Merge pull request #6 from rjaeckel/master

decode optimization using unbuffered dd instead of sed

ocdec.sh

@@ -124,38 +124,31 @@ function decryptFile() {
 
   decFileKeyContent="$( openssl rc4 -d -in "$encFileKeyPath" -iv 0 -K $decUserFileShareKeyHEX )"
   decFileKeyContentHEX="$( echo -n $decFileKeyContent |od -An -tx1 |tr -dc '[:xdigit:]' )"
+  decFileKeyContentHEX=${decFileKeyContentHEX:0:64}
   # --- Get the FileKey ---
 
   # --- Decrypt the file ---
-  encFileContentsALL="$(cat "${USER}/$encFilePath")"
-  encFileContentsNOHEAD=$(echo -n "$encFileContentsALL" | sed -r 's/^HBEGIN:.+:HEND-*//')
-
-  pos=0; posc=0; encStream="";
-  # bottleneck: bash read by character is super slow
-  while IFS= read -r -n1 char; do
-    (( posc++ ))
-    if $(echo ${encStream: -24} |grep -Eq "^00iv00.{16}xx$"); then
-      plainIV=$(echo ${encStream: -24} |sed -r 's/^00iv00//;s/xx$//')
-      encStreamReady=${encStream:((posc - pos - 1)):((pos - 24))}
-      (( pos=0 ))
-
-      #echo "[::] DEBUG: " $encStreamReady with $plainIV
-      # can decrypt now
-      plainFileIVHEX=$(echo -n "$plainIV" |od -An -tx1 |tr -dc '[:xdigit:]')
-      openssl enc -AES-256-CFB -d -nosalt -base64 -A -K $decFileKeyContentHEX -iv $plainFileIVHEX -in <(echo "$encStreamReady")
-      #php -r "echo openssl_decrypt('$encStreamReady', 'AES-256-CFB', '$decFileKeyContent', false, '$plainIV');"
-    fi
-    (( pos++ ))
-    encStream="$encStream$char"
-  done <<< $encFileContentsNOHEAD
+  # OC writes the encrypted file in 8K chunks, each containing it's own iv in the end
+  chunkSize=8192
+  while read -d '' -n $chunkSize CHUNK || [ ! -z "$CHUNK" ]; do
+    #split chunk into payload an iv string (strip padding from iv)          
+    read payload iv <<<`echo $CHUNK | sed -r 's/(.*)00iv00(.{16})xx/\1 \2/'`
+    CHUNK=
+    #if [ -z $CHUNK ]; then break; fi
+    # convert base64 iv into hex
+    iv=$(echo -n "$iv" | od -An -tx1 | tr -dc '[:xdigit:]' )
+    # decode chunk
+    openssl enc -AES-256-CFB -d -nosalt -base64 -A -K $decFileKeyContentHEX -iv $iv -in <(echo "$payload")
+    #done <<<`sed -r 's/^HBEGIN:.+:HEND-*//' <"${USER}/$encFilePath"` # pipe the encrypted file without head into the loop
+    done < <(dd bs=$chunkSize skip=1 if="${USER}/$encFilePath")
   # --- Decrypt the file ---
 }
 
 # Get a username from the path (arg1)
-USER="$(echo $1 |cut -sd / -f 1)"
+USER="$(echo "$1" |cut -sd / -f 1)"
 
 # Strip off the username from the path (arg1)
-FILETD="$(echo $1 |cut -sd / -f 2-)"
+FILETD="$(echo "$1" |cut -sd / -f 2-)"
 
 if [ ! -r "$USER" ]; then
   echo "User directory cannot be found! Are you sure you are in ownCloud's data directory?"