diff options
| author | Matthias Andreas Benkard <code@mail.matthias.benkard.de> | 2011-08-16 15:48:06 +0200 |
|---|---|---|
| committer | Matthias Andreas Benkard <code@mail.matthias.benkard.de> | 2011-08-16 15:48:06 +0200 |
| commit | 8a5aa2f4b6b3f26daa886faceae6fe6547ab2187 (patch) | |
| tree | 45ff4f3dca5240807e515537b9e4f5eabf85af6e | |
| parent | 93515cf43ce16974c7bef1d1d8332e3c8cfe6fac (diff) | |
Salsa20: Use a producer function for generating the output sequence.
| -rw-r--r-- | salsa-chacha.rkt | 52 |
1 files changed, 30 insertions, 22 deletions
diff --git a/salsa-chacha.rkt b/salsa-chacha.rkt index 17af9c8..e5a087d 100644 --- a/salsa-chacha.rkt +++ b/salsa-chacha.rkt @@ -21,15 +21,18 @@ (provide salsa20) -(require/typed racket/stream - [empty-stream #;(All (a) (Sequenceof a)) - (Sequenceof Byte)]) - (require/typed racket [sequence-generate (All (a) (Sequenceof a) -> (values (-> Boolean) - (-> a)))]) + (-> a)))] + #;[in-producer (All (a) + ((-> Any) + Any + -> (Sequenceof a)))] + [in-producer ((-> (U Byte Symbol)) + Symbol + -> (Sequenceof Byte))]) (require/typed "typed-stream.rkt" [lazy-functional-stream-append (All (a) @@ -167,20 +170,25 @@ (: salsa20 (Bytes Bytes (Sequenceof Byte) -> (Sequenceof Byte))) (define (salsa20 k v m) (let-values ([(next? next) (sequence-generate m)]) - (let: loop : (Sequenceof Byte) - ([i : Word 0]) - (if (next?) - (let ([64bytes - (let: inner-loop : Bytes - ([k : Integer 0] - [bytes : (Listof Byte) (list)]) - (if (and (next?) (< k 64)) - (inner-loop (add1 k) (cons (next) bytes)) - (list->bytes bytes)))] - [i-code - (integer->bytes/size i 'little-endian 8)]) - (lazy-functional-stream-append (ann (bytes-xor 64bytes - (salsa20k k (bytes-append v i-code))) - (Sequenceof Byte)) - (λ () (loop (add1 i))))) - empty-stream)))) + (let: ([i : Word 0] + [buffer : (Listof Byte) (list)]) + (in-producer + (λ () + (when (null? buffer) + (let ([64bytes + (let: inner-loop : Bytes + ([k : Integer 0] + [bytes : (Listof Byte) (list)]) + (if (and (next?) (< k 64)) + (inner-loop (add1 k) (cons (next) bytes)) + (list->bytes bytes)))] + [i-code + (integer->bytes/size i 'little-endian 8)]) + (set! buffer (bytes->list (bytes-xor 64bytes + (salsa20k k (bytes-append v i-code))))))) + (if (null? buffer) + 'end-of-sequence + (let ([byte (first buffer)]) + (set! buffer (rest buffer)) + byte))) + 'end-of-sequence)))) |