added pcp_ed_verify_buffered() [doesnt work yet, needs debugging]

include/pcp/defines.h

@@ -40,9 +40,10 @@ typedef unsigned int    qbyte;          //  Quad byte = 32 bits
 #define PCP_ZFILE_HEADER "----- BEGIN Z85 ENCODED FILE -----"
 #define PCP_ZFILE_FOOTER "------ END Z85 ENCODED FILE ------"
 
-#define PCP_SIG_HEADER "----- BEGIN PCP SIGNED MESSAGE -----"
-#define PCP_SIG_START  "----- BEGIN PCP SIGNATURE -----"
-#define PCP_SIG_END    "------ END PCP SIGNATURE ------"
+#define PCP_SIG_HEADER "----- BEGIN ED25519 SIGNED MESSAGE -----"
+#define PCP_SIG_START  "----- BEGIN ED25519 SIGNATURE -----"
+#define PCP_SIG_END    "------ END ED25519 SIGNATURE ------"
+#define PCP_SIGPREFIX  "\nnacl-"
 
 #define PCP_ME "Pretty Curved Privacy"
 

include/pcp/ed.h

@@ -35,6 +35,8 @@
 #include "platform.h"
 #include "mem.h"
 #include "key.h"
+#include "keyhash.h"
+#include "util.h"
 
 /* sign a message of messagesize using s->edsecret, if it works
    return message+signature (size: messagesize + crypto_sign_BYTES),
@@ -51,4 +53,6 @@ unsigned char * pcp_ed_verify(unsigned char *signature, size_t siglen, pcp_pubke
    sig only to the output */
 size_t pcp_ed_sign_buffered(FILE *in, FILE *out, pcp_key_t *s, int z85);
 
+unsigned char *pcp_ed_verify_buffered(FILE *in, pcp_pubkey_t *p);
+
 #endif // _HAVE_PCP_ED_H

include/pcp/util.h

@@ -26,13 +26,31 @@
 #define _HAVE_PCP_UTIL_H
 
 #include <ctype.h>
+#include <wctype.h>
 
+// lowercase a string
 static inline char *_lc(char *in) {
   size_t len = strlen(in);
-  int i;
+  size_t i;
   for(i=0; i<len; ++i)
     in[i] = towlower(in[i]);
   return in;
 }
 
+// find the offset of the beginning of a certain string within binary data
+static inline int _findoffset(unsigned char *bin, size_t binlen, char *sigstart, size_t hlen) {
+  size_t i;
+  int sigfoot = 181; // yes, also bad. that's the armored sig footer
+  int offset = -1;
+
+  for(i=0; i<binlen-sigfoot; ++i) {
+    if(memcmp(&bin[i], sigstart, hlen) == 0) {
+      offset = i;
+      break;
+    }
+  }
+
+  return offset;
+}
+
 #endif // _HAVE_PCP_UTIL_H

libpcp/ed.c

@@ -79,9 +79,7 @@ size_t pcp_ed_sign_buffered(FILE *in, FILE *out, pcp_key_t *s, int z85) {
   crypto_sign(signature, &mlen, hash, crypto_generichash_BYTES_MAX, s->edsecret);
 
   if(z85) {
-    if(in_buf[cur_bufsize] != '\n')
-      fprintf(out, "\n");
-    fprintf(out, "%s\nVersion: PCP v%d.%d.%d\n\n", PCP_SIG_START, PCP_VERSION_MAJOR, PCP_VERSION_MINOR, PCP_VERSION_PATCH);
+    fprintf(out, "\n%s\nVersion: PCP v%d.%d.%d\n\n", PCP_SIG_START, PCP_VERSION_MAJOR, PCP_VERSION_MINOR, PCP_VERSION_PATCH);
     size_t zlen;
     char *z85encoded = pcp_z85_encode((unsigned char*)signature, crypto_sign_BYTES, &zlen);
     fprintf(out, "%s\n%s\n", z85encoded, PCP_SIG_END);
@@ -99,3 +97,135 @@ size_t pcp_ed_sign_buffered(FILE *in, FILE *out, pcp_key_t *s, int z85) {
 
