X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/f9ba5e2255cf18092750fffacb6a9603571a2be5..51894f20e0c03113b4c4e07898ac5e955b21ec41:/src/src/pdkim/pdkim.c

diff --git a/src/src/pdkim/pdkim.c b/src/src/pdkim/pdkim.c
index 256f44088..c723ae6c8 100644
--- a/src/src/pdkim/pdkim.c
+++ b/src/src/pdkim/pdkim.c
@@ -1,8 +1,10 @@
 /*
  *  PDKIM - a RFC4871 (DKIM) implementation
  *
+ *  Copyright (c) The Exim Maintainers 2021 - 2023
+ *  Copyright (C) 2016 - 2020  Jeremy Harris <jgh@exim.org>
  *  Copyright (C) 2009 - 2016  Tom Kistner <tom@duncanthrax.net>
- *  Copyright (C) 2016 - 2018  Jeremy Harris <jgh@exim.org>
+ *  SPDX-License-Identifier: GPL-2.0-or-later
  *
  *  http://duncanthrax.net/pdkim/
  *
@@ -26,8 +28,8 @@
 
 #ifndef DISABLE_DKIM	/* entire file */
 
-#ifndef SUPPORT_TLS
-# error Need SUPPORT_TLS for DKIM
+#ifdef DISABLE_TLS
+# error Must not DISABLE_TLS, for DKIM
 #endif
 
 #include "crypt_ver.h"
@@ -71,11 +73,7 @@ const uschar * pdkim_canons[] = {
   NULL
 };
 
-typedef struct {
-  const uschar * dkim_hashname;
-  hashmethod	 exim_hashmethod;
-} pdkim_hashtype;
-static const pdkim_hashtype pdkim_hashes[] = {
+const pdkim_hashtype pdkim_hashes[] = {
   { US"sha1",   HASH_SHA1 },
   { US"sha256", HASH_SHA2_256 },
   { US"sha512", HASH_SHA2_512 }
@@ -84,7 +82,7 @@ static const pdkim_hashtype pdkim_hashes[] = {
 const uschar * pdkim_keytypes[] = {
   [KEYTYPE_RSA] =	US"rsa",
 #ifdef SIGN_HAVE_ED25519
-  [KEYTYPE_ED25519] =	US"ed25519",		/* Works for 3.6.0 GnuTLS */
+  [KEYTYPE_ED25519] =	US"ed25519",		/* Works for 3.6.0 GnuTLS, OpenSSL 1.1.1 */
 #endif
 
 #ifdef notyet_EC_dkim_extensions	/* https://tools.ietf.org/html/draft-srose-dkim-ecc-00 */
@@ -111,7 +109,7 @@ pdkim_combined_canon_entry pdkim_combined_canons[] = {
 };
 
 
-static blob lineending = {.data = US"\r\n", .len = 2};
+static const blob lineending = {.data = US"\r\n", .len = 2};
 
 /* -------------------------------------------------------------------------- */
 uschar *
@@ -125,6 +123,40 @@ return string_sprintf("%s-%s",
 }
 
 
+static int
+pdkim_keyname_to_keytype(const uschar * s)
+{
+for (int i = 0; i < nelem(pdkim_keytypes); i++)
+  if (Ustrcmp(s, pdkim_keytypes[i]) == 0) return i;
+return -1;
+}
+
+int
+pdkim_hashname_to_hashtype(const uschar * s, unsigned len)
+{
+if (!len) len = Ustrlen(s);
+for (int i = 0; i < nelem(pdkim_hashes); i++)
+  if (Ustrncmp(s, pdkim_hashes[i].dkim_hashname, len) == 0)
+    return i;
+return -1;
+}
+
+void
+pdkim_cstring_to_canons(const uschar * s, unsigned len,
+  int * canon_head, int * canon_body)
+{
+if (!len) len = Ustrlen(s);
+for (int i = 0; pdkim_combined_canons[i].str; i++)
+  if (  Ustrncmp(s, pdkim_combined_canons[i].str, len) == 0
+     && len == Ustrlen(pdkim_combined_canons[i].str))
+    {
+    *canon_head = pdkim_combined_canons[i].canon_headers;
+    *canon_body = pdkim_combined_canons[i].canon_body;
+    break;
+    }
+}
+
+
 
 const char *
 pdkim_verify_status_str(int status)
@@ -151,6 +183,7 @@ switch(ext_status)
   case PDKIM_VERIFY_INVALID_BUFFER_SIZE: return "PDKIM_VERIFY_INVALID_BUFFER_SIZE";
   case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: return "PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD";
   case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return "PDKIM_VERIFY_INVALID_PUBKEY_IMPORT";
+  case PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE: return "PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE";
   case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: return "PDKIM_VERIFY_INVALID_SIGNATURE_ERROR";
   case PDKIM_VERIFY_INVALID_DKIM_VERSION: return "PDKIM_VERIFY_INVALID_DKIM_VERSION";
   default: return "PDKIM_VERIFY_UNKNOWN";
@@ -168,6 +201,7 @@ switch(status)
   case PDKIM_ERR_RSA_SIGNING:	return US"SIGNING";
   case PDKIM_ERR_LONG_LINE:	return US"LONG_LINE";
   case PDKIM_ERR_BUFFER_TOO_SMALL:	return US"BUFFER_TOO_SMALL";
+  case PDKIM_ERR_EXCESS_SIGS:	return US"EXCESS_SIGS";
   case PDKIM_SIGN_PRIVKEY_WRAP:	return US"PRIVKEY_WRAP";
   case PDKIM_SIGN_PRIVKEY_B64D:	return US"PRIVKEY_B64D";
   default: return US"(unknown)";
@@ -177,11 +211,10 @@ switch(status)
 
 /* -------------------------------------------------------------------------- */
 /* Print debugging functions */
-static void
+void
 pdkim_quoteprint(const uschar *data, int len)
 {
-int i;
-for (i = 0; i < len; i++)
+for (int i = 0; i < len; i++)
   {
   const int c = data[i];
   switch (c)
@@ -203,11 +236,10 @@ for (i = 0; i < len; i++)
 debug_printf("\n");
 }
 
-static void
+void
 pdkim_hexprint(const uschar *data, int len)
 {
-int i;
-if (data) for (i = 0 ; i < len; i++) debug_printf("%02x", data[i]);
+if (data) for (int i = 0 ; i < len; i++) debug_printf("%02x", data[i]);
 else debug_printf("<NULL>");
 debug_printf("\n");
 }
@@ -217,7 +249,7 @@ debug_printf("\n");
 static pdkim_stringlist *
 pdkim_prepend_stringlist(pdkim_stringlist * base, const uschar * str)
 {
-pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist));
+pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist), GET_UNTAINTED);
 
 memset(new_entry, 0, sizeof(pdkim_stringlist));
 new_entry->value = string_copy(str);
@@ -302,16 +334,15 @@ return PDKIM_FAIL;
 /* -------------------------------------------------------------------------- */
 /* Performs "relaxed" canonicalization of a header. */
 
