf_provider_desc_t *, boolean_t);
 extern int crypto_put_output_data(uchar_t *, crypto_data_t *, int);
 extern int crypto_update_iov(void *, crypto_data_t *, crypto_data_t *,
-    int (*cipher)(void *, caddr_t, size_t, crypto_data_t *),
-    void (*copy_block)(uint8_t *, uint64_t *));
+    int (*cipher)(void *, caddr_t, size_t, crypto_data_t *));
 extern int crypto_update_uio(void *, crypto_data_t *, crypto_data_t *,
-    int (*cipher)(void *, caddr_t, size_t, crypto_data_t *),
-    void (*copy_block)(uint8_t *, uint64_t *));
+    int (*cipher)(void *, caddr_t, size_t, crypto_data_t *));
 
 /* Access to the provider's table */
 extern void kcf_prov_tab_destroy(void);
diff --git a/module/icp/io/aes.c b/module/icp/io/aes.c
index be3ced6d9..ad8a15a72 100644
--- a/module/icp/io/aes.c
+++ b/module/icp/io/aes.c
@@ -582,13 +582,11 @@ aes_encrypt_update(crypto_ctx_t *ctx, crypto_data_t *plaintext,
 	switch (plaintext->cd_format) {
 	case CRYPTO_DATA_RAW:
 		ret = crypto_update_iov(ctx->cc_provider_private,
-		    plaintext, ciphertext, aes_encrypt_contiguous_blocks,
-		    aes_copy_block64);
+		    plaintext, ciphertext, aes_encrypt_contiguous_blocks);
 		break;
 	case CRYPTO_DATA_UIO:
 		ret = crypto_update_uio(ctx->cc_provider_private,
-		    plaintext, ciphertext, aes_encrypt_contiguous_blocks,
-		    aes_copy_block64);
+		    plaintext, ciphertext, aes_encrypt_contiguous_blocks);
 		break;
 	default:
 		ret = CRYPTO_ARGUMENTS_BAD;
@@ -661,13 +659,11 @@ aes_decrypt_update(crypto_ctx_t *ctx, crypto_data_t *ciphertext,
 	switch (ciphertext->cd_format) {
 	case CRYPTO_DATA_RAW:
 		ret = crypto_update_iov(ctx->cc_provider_private,
-		    ciphertext, plaintext, aes_decrypt_contiguous_blocks,
-		    aes_copy_block64);
+		    ciphertext, plaintext, aes_decrypt_contiguous_blocks);
 		break;
 	case CRYPTO_DATA_UIO:
 		ret = crypto_update_uio(ctx->cc_provider_private,
-		    ciphertext, plaintext, aes_decrypt_contiguous_blocks,
-		    aes_copy_block64);
+		    ciphertext, plaintext, aes_decrypt_contiguous_blocks);
 		break;
 	default:
 		ret = CRYPTO_ARGUMENTS_BAD;
@@ -930,11 +926,11 @@ aes_encrypt_atomic(crypto_provider_handle_t provider,
 	switch (plaintext->cd_format) {
 	case CRYPTO_DATA_RAW:
 		ret = crypto_update_iov(&aes_ctx, plaintext, ciphertext,
-		    aes_encrypt_contiguous_blocks, aes_copy_block64);
+		    aes_encrypt_contiguous_blocks);
 		break;
 	case CRYPTO_DATA_UIO:
 		ret = crypto_update_uio(&aes_ctx, plaintext, ciphertext,
-		    aes_encrypt_contiguous_blocks, aes_copy_block64);
+		    aes_encrypt_contiguous_blocks);
 		break;
 	default:
 		ret = CRYPTO_ARGUMENTS_BAD;
@@ -1071,11 +1067,11 @@ aes_decrypt_atomic(crypto_provider_handle_t provider,
 	switch (ciphertext->cd_format) {
 	case CRYPTO_DATA_RAW:
 		ret = crypto_update_iov(&aes_ctx, ciphertext, plaintext,
-		    aes_decrypt_contiguous_blocks, aes_copy_block64);
+		    aes_decrypt_contiguous_blocks);
 		break;
 	case CRYPTO_DATA_UIO:
 		ret = crypto_update_uio(&aes_ctx, ciphertext, plaintext,
-		    aes_decrypt_contiguous_blocks, aes_copy_block64);
+		    aes_decrypt_contiguous_blocks);
 		break;
 	default:
 		ret = CRYPTO_ARGUMENTS_BAD;
diff --git a/module/os/linux/zfs/zio_crypt.c b/module/os/linux/zfs/zio_crypt.c
index 909246f20..31126a78b 100644
--- a/module/os/linux/zfs/zio_crypt.c
+++ b/module/os/linux/zfs/zio_crypt.c
@@ -438,13 +438,11 @@ zio_do_crypt_uio(boolean_t encrypt, uint64_t crypt, crypto_key_t *key,
 	plaindata.cd_format = CRYPTO_DATA_UIO;
 	plaindata.cd_offset = 0;
 	plaindata.cd_uio = puio;
-	plaindata.cd_miscdata = NULL;
 	plaindata.cd_length = plain_full_len;
 
 	cipherdata.cd_format = CRYPTO_DATA_UIO;
 	cipherdata.cd_offset = 0;
 	cipherdata.cd_uio = cuio;
-	cipherdata.cd_miscdata = NULL;
 	cipherdata.cd_length = datalen + maclen;
 
 	/* perform the actual encryption */