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diff --git a/sha1.c b/sha1.c
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+/*********************************************************************
+* Filename:   sha1.c
+* Author:     Brad Conte (brad AT bradconte.com)
+* Copyright:
+* Disclaimer: This code is presented "as is" without any guarantees.
+* Details:    Implementation of the SHA1 hashing algorithm.
+              Algorithm specification can be found here:
+               * http://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf
+              This implementation uses little endian byte order.
+*********************************************************************/
+
+/*************************** HEADER FILES ***************************/
+#include <stdlib.h>
+#include <memory.h>
+#include "sha1.h"
+
+/****************************** MACROS ******************************/
+#define ROTLEFT(a, b) ((a << b) | (a >> (32 - b)))
+
+/*********************** FUNCTION DEFINITIONS ***********************/
+void sha1_transform(SHA1_CTX *ctx, const BYTE data[])
+{
+	WORD a, b, c, d, e, i, j, t, m[80];
+
+	for (i = 0, j = 0; i < 16; ++i, j += 4)
+		m[i] = (data[j] << 24) + (data[j + 1] << 16) + (data[j + 2] << 8) + (data[j + 3]);
+	for ( ; i < 80; ++i) {
+		m[i] = (m[i - 3] ^ m[i - 8] ^ m[i - 14] ^ m[i - 16]);
+		m[i] = (m[i] << 1) | (m[i] >> 31);
+	}
+
+	a = ctx->state[0];
+	b = ctx->state[1];
+	c = ctx->state[2];
+	d = ctx->state[3];
+	e = ctx->state[4];
+
+	for (i = 0; i < 20; ++i) {
+		t = ROTLEFT(a, 5) + ((b & c) ^ (~b & d)) + e + ctx->k[0] + m[i];
+		e = d;
+		d = c;
+		c = ROTLEFT(b, 30);
+		b = a;
+		a = t;
+	}
+	for ( ; i < 40; ++i) {
+		t = ROTLEFT(a, 5) + (b ^ c ^ d) + e + ctx->k[1] + m[i];
+		e = d;
+		d = c;
+		c = ROTLEFT(b, 30);
+		b = a;
+		a = t;
+	}
+	for ( ; i < 60; ++i) {
+		t = ROTLEFT(a, 5) + ((b & c) ^ (b & d) ^ (c & d))  + e + ctx->k[2] + m[i];
+		e = d;
+		d = c;
+		c = ROTLEFT(b, 30);
+		b = a;
+		a = t;
+	}
+	for ( ; i < 80; ++i) {
+		t = ROTLEFT(a, 5) + (b ^ c ^ d) + e + ctx->k[3] + m[i];
+		e = d;
+		d = c;
+		c = ROTLEFT(b, 30);
+		b = a;
+		a = t;
+	}
+
+	ctx->state[0] += a;
+	ctx->state[1] += b;
+	ctx->state[2] += c;
+	ctx->state[3] += d;
+	ctx->state[4] += e;
+}
+
+void sha1_init(SHA1_CTX *ctx)
+{
+	ctx->datalen = 0;
+	ctx->bitlen = 0;
+	ctx->state[0] = 0x67452301;
+	ctx->state[1] = 0xEFCDAB89;
+	ctx->state[2] = 0x98BADCFE;
+	ctx->state[3] = 0x10325476;
+	ctx->state[4] = 0xc3d2e1f0;
+	ctx->k[0] = 0x5a827999;
+	ctx->k[1] = 0x6ed9eba1;
+	ctx->k[2] = 0x8f1bbcdc;
+	ctx->k[3] = 0xca62c1d6;
+}
+
+void sha1_update(SHA1_CTX *ctx, const BYTE data[], size_t len)
+{
+	size_t i;
+
+	for (i = 0; i < len; ++i) {
+		ctx->data[ctx->datalen] = data[i];
+		ctx->datalen++;
+		if (ctx->datalen == 64) {
+			sha1_transform(ctx, ctx->data);
+			ctx->bitlen += 512;
+			ctx->datalen = 0;
+		}
+	}
+}
+
+void sha1_final(SHA1_CTX *ctx, BYTE hash[])
+{
+	WORD i;
+
+	i = ctx->datalen;
+
+	// Pad whatever data is left in the buffer.
+	if (ctx->datalen < 56) {
+		ctx->data[i++] = 0x80;
+		while (i < 56)
+			ctx->data[i++] = 0x00;
+	}
+	else {
+		ctx->data[i++] = 0x80;
+		while (i < 64)
+			ctx->data[i++] = 0x00;
+		sha1_transform(ctx, ctx->data);
+		memset(ctx->data, 0, 56);
+	}
+
+	// Append to the padding the total message's length in bits and transform.
+	ctx->bitlen += ctx->datalen * 8;
+	ctx->data[63] = ctx->bitlen;
+	ctx->data[62] = ctx->bitlen >> 8;
+	ctx->data[61] = ctx->bitlen >> 16;
+	ctx->data[60] = ctx->bitlen >> 24;
+	ctx->data[59] = ctx->bitlen >> 32;
+	ctx->data[58] = ctx->bitlen >> 40;
+	ctx->data[57] = ctx->bitlen >> 48;
+	ctx->data[56] = ctx->bitlen >> 56;
+	sha1_transform(ctx, ctx->data);
+
+	// Since this implementation uses little endian byte ordering and MD uses big endian,
+	// reverse all the bytes when copying the final state to the output hash.
+	for (i = 0; i < 4; ++i) {
+		hash[i]      = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff;
+		hash[i + 4]  = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff;
+		hash[i + 8]  = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff;
+		hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff;
+		hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff;
+	}
+}