Index: sys/opencrypto/cryptosoft.c
===================================================================
--- sys/opencrypto/cryptosoft.c
+++ sys/opencrypto/cryptosoft.c
@@ -105,7 +105,7 @@
 	const struct enc_xform *exf;
 	const struct swcr_encdec *sw;
 	void *ctx;
-	size_t inlen, outlen;
+	size_t inlen, outlen, todo;
 	int blks, resid;
 	struct crypto_buffer_cursor cc_in, cc_out;
 	const unsigned char *inblk;
@@ -172,33 +172,38 @@
 		if (inlen < blks) {
 			crypto_cursor_copydata(&cc_in, blks, blk);
 			inblk = blk;
+			inlen = blks;
 		}
-		if (outlen < blks)
-			outblk = blk;
-
-		if (encrypting)
-			exf->encrypt(ctx, inblk, outblk);
-		else
-			exf->decrypt(ctx, inblk, outblk);
-
-		if (inlen < blks) {
-			inblk = crypto_cursor_segment(&cc_in, &inlen);
-		} else {
-			crypto_cursor_advance(&cc_in, blks);
-			inlen -= blks;
-			inblk += blks;
-		}
-
 		if (outlen < blks) {
+			outblk = blk;
+			outlen = blks;
+		}
+
+		todo = rounddown2(MIN(resid, MIN(inlen, outlen)), blks);
+
+		if (encrypting)
+			exf->encrypt_multi(ctx, inblk, outblk, todo);
+		else
+			exf->decrypt_multi(ctx, inblk, outblk, todo);
+
+		if (inblk == blk) {
+			inblk = crypto_cursor_segment(&cc_in, &inlen);
+		} else {
+			crypto_cursor_advance(&cc_in, todo);
+			inlen -= todo;
+			inblk += todo;
+		}
+
+		if (outblk == blk) {
 			crypto_cursor_copyback(&cc_out, blks, blk);
 			outblk = crypto_cursor_segment(&cc_out, &outlen);
 		} else {
-			crypto_cursor_advance(&cc_out, blks);
-			outlen -= blks;
-			outblk += blks;
+			crypto_cursor_advance(&cc_out, todo);
+			outlen -= todo;
+			outblk += todo;
 		}
 
-		resid -= blks;
+		resid -= todo;
 	}
 
 	/* Handle trailing partial block for stream ciphers. */