1	# bend-osdev-crypto: one set of typed interfaces for the cryptographic
2	# algorithms of bend-osdev, the Bend counterpart of Linux's crypto API.
3	#
4	# An interface is a signature of template arguments: an algorithm satisfies it
5	# by supplying a def of each type, and a generic algorithm (HMAC over a hash,
6	# a mode over a block cipher) takes the signature as its own template
7	# arguments, so it is specialised at compile time for each algorithm it runs
8	# over. The interfaces, one file each:
9	#
10	#   block.bend    block cipher: key schedule, encrypt and decrypt a block
11	#   stream.bend   stream cipher: a state that encrypts the next piece of data
12	#   hash.bend     hash: streaming init / update / final, and one-shot
13	#   mac.bend      message authentication code: compute and verify
14	#   aead.bend     authenticated encryption with associated data: seal, open
15	#   kdf.bend      key derivation
16	#   sign.bend     signature: sign and verify
17	#   kex.bend      key agreement
18	#
19	# Each interface has laws that every instance must satisfy; README.md states
20	# them and gen/instances.py writes one law per instance into LAWS.bend. This
21	# file holds what every interface shares: the error type.
22	import Base
23	import bend-osdev-bytes@0.1.0.0/bytes.bend as B
24	
25	# Every failure an interface reports. An instance whose algorithm has its own
26	# error type maps it onto these (inst_lc.bend, inst_cm.bend).
27	type CrError is Data:
28	  CrBadKeyLength{got: Nat}
29	  CrBadIvLength{got: Nat}
30	  CrBadNonceLength{got: Nat}
31	  CrBadTagLength{got: Nat}
32	  CrBadBlockSize{got: Nat}
33	  CrNotBlockMultiple{len: Nat}
34	  CrTooShort{len: Nat}
35	  CrTooLong{len: Nat}
36	  CrBadPadding{}
37	  CrTagMismatch{}
38	  CrBadOutputLength{got: Nat}
39	  CrBadKey{}
40	  CrBadPublicKey{}
41	
42	# A check, as a step of a Result block
43	def CrError.check(ok: Bool, e: CrError) -> Result<&2, &2, CrError, Unit>:
44	  match ok:
45	    case True{}:
46	      Done{Unit{}}
47	    case False{}:
48	      Fail{e}
49	
50	# A result with an algorithm's own error type, its error mapped onto CrError
51	def CrError.lift(~E: Data, ~A: Data, ~f: E -> CrError, r: Result<&2, &2, E, A>) -> Result<&2, &2, CrError, A>:
52	  match r:
53	    case Fail{e}:
54	      Fail{f(e)}
55	    case Done{x}:
56	      Done{x}