-static uschar *
-pdkim_relax_header(const uschar * header, BOOL append_crlf)
+uschar *
+pdkim_relax_header_n(const uschar * header, int len, BOOL append_crlf)
 {
 BOOL past_field_name = FALSE;
 BOOL seen_wsp = FALSE;
-const uschar * p;
-uschar * relaxed = store_get(Ustrlen(header)+3);
+uschar * relaxed = store_get(len+3, GET_TAINTED);
 uschar * q = relaxed;
 
-for (p = header; *p; p++)
+for (const uschar * p = header; p - header < len; p++)
   {
   uschar c = *p;
 
@@ -347,6 +378,13 @@ return relaxed;
 }
 
 
+uschar *
+pdkim_relax_header(const uschar * header, BOOL append_crlf)
+{
+return pdkim_relax_header_n(header, Ustrlen(header), append_crlf);
+}
+
+
 /* -------------------------------------------------------------------------- */
 #define PDKIM_QP_ERROR_DECODE -1
 
@@ -381,7 +419,7 @@ pdkim_decode_qp(const uschar * str)
 int nchar = 0;
 uschar * q;
 const uschar * p = str;
-uschar * n = store_get(Ustrlen(str)+1);
+uschar * n = store_get(Ustrlen(str)+1, GET_TAINTED);
 
 *n = '\0';
 q = n;
@@ -407,19 +445,18 @@ return n;
 
 /* -------------------------------------------------------------------------- */
 
-static void
+void
 pdkim_decode_base64(const uschar * str, blob * b)
 {
-int dlen;
-dlen = b64decode(str, &b->data);
+int dlen = b64decode(str, &b->data, str);
 if (dlen < 0) b->data = NULL;
 b->len = dlen;
 }
 
-static uschar *
+uschar *
 pdkim_encode_base64(blob * b)
 {
-return b64encode(b->data, b->len);
+return b64encode(CUS b->data, b->len);
 }
 
 
@@ -432,15 +469,14 @@ static pdkim_signature *
 pdkim_parse_sig_header(pdkim_ctx * ctx, uschar * raw_hdr)
 {
 pdkim_signature * sig;
-uschar *p, *q;
+uschar *q;
 gstring * cur_tag = NULL;
 gstring * cur_val = NULL;
 BOOL past_hname = FALSE;
 BOOL in_b_val = FALSE;
 int where = PDKIM_HDR_LIMBO;
-int i;
 
-sig = store_get(sizeof(pdkim_signature));
+sig = store_get(sizeof(pdkim_signature), GET_UNTAINTED);
 memset(sig, 0, sizeof(pdkim_signature));
 sig->bodylength = -1;
 
@@ -449,9 +485,9 @@ sig->version = 0;
 sig->keytype = -1;
 sig->hashtype = -1;
 
-q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1);
+q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1, GET_TAINTED);
 
-for (p = raw_hdr; ; p++)
+for (uschar * p = raw_hdr; ; p++)
   {
   char c = *p;
 
@@ -531,37 +567,24 @@ for (p = raw_hdr; ; p++)
 	    break;
 	  case 'a':					/* algorithm */
 	    {
-	    uschar * s = Ustrchr(cur_val->s, '-');
-
-	    for(i = 0; i < nelem(pdkim_keytypes); i++)
-	      if (Ustrncmp(cur_val->s, pdkim_keytypes[i], s - cur_val->s) == 0)
-		{ sig->keytype = i; break; }
-	    if (sig->keytype < 0)
-	      log_write(0, LOG_MAIN,
-		"DKIM: ignoring signature due to nonhandled keytype in a=%s",
-		cur_val->s);
-
-	    for (++s, i = 0; i < nelem(pdkim_hashes); i++)
-	      if (Ustrcmp(s, pdkim_hashes[i].dkim_hashname) == 0)
-		{ sig->hashtype = i; break; }
-	    if (sig->hashtype < 0)
-	      log_write(0, LOG_MAIN,
-		"DKIM: ignoring signature due to nonhandled hashtype in a=%s",
-		cur_val);
-	    break;
+	    const uschar * list = cur_val->s;
+	    int sep = '-';
+	    uschar * elem;
+
+	    if ((elem = string_nextinlist(&list, &sep, NULL, 0)))
+	      sig->keytype = pdkim_keyname_to_keytype(elem);
+	    if ((elem = string_nextinlist(&list, &sep, NULL, 0)))
+	      for (int i = 0; i < nelem(pdkim_hashes); i++)
+		if (Ustrcmp(elem, pdkim_hashes[i].dkim_hashname) == 0)
+		  { sig->hashtype = i; break; }
 	    }
 
 	  case 'c':					/* canonicalization */
-	    for (i = 0; pdkim_combined_canons[i].str; i++)
-	      if (Ustrcmp(cur_val->s, pdkim_combined_canons[i].str) == 0)
-	        {
-		sig->canon_headers = pdkim_combined_canons[i].canon_headers;
-		sig->canon_body    = pdkim_combined_canons[i].canon_body;
-		break;
-		}
+	    pdkim_cstring_to_canons(cur_val->s, 0,
+				    &sig->canon_headers, &sig->canon_body);
 	    break;
 	  case 'q':				/* Query method (for pubkey)*/
-	    for (i = 0; pdkim_querymethods[i]; i++)
+	    for (int i = 0; pdkim_querymethods[i]; i++)
 	      if (Ustrcmp(cur_val->s, pdkim_querymethods[i]) == 0)
 	        {
 		sig->querymethod = i;	/* we never actually use this */
@@ -618,15 +641,15 @@ while (--q > sig->rawsig_no_b_val  && (*q == '\r' || *q == '\n'))
 DEBUG(D_acl)
   {
   debug_printf(
-	  "PDKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
+	  "DKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
   pdkim_quoteprint(US sig->rawsig_no_b_val, Ustrlen(sig->rawsig_no_b_val));
   debug_printf(
-	  "PDKIM >> Sig size: %4u bits\n", (unsigned) sig->sighash.len*8);
+	  "DKIM >> Sig size: %4u bits\n", (unsigned) sig->sighash.len*8);
   debug_printf(
-	  "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+	  "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
   }
 
-if (!pdkim_set_bodyhash(ctx, sig))
+if (!pdkim_set_sig_bodyhash(ctx, sig))
   return NULL;
 
 return sig;
@@ -635,14 +658,14 @@ return sig;
 
 /* -------------------------------------------------------------------------- */
 
-static pdkim_pubkey *
-pdkim_parse_pubkey_record(pdkim_ctx *ctx, const uschar *raw_record)
+pdkim_pubkey *
+pdkim_parse_pubkey_record(const uschar *raw_record)
 {
 const uschar * ele;
 int sep = ';';
 pdkim_pubkey * pub;
 
-pub = store_get(sizeof(pdkim_pubkey));
+pub = store_get(sizeof(pdkim_pubkey), GET_TAINTED);
 memset(pub, 0, sizeof(pdkim_pubkey));
 
 while ((ele = string_nextinlist(&raw_record, &sep, NULL, 0)))
@@ -699,9 +722,11 @@ return NULL;
 If we have to relax the data for this sig, return our copy of it. */
 
 static blob *
-pdkim_update_ctx_bodyhash(pdkim_bodyhash * b, blob * orig_data, blob * relaxed_data)
+pdkim_update_ctx_bodyhash(pdkim_bodyhash * b, const blob * orig_data, blob * relaxed_data)
 {
-blob * canon_data = orig_data;
+const blob * canon_data = orig_data;
+size_t left;
+
 /* Defaults to simple canon (no further treatment necessary) */
 
 if (b->canon_method == PDKIM_CANON_RELAXED)
@@ -710,7 +735,6 @@ if (b->canon_method == PDKIM_CANON_RELAXED)
   if (!relaxed_data)
     {
     BOOL seen_wsp = FALSE;
-    const uschar * p, * r;
     int q = 0;
 
