Add comments and copyright notices.

aes.asm

@@ -1,6 +1,33 @@
+* Copyright (c) 2017 Stephen Heumann
+*
+* Permission to use, copy, modify, and distribute this software for any
+* purpose with or without fee is hereby granted, provided that the above
+* copyright notice and this permission notice appear in all copies.
+*
+* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+
+* AES encryption and decryption functions for the 65816
+*
+* The general approach is largely based on the public domain
+* 'aestable.c' implementation by Karl Malbrain, available at:
+* https://code.google.com/archive/p/byte-oriented-aes/downloads
+* Portions are also based on the public domain 'rijndael-alg-fst.c'
+* reference implementation by Vincent Rijmen, Antoon Bosselaers,
+* and Paulo Barreto.
+
+
 	case	on
 	mcopy	aes.macros
 
+* Data tables used for AES encryption and decryption.
+* For best performance, these should be page-aligned.
 	align	256
 tables	privdata
 Sbox	anop		; forward s-box
@@ -181,6 +208,7 @@ Rcon	anop
 	dc h'ab 1b 40'
 	end
 
+* Direct page locations
 state1	gequ	0
 state2	gequ	16
 keysize	gequ	32
@@ -192,7 +220,11 @@ keysize_192 gequ 64
 keysize_256 gequ 128
 
 
-* Callable from C, with state structure pointer on stack.
+* AES key expansion functions
+* The appropriate one of these must be called before encrypting or decrypting.
+* The key should be in the first 16/24/32 bytes of rk before calling this.
+
+* Callable from C, with context structure pointer on stack.
 aes128_expandkey start
 	CFunction AES128_EXPANDKEY
 	end
@@ -205,7 +237,7 @@ aes256_expandkey start
 	CFunction AES256_EXPANDKEY
 	end
 
-* Call with DP = AES state structure (with key expanded),
+* Call with DP = AES context structure (with key present but not expanded),
 *           DB = bank containing AES tables.
 AES128_EXPANDKEY start
 	using	tables
@@ -281,13 +313,17 @@ done	rtl
 	end
 
 
-* Callable from C, with state structure pointer on stack.
+* AES encryption function
+* This performs AES-128, AES-192, or AES-256 encryption, depending on the key.
+* The unencrypted input and encrypted output are in state1.
+
+* Callable from C, with context structure pointer on stack.
 aes_encrypt start
 	CFunction AES_ENCRYPT
 	end
 
 
-* Call with DP = AES state structure (with key expanded),
+* Call with DP = AES context structure (with key expanded),
 *           DP = bank containing AES tables.
 AES_ENCRYPT start
 	using	tables
@@ -337,6 +373,10 @@ finish_aes128 anop
 	end
 
 
+* AES decryption functions
+* The encrypted input and unencrypted output are in state1.
+
+* Callable from C, with context structure pointer on stack.
 aes128_decrypt start
 	CFunction AES128_DECRYPT
 	end
@@ -349,6 +389,8 @@ aes256_decrypt start
 	CFunction AES256_DECRYPT
 	end
 
+* Call with DP = AES context structure (with key expanded),
+*           DP = bank containing AES tables.
 AES256_DECRYPT start
 	using	tables
 	ShortRegs

aes.h

@@ -1,3 +1,19 @@
+/*
+ * Copyright (c) 2017 Stephen Heumann
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
 struct aes_context {
 	unsigned char data[16];
 	unsigned char reserved1[17];
@@ -5,13 +21,28 @@ struct aes_context {
 	unsigned char reserved2[16*13];
 };
 
-/* context must be in bank 0, preferably page-aligned. */
+/* The context structure must be in bank 0, preferably page-aligned. */
-void aes128_expandkey(struct aes_context *);
-void aes128_expandkey(struct aes_context *);
-void aes128_expandkey(struct aes_context *);
 
-void aes_encrypt(struct aes_context *);
+/*
+ * AES key expansion functions
+ * The appropriate one of these must be called before encrypting or decrypting.
+ * The key must be in the first 16/24/32 bytes of context->key before the call.
+ */
+void aes128_expandkey(struct aes_context *context);
+void aes192_expandkey(struct aes_context *context);
+void aes256_expandkey(struct aes_context *context);
 
