From e6720ad3df308f04bc0a151f64a370b7a804f13a Mon Sep 17 00:00:00 2001
From: Valentin Gehrke <madmaurice@zom.bi>
Date: Fri, 14 Jul 2017 16:30:17 +0200
Subject: [PATCH] SHA1 Implementierung

---
 sha1.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100644 sha1.c

diff --git a/sha1.c b/sha1.c
new file mode 100644
index 0000000..1200def
--- /dev/null
+++ b/sha1.c
@@ -0,0 +1,117 @@
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+typedef struct {
+  uint32_t h0;
+  uint32_t h1;
+  uint32_t h2;
+  uint32_t h3;
+  uint32_t h4;
+} hash_t;
+
+hash_t* sha1(const char* s, hash_t* h);
+void printhash(hash_t* h);
+
+void main(int argc, char** argv) {
+  hash_t h;
+  const char* str;
+  if(argc > 1) {
+	str = argv[1];
+  } else {
+	str = "test";
+  }
+  sha1(str,&h);
+  printhash(&h);
+}
+
+void printhash(hash_t* h) {
+  printf("%08X%08X%08X%08X%08X\n",
+		 h->h0,
+		 h->h1,
+		 h->h2,
+		 h->h3,
+		 h->h4);
+}
+
+#define left_shift(n,X) (((X) << (n)) | ((X) >> (32-(n))))
+
+void apply_round(const char* block, hash_t* state) {
+  uint32_t A,B,C,D,E;
+  uint32_t W[80];
+  uint32_t temp, K, f;
+
+  for(int i = 0; i < 16; i++) {
+	W[i] = (unsigned char)block[i*4] << 24;
+	W[i] |= (unsigned char)block[i*4+1] << 16;
+	W[i] |= (unsigned char)block[i*4+2] << 8;
+	W[i] |= (unsigned char)block[i*4+3];
+  }
+
+  for(int i = 16; i < 80; i++) {
+	W[i] = left_shift(1, W[i-3] ^ W[i-8] ^ W[i-14] ^ W[i-16]);
+  }
+
+  A = state->h0;
+  B = state->h1;
+  C = state->h2;
+  D = state->h3;
+  E = state->h4;
+
+  for(int i = 0; i < 80; i++) {
+	if(0 <= i && i <= 19) {
+	  f = (B & C) | ( (~B) & D );
+	  K = 0x5A827999;
+	} else if(20 <= i && i <= 39) {
+	  f = B ^ C ^ D;
+	  K = 0x6ED9EBA1;
+	} else if(40 <= i && i <= 59) {
+	  f = (B & C) | (B & D) | (C & D);
+	  K = 0x8F1BBCDC;
+	} else if(60 <= i && i <= 79) {
+	  f = B ^ C ^ D;
+	  K = 0xCA62C1D6;
+	}
+
+	temp = left_shift(5,A) + f + E + W[i] + K;
+	E = D; D = C; C = left_shift(30,B); B = A; A = temp;
+  }
+  
+  state->h0 += A;
+  state->h1 += B;
+  state->h2 += C;
+  state->h3 += D;
+  state->h4 += E;
+}
+
+hash_t* sha1(const char* s, hash_t* H) {
+  H->h0 = 0x67452301;
+  H->h1 = 0xEFCDAB89;
+  H->h2 = 0x98BADCFE;
+  H->h3 = 0x10325476;
+  H->h4 = 0xC3D2E1F0;
+
+  size_t slen = strlen(s);
+  size_t bitlen = slen*8;
+  unsigned long long padlen = (slen + 64 - (slen%512));
+  if(padlen - slen < 8) padlen += 64;
+  
+  char buf[padlen];
+
+  memset(buf, 0, sizeof(char) * padlen);
+  memcpy(buf, s, sizeof(char) * slen);
+
+  buf[slen] = 0x80;
+  for(int i = 0; i < 8; i++) {
+	buf[padlen-i-1] = (bitlen >> (8*i)) & 0xFF;
+  }
+
+  size_t numblocks = padlen / 64;
+
+  for(int i = 0; i < numblocks; i++) {
+	apply_round(&(buf[i*64]),H);
+  }
+
+  return H;
+}