     /* We want to be able to free this else we allocate
@@ -721,7 +745,7 @@ if (b->canon_method == PDKIM_CANON_RELAXED)
     relaxed_data = store_malloc(sizeof(blob) + orig_data->len+1);
     relaxed_data->data = US (relaxed_data+1);
 
-    for (p = orig_data->data, r = p + orig_data->len; p < r; p++)
+    for (const uschar * p = orig_data->data, * r = p + orig_data->len; p < r; p++)
       {
       char c = *p;
       if (c == '\r')
@@ -747,16 +771,17 @@ if (b->canon_method == PDKIM_CANON_RELAXED)
   }
 
 /* Make sure we don't exceed the to-be-signed body length */
+left = canon_data->len;
 if (  b->bodylength >= 0
-   && b->signed_body_bytes + (unsigned long)canon_data->len > b->bodylength
+   && left > (unsigned long)b->bodylength - b->signed_body_bytes
    )
-  canon_data->len = b->bodylength - b->signed_body_bytes;
+  left = (unsigned long)b->bodylength - b->signed_body_bytes;
 
-if (canon_data->len > 0)
+if (left > 0)
   {
-  exim_sha_update(&b->body_hash_ctx, CUS canon_data->data, canon_data->len);
-  b->signed_body_bytes += canon_data->len;
-  DEBUG(D_acl) pdkim_quoteprint(canon_data->data, canon_data->len);
+  exim_sha_update(&b->body_hash_ctx, CUS canon_data->data, left);
+  b->signed_body_bytes += left;
+  DEBUG(D_acl) pdkim_quoteprint(canon_data->data, left);
   }
 
 return relaxed_data;
@@ -768,23 +793,25 @@ return relaxed_data;
 static void
 pdkim_finish_bodyhash(pdkim_ctx * ctx)
 {
-pdkim_bodyhash * b;
-pdkim_signature * sig;
-
-for (b = ctx->bodyhash; b; b = b->next)		/* Finish hashes */
+for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)     /* Finish hashes */
+  {
+  DEBUG(D_acl) debug_printf("DKIM: finish bodyhash %s/%s/%ld len %ld\n",
+      pdkim_hashes[b->hashtype].dkim_hashname, pdkim_canons[b->canon_method],
+      b->bodylength, b->signed_body_bytes);
   exim_sha_finish(&b->body_hash_ctx, &b->bh);
+  }
 
 /* Traverse all signatures */
-for (sig = ctx->sig; sig; sig = sig->next)
+for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next)
   {
-  b = sig->calc_body_hash;
+  pdkim_bodyhash * b = sig->calc_body_hash;
 
   DEBUG(D_acl)
     {
-    debug_printf("PDKIM [%s] Body bytes hashed: %lu\n"
-		 "PDKIM [%s] Body %s computed: ",
-		sig->domain, b->signed_body_bytes,
-		sig->domain, pdkim_hashes[sig->hashtype].dkim_hashname);
+    debug_printf("DKIM [%s]%s Body bytes (%s) hashed: %lu\n"
+		 "DKIM [%s]%s Body %s computed: ",
+	sig->domain, sig->selector, pdkim_canons[b->canon_method], b->signed_body_bytes,
+	sig->domain, sig->selector, pdkim_hashes[b->hashtype].dkim_hashname);
     pdkim_hexprint(CUS b->bh.data, b->bh.len);
     }
 
@@ -801,18 +828,18 @@ for (sig = ctx->sig; sig; sig = sig->next)
   /* VERIFICATION --------------------------------------------------------- */
   /* Be careful that the header sig included a bodyash */
 
-    if (  sig->bodyhash.data
+    if (sig->bodyhash.data && sig->bodyhash.len == b->bh.len
        && memcmp(b->bh.data, sig->bodyhash.data, b->bh.len) == 0)
       {
-      DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash verified OK\n", sig->domain);
+      DEBUG(D_acl) debug_printf("DKIM [%s] Body hash compared OK\n", sig->domain);
       }
     else
       {
       DEBUG(D_acl)
         {
-	debug_printf("PDKIM [%s] Body hash signature from headers: ", sig->domain);
+	debug_printf("DKIM [%s] Body hash signature from headers: ", sig->domain);
 	pdkim_hexprint(sig->bodyhash.data, sig->bodyhash.len);
-	debug_printf("PDKIM [%s] Body hash did NOT verify\n", sig->domain);
+	debug_printf("DKIM [%s] Body hash did NOT verify\n", sig->domain);
 	}
       sig->verify_status     = PDKIM_VERIFY_FAIL;
       sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY;
@@ -825,15 +852,13 @@ for (sig = ctx->sig; sig; sig = sig->next)
 static void
 pdkim_body_complete(pdkim_ctx * ctx)
 {
-pdkim_bodyhash * b;
-
 /* In simple body mode, if any empty lines were buffered,
 replace with one. rfc 4871 3.4.3 */
 /*XXX checking the signed-body-bytes is a gross hack; I think
 it indicates that all linebreaks should be buffered, including
 the one terminating a text line */
 
-for (b = ctx->bodyhash; b; b = b->next)
+for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
   if (  b->canon_method == PDKIM_CANON_SIMPLE
      && b->signed_body_bytes == 0
      && b->num_buffered_blanklines > 0
@@ -854,7 +879,6 @@ static void
 pdkim_bodyline_complete(pdkim_ctx * ctx)
 {
 blob line = {.data = ctx->linebuf, .len = ctx->linebuf_offset};
-pdkim_bodyhash * b;
 blob * rnl = NULL;
 blob * rline = NULL;
 
@@ -878,12 +902,13 @@ if (ctx->flags & PDKIM_DOT_TERM)
 /* Empty lines need to be buffered until we find a non-empty line */
 if (memcmp(line.data, "\r\n", 2) == 0)
   {
-  for (b = ctx->bodyhash; b; b = b->next) b->num_buffered_blanklines++;
+  for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
+    b->num_buffered_blanklines++;
   goto all_skip;
   }
 
 /* Process line for each bodyhash separately */
-for (b = ctx->bodyhash; b; b = b->next)
+for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
   {
   if (b->canon_method == PDKIM_CANON_RELAXED)
     {
@@ -932,19 +957,20 @@ return;
 static int
 pdkim_header_complete(pdkim_ctx * ctx)
 {
-pdkim_signature * sig, * last_sig;
-
-/* Special case: The last header can have an extra \r appended */
-if ( (ctx->cur_header->ptr > 1) &&
-     (ctx->cur_header->s[ctx->cur_header->ptr-1] == '\r') )
-  --ctx->cur_header->ptr;
+if (ctx->cur_header->ptr > 1)
+  gstring_trim_trailing(ctx->cur_header, '\r');
 (void) string_from_gstring(ctx->cur_header);
 
