rust/src/lib/SHA1.rs

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/*
* A SHA-1 implementation derived from Paul E. Jones's reference
* implementation, which is written for clarity, not speed. At some
* point this will want to be rewritten.
*/
export sha1;
export mk_sha1;
state type sha1 = state obj {
// Provide message input as bytes
fn input(&vec[u8]);
// Provide message input as string
fn input_str(&str);
// Read the digest as a vector of 20 bytes. After
// calling this no further input may provided
// until reset is called
fn result() -> vec[u8];
// Same as above, just a hex-string version.
fn result_str() -> str;
// Reset the sha1 state for reuse. This is called
// automatically during construction
fn reset();
};
// Some unexported constants
const uint digest_buf_len = 5;
const uint msg_block_len = 64;
// Builds a sha1 object
fn mk_sha1() -> sha1 {
state type sha1state = rec(vec[mutable u32] h,
mutable u32 len_low,
mutable u32 len_high,
vec[mutable u8] msg_block,
mutable uint msg_block_idx,
mutable bool computed);
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fn add_input(&sha1state st, &vec[u8] msg) {
// FIXME: Should be typestate precondition
assert (!st.computed);
for (u8 element in msg) {
st.msg_block.(st.msg_block_idx) = element;
st.msg_block_idx += 1u;
st.len_low += 8u32;
if (st.len_low == 0u32) {
st.len_high += 1u32;
if (st.len_high == 0u32) {
// FIXME: Need better failure mode
fail;
}
}
if (st.msg_block_idx == msg_block_len) {
process_msg_block(st);
}
}
}
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fn process_msg_block(&sha1state st) {
// FIXME: Make precondition
assert (Vec.len(st.h) == digest_buf_len);
// Constants
auto k = vec(0x5A827999u32,
0x6ED9EBA1u32,
0x8F1BBCDCu32,
0xCA62C1D6u32);
let int t; // Loop counter
let vec[mutable u32] w = Vec.init_elt_mut[u32](0u32, 80u);
// Initialize the first 16 words of the vector w
t = 0;
while (t < 16) {
w.(t) = (st.msg_block.(t * 4) as u32) << 24u32;
w.(t) = w.(t) | ((st.msg_block.(t * 4 + 1) as u32) << 16u32);
w.(t) = w.(t) | ((st.msg_block.(t * 4 + 2) as u32) << 8u32);
w.(t) = w.(t) | (st.msg_block.(t * 4 + 3) as u32);
t += 1;
}
// Initialize the rest of vector w
while (t < 80) {
auto val = w.(t-3) ^ w.(t-8) ^ w.(t-14) ^ w.(t-16);
w.(t) = circular_shift(1u32, val);
t += 1;
}
auto a = st.h.(0);
auto b = st.h.(1);
auto c = st.h.(2);
auto d = st.h.(3);
auto e = st.h.(4);
let u32 temp;
t = 0;
while (t < 20) {
temp = circular_shift(5u32, a)
+ ((b & c) | ((~b) & d)) + e + w.(t) + k.(0);
e = d;
d = c;
c = circular_shift(30u32, b);
b = a;
a = temp;
t += 1;
}
while (t < 40) {
temp = circular_shift(5u32, a)
+ (b ^ c ^ d) + e + w.(t) + k.(1);
e = d;
d = c;
c = circular_shift(30u32, b);
b = a;
a = temp;
t += 1;
}
while (t < 60) {
temp = circular_shift(5u32, a)
+ ((b & c) | (b & d) | (c & d)) + e + w.(t) + k.(2);
e = d;
d = c;
c = circular_shift(30u32, b);
b = a;
a = temp;
t += 1;
}
while (t < 80) {
temp = circular_shift(5u32, a)
+ (b ^ c ^ d) + e + w.(t) + k.(3);
e = d;
d = c;
c = circular_shift(30u32, b);
b = a;
a = temp;
t += 1;
}
st.h.(0) = st.h.(0) + a;
st.h.(1) = st.h.(1) + b;
st.h.(2) = st.h.(2) + c;
st.h.(3) = st.h.(3) + d;
st.h.(4) = st.h.(4) + e;
st.msg_block_idx = 0u;
}
fn circular_shift(u32 bits, u32 word) -> u32 {
// FIXME: This is a workaround for a rustboot
// "unrecognized quads" codegen bug
auto bits_hack = bits;
ret (word << bits_hack) | (word >> (32u32 - bits));
}
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fn mk_result(&sha1state st) -> vec[u8] {
if (!st.computed) {
pad_msg(st);
st.computed = true;
}
let vec[u8] res = vec();
for (u32 hpart in st.h) {
auto a = (hpart >> 24u32) & 0xFFu32 as u8;
auto b = (hpart >> 16u32) & 0xFFu32 as u8;
auto c = (hpart >> 8u32) & 0xFFu32 as u8;
auto d = (hpart & 0xFFu32 as u8);
res += vec(a,b,c,d);
}
ret res;
}
/*
* According to the standard, the message must be padded to an even
* 512 bits. The first padding bit must be a '1'. The last 64 bits
* represent the length of the original message. All bits in between
* should be 0. This function will pad the message according to those
* rules by filling the msg_block vector accordingly. It will also
* call process_msg_block() appropriately. When it returns, it
* can be assumed that the message digest has been computed.
