diff --git a/scripts/rename.pl b/scripts/rename.pl
new file mode 100755
index 0000000..8489580
--- /dev/null
+++ b/scripts/rename.pl
@@ -0,0 +1,94 @@
+#!/usr/bin/perl
+
+# rename identifiers (functions, types, enum constant, etc)
+# on upgrades of major version according to a list
+
+use warnings;
+use strict;
+
+use utf8;
+use open qw(:std utf8);
+
+my $usage = "Usage: $0 [-f datafile] [-s] [--] [filenames...]\n";
+
+(my $datafile = $0) =~ s/(rename-1\.3-2\.0)\.pl$/data_files\/$1.txt/;
+my $do_strings = 0;
+
+while( @ARGV && $ARGV[0] =~ /^-/ ) {
+    my $opt = shift;
+    if( $opt eq '--' ) {
+        last;
+    } elsif( $opt eq '-f' ) {
+        $datafile = shift;
+    } elsif( $opt eq '-s' ) {
+        $do_strings = 1; shift;
+    } else {
+        die $usage;
+    }
+}
+
+open my $nfh, '<', $datafile or die "Could not read $datafile\n";
+my @names = <$nfh>;
+close $nfh or die;
+
+my %subst;
+for my $name (@names) {
+    chomp $name;
+    my ($old, $new) = split / /, $name;
+    $subst{$old} = $new;
+}
+
+my $string = qr/".*?(?<!\\)"/;
+my $space = qr/\s+/;
+my $idnum = qr/[a-zA-Z0-9_]+/;
+my $symbols = qr/[!#%&'()*+,-.:;<=>?@^_`{|}~\$\/\[\\\]]+|"/;
+
+# if we replace inside strings, we don't consider them a token
+my $token = $do_strings ?         qr/$space|$idnum|$symbols/
+                        : qr/$string|$space|$idnum|$symbols/;
+
+my %warnings;
+
+while( my $filename = shift )
+{
+    print STDERR "$filename... ";
+    if( -d $filename ) { print STDERR "skip (directory)\n"; next }
+
+    open my $rfh, '<', $filename or die;
+    my @lines = <$rfh>;
+    close $rfh or die;
+
+    my @out;
+    for my $line (@lines) {
+        if( $line =~ /#include/ ) {
+            $line =~ s/polarssl/mbedtls/;
+            $line =~ s/POLARSSL/MBEDTLS/;
+            push( @out, $line );
+            next;
+        }
+
+        my @words = ($line =~ /$token/g);
+        my $checkline = join '', @words;
+        if( $checkline eq $line ) {
+            my @new = map { exists $subst{$_} ? $subst{$_} : $_ } @words;
+            push( @out, join '', @new );
+        } else {
+            $warnings{$filename} = [] unless $warnings{$filename};
+            push @{ $warnings{$filename} }, $line;
+            push( @out, $line );
+        }
+    }
+
+    open my $wfh, '>', $filename or die;
+    print $wfh $_ for @out;
+    close $wfh or die;
+    print STDERR "done\n";
+}
+
+if( %warnings ) {
+    print "\nWarning: lines skipped due to unexpected charaacters:\n";
+    for my $filename (sort keys %warnings) {
+        print "in $filename:\n";
+        print for @{ $warnings{$filename} };
+    }
+}