+#ifdef EXPERIMENTAL_ARC
+/* Feed the header line to ARC processing */
+(void) arc_header_feed(ctx->cur_header, !(ctx->flags & PDKIM_MODE_SIGN));
+#endif
+
 if (++ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
 
 /* SIGNING -------------------------------------------------------------- */
 if (ctx->flags & PDKIM_MODE_SIGN)
-  for (sig = ctx->sig; sig; sig = sig->next)			/* Traverse all signatures */
+  for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next)  /* Traverse all signatures */
 
     /* Add header to the signed headers list (in reverse order) */
     sig->headers = pdkim_prepend_stringlist(sig->headers, ctx->cur_header->s);
@@ -956,7 +982,7 @@ else
 #ifdef notdef
   DEBUG(D_acl)
     {
-    debug_printf("PDKIM >> raw hdr: ");
+    debug_printf("DKIM >> raw hdr: ");
     pdkim_quoteprint(CUS ctx->cur_header->s, ctx->cur_header->ptr);
     }
 #endif
@@ -964,12 +990,13 @@ else
 		  DKIM_SIGNATURE_HEADERNAME,
 		  Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0)
     {
+    pdkim_signature * sig, * last_sig;
     /* Create and chain new signature block.  We could error-check for all
     required tags here, but prefer to create the internal sig and expicitly
     fail verification of it later. */
 
     DEBUG(D_acl) debug_printf(
-	"PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
+	"DKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
 
     sig = pdkim_parse_sig_header(ctx, ctx->cur_header->s);
 
@@ -980,6 +1007,13 @@ else
       while (last_sig->next) last_sig = last_sig->next;
       last_sig->next = sig;
       }
+
+    if (dkim_collect_input && --dkim_collect_input == 0)
+      {
+      ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header->s);
+      ctx->cur_header->s[ctx->cur_header->ptr = 0] = '\0';
+      return PDKIM_ERR_EXCESS_SIGS;
+      }
     }
 
   /* all headers are stored for signature verification */
@@ -999,15 +1033,14 @@ return PDKIM_OK;
 DLLEXPORT int
 pdkim_feed(pdkim_ctx * ctx, uschar * data, int len)
 {
-int p, rc;
-
 /* Alternate EOD signal, used in non-dotstuffing mode */
 if (!data)
   pdkim_body_complete(ctx);
 
-else for (p = 0; p<len; p++)
+else for (int p = 0; p < len; p++)
   {
   uschar c = data[p];
+  int rc;
 
   if (ctx->flags & PDKIM_PAST_HDRS)
     {
@@ -1048,7 +1081,7 @@ else for (p = 0; p<len; p++)
 
 	ctx->flags = (ctx->flags & ~(PDKIM_SEEN_LF|PDKIM_SEEN_CR)) | PDKIM_PAST_HDRS;
 	DEBUG(D_acl) debug_printf(
-	    "PDKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
+	    "DKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
 	continue;
 	}
       else
@@ -1083,14 +1116,14 @@ return string_catn(str, US"\r\n\t", 3);
 
 /*
  * RFC 5322 specifies that header line length SHOULD be no more than 78
- * lets make it so!
  *  pdkim_headcat
  *
- * returns uschar * (not nul-terminated)
+ * Returns gstring (not nul-terminated) appending to one supplied
  *
  * col: this int holds and receives column number (octets since last '\n')
  * str: partial string to append to
- * pad: padding, split line or space after before or after eg: ";"
+ * pad: padding, split line or space after before or after eg: ";".
+ *               Only the initial charater is used.
  * intro: - must join to payload eg "h=", usually the tag name
  * payload: eg base64 data - long data can be split arbitrarily.
  *
@@ -1099,7 +1132,7 @@ return string_catn(str, US"\r\n\t", 3);
  * pairs and inside long values. it also always spaces or breaks after the
  * "pad"
  *
- * no guarantees are made for output given out-of range input. like tag
+ * No guarantees are made for output given out-of range input. like tag
  * names longer than 78, or bogus col. Input is assumed to be free of line breaks.
  */
 
@@ -1107,92 +1140,64 @@ static gstring *
 pdkim_headcat(int * col, gstring * str,
   const uschar * pad, const uschar * intro, const uschar * payload)
 {
-size_t l;
-
-if (pad)
-  {
-  l = Ustrlen(pad);
-  if (*col + l > 78)
-    str = pdkim_hdr_cont(str, col);
-  str = string_catn(str, pad, l);
-  *col += l;
-  }
-
-l = (pad?1:0) + (intro?Ustrlen(intro):0);
-
-if (*col + l > 78)
-  { /*can't fit intro - start a new line to make room.*/
-  str = pdkim_hdr_cont(str, col);
-  l = intro?Ustrlen(intro):0;
-  }
+int len, chomp, padded = 0;
 
-l += payload ? Ustrlen(payload):0 ;
+/* If we can fit at least the pad at the end of current line, do it now.
+Otherwise, wrap if there is a pad. */
 
-while (l>77)
-  { /* this fragment will not fit on a single line */
-  if (pad)
-    {
-    str = string_catn(str, US" ", 1);
-    *col += 1;
-    pad = NULL; /* only want this once */
-    l--;
-    }
-
-  if (intro)
-    {
-    size_t sl = Ustrlen(intro);
-
-    str = string_catn(str, intro, sl);
-    *col += sl;
-    l -= sl;
-    intro = NULL; /* only want this once */
-    }
-
-  if (payload)
+if (pad)
+  if (*col + 1 <= 78)
     {
-    size_t sl = Ustrlen(payload);
-    size_t chomp = *col+sl < 77 ? sl : 78-*col;
-
-    str = string_catn(str, payload, chomp);
-    *col += chomp;
-    payload += chomp;
-    l -= chomp-1;
+    str = string_catn(str, pad, 1);
+    (*col)++;
+    pad = NULL;
+    padded = 1;
     }
+  else
+    str = pdkim_hdr_cont(str, col);
 
-  /* the while precondition tells us it didn't fit. */
-  str = pdkim_hdr_cont(str, col);
-  }
+/* Special case: if the whole addition does not fit at the end of the current
+line, but could fit on a new line, wrap to give it its full, dedicated line.  */
 
-if (*col + l > 78)
+len = (pad ? 2 : padded)
+    + (intro ? Ustrlen(intro) : 0)
+    + (payload ? Ustrlen(payload) : 0);
+if (len <= 77 && *col+len > 78)
   {
   str = pdkim_hdr_cont(str, col);
-  pad = NULL;
+  padded = 0;
   }
 
+/* Either we already dealt with the pad or we know there is room */
+
 if (pad)
   {
+  str = string_catn(str, pad, 1);
   str = string_catn(str, US" ", 1);
-  *col += 1;
-  pad = NULL;
+  *col += 2;
   }
-
-if (intro)
+else if (padded && *col < 78)
   {
-  size_t sl = Ustrlen(intro);
-
-  str = string_catn(str, intro, sl);
-  *col += sl;
-  l -= sl;
-  intro = NULL;
+  str = string_catn(str, US" ", 1);
+  (*col)++;
   }
 
-if (payload)
-  {
-  size_t sl = Ustrlen(payload);
+/* Call recursively with intro as payload: it gets the same, special treatment
+(that is, not split if < 78).  */
 
-  str = string_catn(str, payload, sl);
-  *col += sl;
-  }
+if (intro)
+  str = pdkim_headcat(col, str, NULL, NULL, intro);
+
+if (payload)
+  for (len = Ustrlen(payload); len; len -= chomp)
+    {
+    if (*col >= 78)
+      str = pdkim_hdr_cont(str, col);
+    chomp = *col+len > 78 ? 78 - *col : len;
+    str = string_catn(str, payload, chomp);
+    *col += chomp;
+    payload += chomp;
+    }
 
 return str;
 }
@@ -1261,7 +1266,7 @@ if (sig->identity)
 
 if (sig->created > 0)
   {
-  uschar minibuf[20];
+  uschar minibuf[21];
 
   snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->created);
   hdr = pdkim_headcat(&col, hdr, US";", US"t=", minibuf);
@@ -1269,7 +1274,7 @@ if (sig->created > 0)
 
 if (sig->expires > 0)
   {
-  uschar minibuf[20];
+  uschar minibuf[21];
 
   snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires);
   hdr = pdkim_headcat(&col, hdr, US";", US"x=", minibuf);
@@ -1277,7 +1282,7 @@ if (sig->expires > 0)
 
 if (sig->bodylength >= 0)
   {
-  uschar minibuf[20];
+  uschar minibuf[21];
 
   snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength);
   hdr = pdkim_headcat(&col, hdr, US";", US"l=", minibuf);
@@ -1308,6 +1313,29 @@ return string_from_gstring(hdr);
 
 /* -------------------------------------------------------------------------- */
 
+/* According to draft-ietf-dcrup-dkim-crypto-07 "keys are 256 bits" (referring
+to DNS, hence the pubkey).  Check for more than 32 bytes; if so assume the
+alternate possible representation (still) being discussed: a
+SubjectPublickeyInfo wrapped key - and drop all but the trailing 32-bytes (it
+should be a DER, with exactly 12 leading bytes - but we could accept a BER also,
+which could be any size).  We still rely on the crypto library for checking for
+undersize.
+
+When the RFC is published this should be re-addressed. */
+
+static void
+check_bare_ed25519_pubkey(pdkim_pubkey * p)
+{
+int excess = p->key.len - 32;
+if (excess > 0)
+  {
+  DEBUG(D_acl)
+    debug_printf("DKIM: unexpected pubkey len %lu\n", (unsigned long) p->key.len);
+  p->key.data += excess; p->key.len = 32;
+  }
+}
+
+
 static pdkim_pubkey *
 pdkim_key_from_dns(pdkim_ctx * ctx, pdkim_signature * sig, ev_ctx * vctx,
   const uschar ** errstr)
@@ -1319,7 +1347,7 @@ pdkim_pubkey * p;
 
 dns_txt_name = string_sprintf("%s._domainkey.%s.", sig->selector, sig->domain);
 
-if (  !(dns_txt_reply = ctx->dns_txt_callback(CS dns_txt_name))
+if (  !(dns_txt_reply = ctx->dns_txt_callback(dns_txt_name))
    || dns_txt_reply[0] == '\0'
    )
   {
@@ -1331,14 +1359,14 @@ if (  !(dns_txt_reply = ctx->dns_txt_callback(CS dns_txt_name))
 DEBUG(D_acl)
   {
   debug_printf(
-    "PDKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"
+    "DKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"
     " %s\n"
     " Raw record: ",
     dns_txt_name);
   pdkim_quoteprint(CUS dns_txt_reply, Ustrlen(dns_txt_reply));
   }
 
-if (  !(p = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply))
+if (  !(p = pdkim_parse_pubkey_record(CUS dns_txt_reply))
    || (Ustrcmp(p->srvtype, "*") != 0 && Ustrcmp(p->srvtype, "email") != 0)
    )
   {
@@ -1352,19 +1380,36 @@ if (  !(p = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply))
     else
       debug_printf(" Error while parsing public key record\n");
     debug_printf(
-      "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+      "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
     }
   return NULL;
   }
 
 DEBUG(D_acl) debug_printf(
-      "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+      "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
 
 /* Import public key */
 
+/* Normally we use the signature a= tag to tell us the pubkey format.
+When signing under debug we do a test-import of the pubkey, and at that
+time we do not have a signature so we must interpret the pubkey k= tag
+instead.  Assume writing on the sig is ok in that case. */
+
+if (sig->keytype < 0)
+  if ((sig->keytype = pdkim_keyname_to_keytype(p->keytype)) < 0)
+    {
+    DEBUG(D_acl) debug_printf("verify_init: unhandled keytype %s\n", p->keytype);
+    sig->verify_status =      PDKIM_VERIFY_INVALID;
+    sig->verify_ext_status =  PDKIM_VERIFY_INVALID_PUBKEY_IMPORT;
+    return NULL;
+    }
+
+if (sig->keytype == KEYTYPE_ED25519)
+  check_bare_ed25519_pubkey(p);
+
 if ((*errstr = exim_dkim_verify_init(&p->key,
 	    sig->keytype == KEYTYPE_ED25519 ? KEYFMT_ED25519_BARE : KEYFMT_DER,
-	    vctx)))
+	    vctx, &sig->keybits)))
   {
   DEBUG(D_acl) debug_printf("verify_init: %s\n", *errstr);
   sig->verify_status =      PDKIM_VERIFY_INVALID;
@@ -1377,16 +1422,68 @@ return p;
 }
 
 
+/* -------------------------------------------------------------------------- */
+/* Sort and filter the sigs developed from the message */
+
+static pdkim_signature *
+sort_sig_methods(pdkim_signature * siglist)
+{
+pdkim_signature * yield, ** ss;
+const uschar * prefs;
+uschar * ele;
+int sep;
+
+if (!siglist) return NULL;
+
+/* first select in order of hashtypes */
+DEBUG(D_acl) debug_printf("DKIM: dkim_verify_hashes   '%s'\n", dkim_verify_hashes);
+for (prefs = dkim_verify_hashes, sep = 0, yield = NULL, ss = &yield;
+     ele = string_nextinlist(&prefs, &sep, NULL, 0); )
+  {
+  int i = pdkim_hashname_to_hashtype(CUS ele, 0);
+  for (pdkim_signature * s = siglist, * next, ** prev = &siglist; s;
+       s = next)
+    {
+    next = s->next;
+    if (s->hashtype == i)
+      { *prev = next; s->next = NULL; *ss = s; ss = &s->next; }
+    else
+      prev = &s->next;
+    }
+  }
+
+/* then in order of keytypes */
+siglist = yield;
+DEBUG(D_acl) debug_printf("DKIM: dkim_verify_keytypes '%s'\n", dkim_verify_keytypes);
+for (prefs = dkim_verify_keytypes, sep = 0, yield = NULL, ss = &yield;
+     ele = string_nextinlist(&prefs, &sep, NULL, 0); )
+  {
+  int i = pdkim_keyname_to_keytype(CUS ele);
+  for (pdkim_signature * s = siglist, * next, ** prev = &siglist; s;
+       s = next)
+    {
+    next = s->next;
+    if (s->keytype == i)
+      { *prev = next; s->next = NULL; *ss = s; ss = &s->next; }
+    else
+      prev = &s->next;
+    }
+  }
+
+DEBUG(D_acl) for (pdkim_signature * s = yield; s; s = s->next)
+  debug_printf(" retain d=%s s=%s a=%s\n",
+    s->domain, s->selector, dkim_sig_to_a_tag(s));
+return yield;
+}
+
+
 /* -------------------------------------------------------------------------- */
 
 DLLEXPORT int
 pdkim_feed_finish(pdkim_ctx * ctx, pdkim_signature ** return_signatures,
   const uschar ** err)
 {
-pdkim_bodyhash * b;
-pdkim_signature * sig;
 BOOL verify_pass = FALSE;
-es_ctx sctx;
 
 /* Check if we must still flush a (partial) header. If that is the
    case, the message has no body, and we must compute a body hash
@@ -1399,24 +1496,32 @@ if (ctx->cur_header && ctx->cur_header->ptr > 0)
   if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK)
     return rc;
 
-  for (b = ctx->bodyhash; b; b = b->next)
+  for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
     rnl = pdkim_update_ctx_bodyhash(b, &lineending, rnl);
   if (rnl) store_free(rnl);
   }
 else
   DEBUG(D_acl) debug_printf(
-      "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+      "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+
+/* Build (and/or evaluate) body hash.  Do this even if no DKIM sigs, in case we
+have a hash to do for ARC. */
+
+pdkim_finish_bodyhash(ctx);
+
+/* Sort and filter the recived signatures */
+
+if (!(ctx->flags & PDKIM_MODE_SIGN))
+  ctx->sig = sort_sig_methods(ctx->sig);
 
 if (!ctx->sig)
   {
-  DEBUG(D_acl) debug_printf("PDKIM: no signatures\n");
+  DEBUG(D_acl) debug_printf("DKIM: no signatures\n");
+  *return_signatures = NULL;
   return PDKIM_OK;
   }
 
-/* Build (and/or evaluate) body hash */
-pdkim_finish_bodyhash(ctx);
-
-for (sig = ctx->sig; sig; sig = sig->next)
+for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next)
   {
   hctx hhash_ctx;
   uschar * sig_hdr = US"";
@@ -1424,8 +1529,16 @@ for (sig = ctx->sig; sig; sig = sig->next)
   gstring * hdata = NULL;
   es_ctx sctx;
 
+  if (  !(ctx->flags & PDKIM_MODE_SIGN)
+     && sig->verify_status == PDKIM_VERIFY_FAIL)
+    {
+    DEBUG(D_acl)
+       debug_printf("DKIM: [%s] abandoning this signature\n", sig->domain);
+    continue;
+    }
+
   /*XXX The hash of the headers is needed for GCrypt (for which we can do RSA
-  suging only, as it happens) and for either GnuTLS and OpenSSL when we are
+  signing only, as it happens) and for either GnuTLS and OpenSSL when we are
   signing with EC (specifically, Ed25519).  The former is because the GCrypt
   signing operation is pure (does not do its own hash) so we must hash.  The
   latter is because we (stupidly, but this is what the IETF draft is saying)
@@ -1435,7 +1548,7 @@ for (sig = ctx->sig; sig; sig = sig->next)
   do this hash incrementally.
   We don't need the hash we're calculating here for the GnuTLS and OpenSSL
   cases of RSA signing, since those library routines can do hash-and-sign.
- 
+
   Some time in the future we could easily avoid doing the hash here for those
   cases (which will be common for a long while.  We could also change from
   the current copy-all-the-headers-into-one-block, then call the hash-and-sign
@@ -1448,18 +1561,19 @@ for (sig = ctx->sig; sig; sig = sig->next)
   if (!exim_sha_init(&hhash_ctx, pdkim_hashes[sig->hashtype].exim_hashmethod))
     {
     log_write(0, LOG_MAIN|LOG_PANIC,
-      "PDKIM: hash setup error, possibly nonhandled hashtype");
+      "DKIM: hash setup error, possibly nonhandled hashtype");
     break;
     }
 
   if (ctx->flags & PDKIM_MODE_SIGN)
     DEBUG(D_acl) debug_printf(
-	"PDKIM >> Headers to be signed:                            >>>>>>>>>>>>\n"
+	"DKIM >> Headers to be signed:                            >>>>>>>>>>>>\n"
 	" %s\n",
 	sig->sign_headers);
 
   DEBUG(D_acl) debug_printf(
-      "PDKIM >> Header data for hash, canonicalized, in sequence >>>>>>>>>>>>\n");
+      "DKIM >> Header data for hash, canonicalized (%-7s), in sequence >>\n",
+	pdkim_canons[sig->canon_headers]);
 
 
   /* SIGNING ---------------------------------------------------------------- */
@@ -1471,7 +1585,6 @@ for (sig = ctx->sig; sig; sig = sig->next)
   if (ctx->flags & PDKIM_MODE_SIGN)
     {
     gstring * g = NULL;
-    pdkim_stringlist *p;
     const uschar * l;
     uschar * s;
     int sep = 0;
@@ -1479,16 +1592,15 @@ for (sig = ctx->sig; sig; sig = sig->next)
     /* Import private key, including the keytype which we need for building
     the signature header  */
 
-/*XXX extend for non-RSA algos */
-    if ((*err = exim_dkim_signing_init(US sig->privkey, &sctx)))
+    if ((*err = exim_dkim_signing_init(CUS sig->privkey, &sctx)))
       {
       log_write(0, LOG_MAIN|LOG_PANIC, "signing_init: %s", *err);
       return PDKIM_ERR_RSA_PRIVKEY;
       }
     sig->keytype = sctx.keytype;
 
-    for (sig->headernames = NULL,		/* Collected signed header names */
-	  p = sig->headers; p; p = p->next)
+    sig->headernames = NULL;			/* Collected signed header names */
+    for (pdkim_stringlist * p = sig->headers; p; p = p->next)
       {
       uschar * rh = p->value;
 
@@ -1501,7 +1613,7 @@ for (sig = ctx->sig; sig; sig = sig->next)
 	  rh = pdkim_relax_header(rh, TRUE);	/* cook header for relaxed canon */
 
 	/* Feed header to the hash algorithm */
-	exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
+	exim_sha_update_string(&hhash_ctx, CUS rh);
 
 	/* Remember headers block for signing (when the library cannot do incremental)  */
 	/*XXX we could avoid doing this for all but the GnuTLS/RSA case */
@@ -1535,12 +1647,11 @@ for (sig = ctx->sig; sig; sig = sig->next)
     {
     uschar * p = sig->headernames;
     uschar * q;
-    pdkim_stringlist * hdrs;
 
     if (p)
       {
       /* clear tags */
-      for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
+      for (pdkim_stringlist * hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
 	hdrs->tag = 0;
 
       p = string_copy(p);
@@ -1550,7 +1661,7 @@ for (sig = ctx->sig; sig; sig = sig->next)
 	  *q = '\0';
 
   /*XXX walk the list of headers in same order as received. */
-	for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
+	for (pdkim_stringlist * hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
 	  if (  hdrs->tag == 0
 	     && strncasecmp(CCS hdrs->value, CCS p, Ustrlen(p)) == 0
 	     && (hdrs->value)[Ustrlen(p)] == ':'
@@ -1563,7 +1674,7 @@ for (sig = ctx->sig; sig; sig = sig->next)
 	      : string_copy(CUS hdrs->value);
 
 	    /* Feed header to the hash algorithm */
-	    exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
+	    exim_sha_update_string(&hhash_ctx, CUS rh);
 
 	    DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
 	    hdrs->tag = 1;
@@ -1579,15 +1690,15 @@ for (sig = ctx->sig; sig; sig = sig->next)
     }
 
   DEBUG(D_acl) debug_printf(
-	    "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+	    "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
 
   DEBUG(D_acl)
     {
     debug_printf(
-	    "PDKIM >> Signed DKIM-Signature header, pre-canonicalized >>>>>>>>>>>>>\n");
+	    "DKIM >> Signed DKIM-Signature header, pre-canonicalized >>>>>>>>>>>>>\n");
     pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr));
     debug_printf(
-	    "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+	    "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
     }
 
   /* Relax header if necessary */
@@ -1596,20 +1707,20 @@ for (sig = ctx->sig; sig; sig = sig->next)
 
   DEBUG(D_acl)
     {
-    debug_printf(
-	    "PDKIM >> Signed DKIM-Signature header, canonicalized >>>>>>>>>>>>>>>>>\n");
+    debug_printf("DKIM >> Signed DKIM-Signature header, canonicalized (%-7s) >>>>>>>\n",
+	    pdkim_canons[sig->canon_headers]);
     pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr));
     debug_printf(
-	    "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+	    "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
     }
 
   /* Finalize header hash */
-  exim_sha_update(&hhash_ctx, CUS sig_hdr, Ustrlen(sig_hdr));
+  exim_sha_update_string(&hhash_ctx, CUS sig_hdr);
   exim_sha_finish(&hhash_ctx, &hhash);
 
   DEBUG(D_acl)
     {
-    debug_printf("PDKIM [%s] Header %s computed: ",
+    debug_printf("DKIM [%s] Header %s computed: ",
       sig->domain, pdkim_hashes[sig->hashtype].dkim_hashname);
     pdkim_hexprint(hhash.data, hhash.len);
     }
@@ -1623,7 +1734,12 @@ for (sig = ctx->sig; sig; sig = sig->next)
   if (ctx->flags & PDKIM_MODE_SIGN)
     {
     hashmethod hm = sig->keytype == KEYTYPE_ED25519
-      ? HASH_SHA2_512 : pdkim_hashes[sig->hashtype].exim_hashmethod;
+#if defined(SIGN_OPENSSL)
+      ? HASH_NULL
+#else
+      ? HASH_SHA2_512
+#endif
+      : pdkim_hashes[sig->hashtype].exim_hashmethod;
 
 #ifdef SIGN_HAVE_ED25519
     /* For GCrypt, and for EC, we pass the hash-of-headers to the signing
@@ -1636,8 +1752,6 @@ for (sig = ctx->sig; sig; sig = sig->next)
       hhash.len = hdata->ptr;
       }
 
-/*XXX extend for non-RSA algos */
-/*- done for GnuTLS */
     if ((*err = exim_dkim_sign(&sctx, hm, &hhash, &sig->sighash)))
       {
       log_write(0, LOG_MAIN|LOG_PANIC, "signing: %s", *err);
@@ -1646,7 +1760,7 @@ for (sig = ctx->sig; sig; sig = sig->next)
 
     DEBUG(D_acl)
       {
-      debug_printf( "PDKIM [%s] b computed: ", sig->domain);
+      debug_printf( "DKIM [%s] b computed: ", sig->domain);
       pdkim_hexprint(sig->sighash.data, sig->sighash.len);
       }
 
@@ -1657,6 +1771,7 @@ for (sig = ctx->sig; sig; sig = sig->next)
   else
     {
     ev_ctx vctx;
+    hashmethod hm;
 
     /* Make sure we have all required signature tags */
     if (!(  sig->domain        && *sig->domain
@@ -1673,8 +1788,16 @@ for (sig = ctx->sig; sig; sig = sig->next)
       sig->verify_ext_status = PDKIM_VERIFY_INVALID_SIGNATURE_ERROR;
 
       DEBUG(D_acl) debug_printf(
-	  " Error in DKIM-Signature header: tags missing or invalid\n"
-	  "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+	  " Error in DKIM-Signature header: tags missing or invalid (%s)\n"
+	  "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n",
+	  !(sig->domain && *sig->domain) ? "d="
+	  : !(sig->selector && *sig->selector) ? "s="
+	  : !(sig->headernames && *sig->headernames) ? "h="
+	  : !sig->bodyhash.data ? "bh="
+	  : !sig->sighash.data ? "b="
+	  : sig->keytype < 0 || sig->hashtype < 0 ? "a="
+	  : "v="
+	  );
       goto NEXT_VERIFY;
       }
 
@@ -1686,19 +1809,19 @@ for (sig = ctx->sig; sig; sig = sig->next)
 
       DEBUG(D_acl) debug_printf(
           " Error in DKIM-Signature header: unsupported DKIM version\n"
-          "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+          "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
       goto NEXT_VERIFY;
       }
 
     DEBUG(D_acl)
       {
-      debug_printf( "PDKIM [%s] b from mail: ", sig->domain);
+      debug_printf( "DKIM [%s] b from mail: ", sig->domain);
       pdkim_hexprint(sig->sighash.data, sig->sighash.len);
       }
 
     if (!(sig->pubkey = pdkim_key_from_dns(ctx, sig, &vctx, err)))
       {
-      log_write(0, LOG_MAIN, "PDKIM: %s%s %s%s [failed key import]",
+      log_write(0, LOG_MAIN, "DKIM: %s%s %s%s [failed key import]",
 	sig->domain   ? "d=" : "", sig->domain   ? sig->domain   : US"",
 	sig->selector ? "s=" : "", sig->selector ? sig->selector : US"");
       goto NEXT_VERIFY;
@@ -1725,18 +1848,36 @@ for (sig = ctx->sig; sig; sig = sig->next)
 	}
       }
 
+    hm = sig->keytype == KEYTYPE_ED25519
+#if defined(SIGN_OPENSSL)
+      ? HASH_NULL
+#else
+      ? HASH_SHA2_512
+#endif
+      : pdkim_hashes[sig->hashtype].exim_hashmethod;
+
     /* Check the signature */
-/*XXX extend for non-RSA algos */
-/*- done for GnuTLS */
-    if ((*err = exim_dkim_verify(&vctx,
-				pdkim_hashes[sig->hashtype].exim_hashmethod,
-				&hhash, &sig->sighash)))
+
+    if ((*err = exim_dkim_verify(&vctx, hm, &hhash, &sig->sighash)))
       {
       DEBUG(D_acl) debug_printf("headers verify: %s\n", *err);
       sig->verify_status =      PDKIM_VERIFY_FAIL;
       sig->verify_ext_status =  PDKIM_VERIFY_FAIL_MESSAGE;
       goto NEXT_VERIFY;
       }
+    if (*dkim_verify_min_keysizes)
+      {
+      unsigned minbits;
+      const uschar * ss = expand_getkeyed(US pdkim_keytypes[sig->keytype],
+				    dkim_verify_min_keysizes);
+      if (ss &&  (minbits = atoi(CCS ss)) > sig->keybits)
+	{
+	DEBUG(D_acl) debug_printf("Key too short: Actual: %s %u  Minima '%s'\n",
+	  pdkim_keytypes[sig->keytype], sig->keybits, dkim_verify_min_keysizes);
+	sig->verify_status =      PDKIM_VERIFY_FAIL;
+	sig->verify_ext_status =  PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE;
+	}
+      }
 
 
     /* We have a winner! (if bodyhash was correct earlier) */
@@ -1744,13 +1885,14 @@ for (sig = ctx->sig; sig; sig = sig->next)
       {
       sig->verify_status = PDKIM_VERIFY_PASS;
       verify_pass = TRUE;
+      if (dkim_verify_minimal) break;
       }
 
 NEXT_VERIFY:
 
     DEBUG(D_acl)
       {
-      debug_printf("PDKIM [%s] %s signature status: %s",
+      debug_printf("DKIM [%s] %s signature status: %s",
 	      sig->domain, dkim_sig_to_a_tag(sig),
 	      pdkim_verify_status_str(sig->verify_status));
       if (sig->verify_ext_status > 0)
@@ -1774,16 +1916,18 @@ return ctx->flags & PDKIM_MODE_SIGN  ||  verify_pass
 /* -------------------------------------------------------------------------- */
 
 DLLEXPORT pdkim_ctx *
-pdkim_init_verify(uschar * (*dns_txt_callback)(char *), BOOL dot_stuffing)
+pdkim_init_verify(uschar * (*dns_txt_callback)(const uschar *), BOOL dot_stuffing)
 {
 pdkim_ctx * ctx;
 
-ctx = store_get(sizeof(pdkim_ctx));
+ctx = store_get(sizeof(pdkim_ctx), GET_UNTAINTED);
 memset(ctx, 0, sizeof(pdkim_ctx));
 
 if (dot_stuffing) ctx->flags = PDKIM_DOT_TERM;
-ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
+/* The line-buffer is for message data, hence tainted */
+ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN, GET_TAINTED);
 ctx->dns_txt_callback = dns_txt_callback;
+ctx->cur_header = string_get_tainted(36, GET_TAINTED);
 
 return ctx;
 }
@@ -1804,7 +1948,7 @@ if (!domain || !selector || !privkey)
 
 /* Allocate & init one signature struct */
 
-sig = store_get(sizeof(pdkim_signature));
+sig = store_get(sizeof(pdkim_signature), GET_UNTAINTED);
 memset(sig, 0, sizeof(pdkim_signature));
 
 sig->bodylength = -1;
@@ -1820,7 +1964,7 @@ for (hashtype = 0; hashtype < nelem(pdkim_hashes); hashtype++)
 if (hashtype >= nelem(pdkim_hashes))
   {
   log_write(0, LOG_MAIN|LOG_PANIC,
-    "PDKIM: unrecognised hashname '%s'", hashname);
+    "DKIM: unrecognised hashname '%s'", hashname);
   return NULL;
   }
 
@@ -1829,10 +1973,10 @@ DEBUG(D_acl)
   pdkim_signature s = *sig;
   ev_ctx vctx;
 
-  debug_printf("PDKIM (checking verify key)>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
+  debug_printf("DKIM (checking verify key)>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
   if (!pdkim_key_from_dns(ctx, &s, &vctx, errstr))
     debug_printf("WARNING: bad dkim key in dns\n");
-  debug_printf("PDKIM (finished checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+  debug_printf("DKIM (finished checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
   }
 return sig;
 }
@@ -1868,39 +2012,60 @@ return;
 
 
 /* Set up a blob for calculating the bodyhash according to the
-needs of this signature.  Use an existing one if possible, or
-create a new one.
+given needs.  Use an existing one if possible, or create a new one.
 
-Return: hashblob pointer, or NULL on error (only used as a boolean).
+Return: hashblob pointer, or NULL on error
 */
 pdkim_bodyhash *
-pdkim_set_bodyhash(pdkim_ctx * ctx, pdkim_signature * sig)
+pdkim_set_bodyhash(pdkim_ctx * ctx, int hashtype, int canon_method,
+	long bodylength)
 {
 pdkim_bodyhash * b;
 
+if (hashtype == -1 || canon_method == -1) return NULL;
+
 for (b = ctx->bodyhash; b; b = b->next)
-  if (  sig->hashtype == b->hashtype
-     && sig->canon_body == b->canon_method
-     && sig->bodylength == b->bodylength)
-    goto old;
+  if (  hashtype == b->hashtype
+     && canon_method == b->canon_method
+     && bodylength == b->bodylength)
+    {
+    DEBUG(D_receive) debug_printf("DKIM: using existing bodyhash %s/%s/%ld\n",
+      pdkim_hashes[hashtype].dkim_hashname, pdkim_canons[canon_method], bodylength);
+    return b;
+    }
 
-b = store_get(sizeof(pdkim_bodyhash));
+DEBUG(D_receive) debug_printf("DKIM: new bodyhash %s/%s/%ld\n",
+    pdkim_hashes[hashtype].dkim_hashname, pdkim_canons[canon_method], bodylength);
+b = store_get(sizeof(pdkim_bodyhash), GET_UNTAINTED);
 b->next = ctx->bodyhash;
-b->hashtype = sig->hashtype;
-b->canon_method = sig->canon_body;
-b->bodylength = sig->bodylength;
+b->hashtype = hashtype;
+b->canon_method = canon_method;
+b->bodylength = bodylength;
 if (!exim_sha_init(&b->body_hash_ctx,		/*XXX hash method: extend for sha512 */
-		  pdkim_hashes[sig->hashtype].exim_hashmethod))
+		  pdkim_hashes[hashtype].exim_hashmethod))
   {
   DEBUG(D_acl)
-    debug_printf("PDKIM: hash init error, possibly nonhandled hashtype\n");
+    debug_printf("DKIM: hash init error, possibly nonhandled hashtype\n");
   return NULL;
   }
 b->signed_body_bytes = 0;
 b->num_buffered_blanklines = 0;
 ctx->bodyhash = b;
+return b;
+}
+
 
-old:
+/* Set up a blob for calculating the bodyhash according to the
+needs of this signature.  Use an existing one if possible, or
+create a new one.
+
+Return: hashblob pointer, or NULL on error (only used as a boolean).
+*/
+pdkim_bodyhash *
+pdkim_set_sig_bodyhash(pdkim_ctx * ctx, pdkim_signature * sig)
+{
+pdkim_bodyhash * b = pdkim_set_bodyhash(ctx,
+			sig->hashtype, sig->canon_body, sig->bodylength);
 sig->calc_body_hash = b;
 return b;
 }
@@ -1911,11 +2076,12 @@ return b;
 
 void
 pdkim_init_context(pdkim_ctx * ctx, BOOL dot_stuffed,
-  uschar * (*dns_txt_callback)(char *))
+  uschar * (*dns_txt_callback)(const uschar *))
 {
 memset(ctx, 0, sizeof(pdkim_ctx));
 ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN;
-ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
+/* The line buffer is for message data, hence tainted */
+ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN, GET_TAINTED);
 DEBUG(D_acl) ctx->dns_txt_callback = dns_txt_callback;
 }