-void aes128_decrypt(struct aes_context *);
+/*
-void aes192_decrypt(struct aes_context *);
+ * AES encryption function
-void aes256_decrypt(struct aes_context *);
+ * This performs AES-128, AES-192, or AES-256 encryption, depending on the key.
+ * The unencrypted input and encrypted output are in context->data.
+ */
+void aes_encrypt(struct aes_context *context);
+
+/*
+ * AES decryption functions
+ * The encrypted input and unencrypted output are in context->data.
+ */
+void aes128_decrypt(struct aes_context *context);
+void aes192_decrypt(struct aes_context *context);
+void aes256_decrypt(struct aes_context *context);

aes.macros

@@ -1,3 +1,17 @@
+* Copyright (c) 2017 Stephen Heumann
+*
+* Permission to use, copy, modify, and distribute this software for any
+* purpose with or without fee is hereby granted, provided that the above
+* copyright notice and this permission notice appear in all copies.
+*
+* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
 * This makes a function wrapper that is callable from C,
 * taking a pointer to the state structure as its argument.
 	macro
@@ -18,7 +32,7 @@
 	rtl
 	mend
 
-
+*The 'core' function applied to some words when computing the AES key schedule
 	macro
 	ExpandKeyCore &xorback,&rconoffset
 
@@ -79,7 +93,7 @@
 
 	mend
 
-
+* Generate consecutive words of key schedule that don't use above functions
 	macro
 	ExpandKeyIter &xorback,&nwords
 	lcla	&i
@@ -99,7 +113,7 @@
 	aif	&i/4<&nwords,.loop2
 	mend
 
-
+* Do an initial AddRoundKey step on the starting state (for encryption)
 	macro
 	AddInitialRoundKey
 	lcla	&i
@@ -111,7 +125,7 @@
 	aif	&i<16,.top
 	mend
 
-
+* Do a full normal round, including (in effect) SubBytes through AddRoundKey
 	macro
 &lbl	NormalRound &round
 &lbl	anop
@@ -129,7 +143,7 @@
 .done
 	mend
 
-
+* Do the operations on one column for a normal round.
 	macro
 	MixColumn &i,&A,&B,&C,&D,&state,&out
 
@@ -183,7 +197,7 @@
 .skip2
 	mend
 
-
+* Do final round, including (in effect) SubBytes, ShiftRows, and AddRoundKey.
 	macro
 	FinalRound &round
 
@@ -209,7 +223,7 @@
 	
 	mend
 
-
+* Do the final round operations for one byte.
 	macro
 	FinalRoundStep &to,&from,&skipldy
 
@@ -228,7 +242,7 @@
 
 	mend
 
-
+* Perform an inverse normal round (for decryption)
 	macro
 	InvNormalRound &round,&state
 	lcla	&i
@@ -250,7 +264,7 @@
 	InvMixColumn 4,9,14,3,4,dotax=1
 	mend
 
-
+* Perform the operations for one column in an inverse normal round
 	macro
 	InvMixColumn &A,&B,&C,&D,&i,&skipldx,&dotax
 
@@ -311,7 +325,7 @@
 .done
 	mend
 
-
+* Do the inverse final round steps for one byte.
 	macro
 	InvFinalRoundStep &to,&from,&dotax
 	
@@ -341,7 +355,7 @@
 .done
 	mend
 
-
+* Do the inverse of the final round (which comes first for decryption).
 	macro
 	InvFinalRound &round
 	
@@ -367,7 +381,7 @@
 	
 	mend
 	
-
+* Set registers to 8 bits
 	macro
 	ShortRegs
 	sep	#$30
@@ -375,11 +389,10 @@
 	longi	off
 	mend
 
-
+* Set registers to 16 bits
 	macro
 	LongRegs
 	rep	#$30
 	longa	on
 	longi	on
 	mend
-

aestest.c

@@ -1,3 +1,19 @@
+/*
+ * Copyright (c) 2017 Stephen Heumann
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
 #include <stdio.h>
 #include <MiscTool.h>
 #include <Memory.h>