   return mlen; // ???
 }
+
+
+unsigned char *pcp_ed_verify_buffered(FILE *in, pcp_pubkey_t *p) {
+  unsigned char in_buf[PCP_BLOCK_SIZE];
+  size_t cur_bufsize = 0;
+  int z85 = 0;
+  crypto_generichash_state *st = ucmalloc(sizeof(crypto_generichash_state));
+  unsigned char hash[crypto_generichash_BYTES_MAX];
+  char *zhead;
+  size_t hlen = strlen(PCP_SIG_HEADER);
+  size_t nextsize = 0;
+  size_t restsize = 0;
+  size_t mlen = + crypto_sign_BYTES + crypto_generichash_BYTES_MAX;
+  unsigned char z85encoded[181];
+  unsigned char sighash[mlen];
+  unsigned char sig[crypto_sign_BYTES];
+  char z85sigstart[] = PCP_SIG_START;
+  char binsigstart[] = PCP_SIGPREFIX;
+  int offset = -1;
+
+  crypto_generichash_init(st, NULL, 0, 0);
+
+  // determine sig type, clear or bin
+  cur_bufsize = hlen + 14; // header + hash name + 3x newline
+  fread(&in_buf, 1, cur_bufsize, in);
+  zhead = ucmalloc(cur_bufsize);
+  memcpy(zhead, in_buf, hlen);
+  memset(&zhead[hlen], 0, 1);
+
+  if(strncmp(zhead, PCP_SIG_HEADER, hlen) == 0)
+    z85 = 1;
+  else
+    nextsize = cur_bufsize;
+  
+  while(!feof(in)) {
+    if(z85 == 0 && nextsize > 0) {
+      // bin sig, read blocksize - header and put zheader in front of it again
+      cur_bufsize = fread(&in_buf[hlen], 1, PCP_BLOCK_SIZE - hlen, in);
+      memcpy(in_buf, zhead, hlen);
+      cur_bufsize += hlen;
+    }
+    else
+      cur_bufsize = fread(&in_buf, 1, PCP_BLOCK_SIZE, in);
+
+    if(cur_bufsize <= 0)
+      break;
+
+    if(z85) {
+      // look if we need to cut something from the current block
+      offset = _findoffset(in_buf, cur_bufsize, z85sigstart, strlen(z85sigstart));
+      if(offset > 0) {
+	// we need to cut
+	restsize = cur_bufsize - offset; // the start of the armor sig
+	cur_bufsize -= restsize; // bin stuff in front of it, if any
+	memcpy(z85encoded, &in_buf[offset], restsize); // save the armor sig chunk
+      }
+    }
+    else {
+      // do the same for the bin sig
+      offset = _findoffset(in_buf, cur_bufsize, binsigstart, strlen(binsigstart));
+      if(offset > 0) {
+	// we need to cut
+	restsize = cur_bufsize - offset + strlen(binsigstart); // the start of the bin sig
+	cur_bufsize -= offset; // bin stuff in front of it, if any
+	memcpy(sighash, &in_buf[offset + strlen(binsigstart)], restsize); // save the armor sig chunk
+      }
+    }
+
+    if(offset == -1)
+      crypto_generichash_update(st, in_buf, cur_bufsize);
+  }
+
+  if(offset == -1) {
+    fatal("Error, the signature doesn't contain the ed25519 signed hash\n");
+    goto errvb1;
+  }
+
+  crypto_generichash_final(st, hash, crypto_generichash_BYTES_MAX);
+
+  // pull in the remainder
+  cur_bufsize = fread(&in_buf, 1, restsize, in);
+
+  // put hashsig together
+  if(z85) {
+    memcpy(&z85encoded[restsize], in_buf, cur_bufsize);
+    char *z85block = pcp_readz85string(z85encoded, restsize + cur_bufsize);
+    if(z85block == NULL)
+      goto errvb1;
+    size_t dstlen;
+    unsigned char *z85decoded = pcp_z85_decode(z85block, &dstlen);
+    if(dstlen != mlen) {
+      fatal("z85 decoded signature didn't result in a proper signed hash\n");
+      goto errvb1;
+    }
+    memcpy(sighash, z85decoded, mlen);
+  }
+  else {
+    memcpy(&sighash[restsize], in_buf, cur_bufsize); // FIXME: check if cur_bufsize holds enough
+  }
+
+  // huh, how did we made it til here?
+  unsigned char *verifiedhash = NULL;
+  if(p == NULL) {
+    pcphash_iteratepub(p) {
+      verifiedhash = pcp_ed_verify(sighash, mlen, p);
+      if(verifiedhash != NULL)
+	break;
+    }
+  }
+  else {
+    verifiedhash = pcp_ed_verify(sighash, mlen, p);
+  }
+
+  if(verifiedhash == NULL)
+    goto errvb1;
+
+ 
+  if(memcmp(verifiedhash, hash, crypto_generichash_BYTES_MAX) != 0) {
+    // sig verified, but the hash doesn't
+    fatal("signed hash doesn't match with actual hash of signed file content\n");
+    free(verifiedhash);
+  }
+
+  return verifiedhash;
+  
+
+ errvb1:
+  free(st);
+  free(zhead);
+  return NULL;
+}
+

src/signature.c

@@ -99,60 +99,29 @@ int pcpverify(char *infile, char *id) {
   if(id != NULL)
     HASH_FIND_STR(pcppubkey_hash, id, pub);
  
-  /*
-  if(pub == NULL) {
-    fatal("Could not find a usable public key in vault %s!\n",
-	  vault->filename);
-      goto errv3;
-  }
-  */
-
-  unsigned char *input = NULL;
-  size_t inputBufSize = 0;
-  unsigned char byte[1];
-  
-  while(!feof(in)) {
-    if(!fread(&byte, 1, 1, in))
-      break;
-    unsigned char *tmp = realloc(input, inputBufSize + 1);
-    input = tmp;
-    memmove(&input[inputBufSize], byte, 1);
-    inputBufSize ++;
-  }
-  fclose(in);
-
-  if(inputBufSize == 0) {
-    fatal("Input file is empty!\n");
-    goto errv4;
-  }
-
   if(pub != NULL) {
-    message = pcp_ed_verify(input, inputBufSize, pub);
+    message = pcp_ed_verify_buffered(in, pub);
     if(message != NULL) {
       fprintf(stderr, "Signature verified (signed by %s <%s>).\n", pub->owner, pub->mail);
     }
   }
   else {
-    pcphash_iteratepub(pub) {
-      message = pcp_ed_verify(input, inputBufSize, pub);
-      if(message != NULL) {
-	fprintf(stderr, "Signature verified (signed by %s <%s>).\n", pub->owner, pub->mail);
-	break;
-      }
+    // put public key as pub, so verify iterates over our keys
+    message = pcp_ed_verify_buffered(in, pub);
+    if(message != NULL) {
+      fprintf(stderr, "Signature verified (signed by %s <%s>).\n", pub->owner, pub->mail);
     }
   }
 
   if(message == NULL) {
-    fprintf(stderr, "Could not verify ignature\n");
+    fprintf(stderr, "Could not verify signature\n");
   }
   else
     free(message);
 
-  free(input);
   return 0;
 
  errv4:
-  free(input);
 
  errv1:
   return 1;