*/
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fn pad_msg(&sha1state st) {
// FIXME: Should be a precondition
assert (Vec.len(st.msg_block) == msg_block_len);
/*
* Check to see if the current message block is too small to hold
* the initial padding bits and length. If so, we will pad the
* block, process it, and then continue padding into a second block.
*/
if (st.msg_block_idx > 55u) {
st.msg_block.(st.msg_block_idx) = 0x80u8;
st.msg_block_idx += 1u;
while (st.msg_block_idx < msg_block_len) {
st.msg_block.(st.msg_block_idx) = 0u8;
st.msg_block_idx += 1u;
}
process_msg_block(st);
} else {
st.msg_block.(st.msg_block_idx) = 0x80u8;
st.msg_block_idx += 1u;
}
while (st.msg_block_idx < 56u) {
st.msg_block.(st.msg_block_idx) = 0u8;
st.msg_block_idx += 1u;
}
// Store the message length as the last 8 octets
st.msg_block.(56) = (st.len_high >> 24u32) & 0xFFu32 as u8;
st.msg_block.(57) = (st.len_high >> 16u32) & 0xFFu32 as u8;
st.msg_block.(58) = (st.len_high >> 8u32) & 0xFFu32 as u8;
st.msg_block.(59) = st.len_high & 0xFFu32 as u8;
st.msg_block.(60) = (st.len_low >> 24u32) & 0xFFu32 as u8;
st.msg_block.(61) = (st.len_low >> 16u32) & 0xFFu32 as u8;
st.msg_block.(62) = (st.len_low >> 8u32) & 0xFFu32 as u8;
st.msg_block.(63) = st.len_low & 0xFFu32 as u8;
process_msg_block(st);
}
state obj sha1(sha1state st) {
fn reset() {
// FIXME: Should be typestate precondition
assert (Vec.len(st.h) == digest_buf_len);
st.len_low = 0u32;
st.len_high = 0u32;
st.msg_block_idx = 0u;
st.h.(0) = 0x67452301u32;
st.h.(1) = 0xEFCDAB89u32;
st.h.(2) = 0x98BADCFEu32;
st.h.(3) = 0x10325476u32;
st.h.(4) = 0xC3D2E1F0u32;
st.computed = false;
}
fn input(&vec[u8] msg) {
add_input(st, msg);
}
fn input_str(&str msg) {
add_input(st, Str.bytes(msg));
}
fn result() -> vec[u8] {
ret mk_result(st);
}
fn result_str() -> str {
auto r = mk_result(st);
auto s = "";
for (u8 b in r) {
s += UInt.to_str(b as uint, 16u);
}
ret s;
}
}
auto st = rec(h = Vec.init_elt_mut[u32](0u32, digest_buf_len),
mutable len_low = 0u32,
mutable len_high = 0u32,
msg_block = Vec.init_elt_mut[u8](0u8, msg_block_len),
mutable msg_block_idx = 0u,
mutable computed = false);
auto sh = sha1(st);
sh.reset();
ret sh;
}
// Local Variables:
// mode: rust;
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C .. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End: