diff --git a/sys/dev/safexcel/safexcel.c b/sys/dev/safexcel/safexcel.c
--- a/sys/dev/safexcel/safexcel.c
+++ b/sys/dev/safexcel/safexcel.c
@@ -2,6 +2,10 @@
  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
  *
  * Copyright (c) 2020, 2021 Rubicon Communications, LLC (Netgate)
+ * Copyright (c) 2021 The FreeBSD Foundation
+ *
+ * Portions of this software were developed by Ararat River
+ * Consulting, LLC under sponsorship of the FreeBSD Foundation.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -1689,12 +1693,14 @@
 safexcel_instr_ccm(struct safexcel_request *req, struct safexcel_instr *instr,
     struct safexcel_cmd_descr *cdesc)
 {
+	const struct crypto_session_params *csp;
 	struct cryptop *crp;
 	struct safexcel_instr *start;
 	uint8_t *a0, *b0, *alenp, L;
 	int aalign, blen;
 
 	crp = req->crp;
+	csp = crypto_get_params(crp->crp_session);
 	start = instr;
 
 	/*
@@ -1703,17 +1709,17 @@
 	 * descriptor, and B0 is inserted directly into the data stream using
 	 * instructions below.
 	 *
-	 * OCF seems to assume a 12-byte IV, fixing L (the payload length size)
-	 * at 3 bytes due to the layout of B0.  This is fine since the driver
-	 * has a maximum of 65535 bytes anyway.
+	 * An explicit check for overflow of the length field is not
+	 * needed since the maximum driver size of 65535 bytes fits in
+	 * the smallest length field used for a 13-byte nonce.
 	 */
 	blen = AES_BLOCK_LEN;
-	L = 3;
+	L = 15 - csp->csp_ivlen;
 
 	a0 = (uint8_t *)&cdesc->control_data.token[0];
 	memset(a0, 0, blen);
 	a0[0] = L - 1;
-	memcpy(&a0[1], req->iv, AES_CCM_IV_LEN);
+	memcpy(&a0[1], req->iv, csp->csp_ivlen);
 
 	/*
 	 * Insert B0 and the AAD length into the input stream.
@@ -1731,7 +1737,7 @@
 	    (L - 1) | /* payload length size */
 	    ((CCM_CBC_MAX_DIGEST_LEN - 2) / 2) << 3 /* digest length */ |
 	    (crp->crp_aad_length > 0 ? 1 : 0) << 6 /* AAD present bit */;
-	memcpy(&b0[1], req->iv, AES_CCM_IV_LEN);
+	memcpy(&b0[1], req->iv, csp->csp_ivlen);
 	b0[14] = crp->crp_payload_length >> 8;
 	b0[15] = crp->crp_payload_length & 0xff;
 	instr += blen / sizeof(*instr);
@@ -2308,7 +2314,8 @@
 				return (EINVAL);
 			break;
 		case CRYPTO_AES_CCM_16:
-			if (csp->csp_ivlen != AES_CCM_IV_LEN)
+			if (csp->csp_auth_mlen != 0 &&
+			    csp->csp_auth_mlen != AES_CBC_MAC_HASH_LEN)
 				return (EINVAL);
 			break;
 		default: