1 files changed, 137 insertions, 0 deletions
diff --git a/xmss_hash.c b/xmss_hash.c
new file mode 100644
index 0000000..db0e5fa
--- /dev/null
+++ b/xmss_hash.c
@@ -0,0 +1,137 @@
+/* $OpenBSD: xmss_hash.c,v 1.3 2022/04/20 16:00:25 millert Exp $ */
+/*
+hash.c version 20160722
+Andreas Hülsing
+Joost Rijneveld
+Public domain.
+*/
+
+#include "includes.h"
+#ifdef WITH_XMSS
+
+#include "xmss_hash_address.h"
+#include "xmss_commons.h"
+#include "xmss_hash.h"
+
+#include <stddef.h>
+#ifdef HAVE_STDINT_H
+# include <stdint.h>
+#endif
+#include <stdio.h>
+#include <string.h>
+
+int core_hash_SHA2(unsigned char *, const unsigned int, const unsigned char *,
+    unsigned int, const unsigned char *, unsigned long long, unsigned int);
+
+unsigned char* addr_to_byte(unsigned char *bytes, const uint32_t addr[8]){
+#if IS_LITTLE_ENDIAN==1 
+  int i = 0;
+  for(i=0;i<8;i++)
+    to_byte(bytes+i*4, addr[i],4);
+  return bytes;  
+#else
+  memcpy(bytes, addr, 32);
+  return bytes; 
+#endif   
+}
+
+int core_hash_SHA2(unsigned char *out, const unsigned int type, const unsigned char *key, unsigned int keylen, const unsigned char *in, unsigned long long inlen, unsigned int n){  
+  unsigned long long i = 0;
+  unsigned char buf[inlen + n + keylen];
+  
+  // Input is (toByte(X, 32) || KEY || M) 
+  
+  // set toByte
+  to_byte(buf, type, n);
+  
+  for (i=0; i < keylen; i++) {
+    buf[i+n] = key[i];
+  }
+  
+  for (i=0; i < inlen; i++) {
+    buf[keylen + n + i] = in[i];
+  }
+
+  if (n == 32) {
+    SHA256(buf, inlen + keylen + n, out);
+    return 0;
+  }
+  else {
+    if (n == 64) {
+      SHA512(buf, inlen + keylen + n, out);
+      return 0;
+    }
+  }
+  return 1;
+}
+
+/**
+ * Implements PRF
+ */
+int prf(unsigned char *out, const unsigned char *in, const unsigned char *key, unsigned int keylen)
+{ 
+  return core_hash_SHA2(out, 3, key, keylen, in, 32, keylen);
+}
+
+/*
+ * Implemts H_msg
+ */
+int h_msg(unsigned char *out, const unsigned char *in, unsigned long long inlen, const unsigned char *key, const unsigned int keylen, const unsigned int n)
+{
+  if (keylen != 3*n){
+    // H_msg takes 3n-bit keys, but n does not match the keylength of keylen
+    return -1;
+  }  
+  return core_hash_SHA2(out, 2, key, keylen, in, inlen, n);
+}
+
+/**
+ * We assume the left half is in in[0]...in[n-1]
+ */
+int hash_h(unsigned char *out, const unsigned char *in, const unsigned char *pub_seed, uint32_t addr[8], const unsigned int n)
+{
+
+  unsigned char buf[2*n];
+  unsigned char key[n];
+  unsigned char bitmask[2*n];
+  unsigned char byte_addr[32];
+  unsigned int i;
+
+  setKeyAndMask(addr, 0);
+  addr_to_byte(byte_addr, addr);
+  prf(key, byte_addr, pub_seed, n);
+  // Use MSB order
+  setKeyAndMask(addr, 1);
+  addr_to_byte(byte_addr, addr);
+  prf(bitmask, byte_addr, pub_seed, n);
+  setKeyAndMask(addr, 2);
+  addr_to_byte(byte_addr, addr);
+  prf(bitmask+n, byte_addr, pub_seed, n);
+  for (i = 0; i < 2*n; i++) {
+    buf[i] = in[i] ^ bitmask[i];
+  }
+  return core_hash_SHA2(out, 1, key, n, buf, 2*n, n);
+}
+
+int hash_f(unsigned char *out, const unsigned char *in, const unsigned char *pub_seed, uint32_t addr[8], const unsigned int n)
+{
+  unsigned char buf[n];
+  unsigned char key[n];
+  unsigned char bitmask[n];
+  unsigned char byte_addr[32];
+  unsigned int i;
+
+  setKeyAndMask(addr, 0);  
+  addr_to_byte(byte_addr, addr);  
+  prf(key, byte_addr, pub_seed, n);
+  
+  setKeyAndMask(addr, 1);
+  addr_to_byte(byte_addr, addr);
+  prf(bitmask, byte_addr, pub_seed, n);
+  
+  for (i = 0; i < n; i++) {
+    buf[i] = in[i] ^ bitmask[i];
+  }
+  return core_hash_SHA2(out, 0, key, n, buf, n, n);
+}
+#endif /* WITH_XMSS */