diff -uNr a/ffa/MANIFEST.TXT b/ffa/MANIFEST.TXT
--- a/ffa/MANIFEST.TXT fc1bdea6ee6bf8bb8c53a2012690cf585f482216a44fc7e0aaad542064a9f1b0c9f6f060cb539dda8b54759544a7f12aa87ac46121628a02eb3a43711741cb17
+++ b/ffa/MANIFEST.TXT e4fa89865bad0ea9b29e23b5ebb420afac679f375eb6d093a1118c7018d70709071117b4656bb9a7f817353b22ad8e668a89763c74e399ae7fc38ca70aad9f34
@@ -24,3 +24,4 @@
  612828 ffa_ch20d_litmus_nested_fix    "Fix for bug where nested 'clearsigned' sigs were rejected."
  629424 ffa_ch21a_bis_fix_ch15_gcd     "Fix for lethal flaw in Ch.15's Greatest Common Divisor."
  659788 ffa_ch21a_ter_ch14_ch20_errata "Fix for false alarm in Ch.14; Removal of two mutually-canceling bugs in Litmus."
+ 837101 ffa_litmus_width_fix_and_posix "Support for short signatures in Litmus and POSIX compatibility."
diff -uNr a/ffa/contrib/litmus/litmus.sh b/ffa/contrib/litmus/litmus.sh
--- a/ffa/contrib/litmus/litmus.sh f0d41124d72a3b364f70ea8dd1f9a434230f9ba965c89c3c48dd78071d7ac59c68ba407ef4818f326339bce5a3261c5ba10b8de8612e7c0778513b928e681988
+++ b/ffa/contrib/litmus/litmus.sh c5f8ace09860fa82446b4d3201c71975f5d2726881f1caaa6c5b9e763f11e91551eac60a5f759ece2b89609d2d4e87ab5faee0b74c88db687e20afa76975676c
@@ -40,7 +40,7 @@
 RET_BAD_SIG=1
 
 # All Other Cases:
-RET_EGGOG=-1
+RET_EGGOG=255
 
 # Verify that all of the necessary external programs in fact exist:
 for i in $EXTERNALS
@@ -155,8 +155,9 @@
 PEH_RNG_DEV="/dev/random"
 
 # Verify that each of the given input files exists:
-FILES=($PUBFILE $SIGFILE $DATAFILE)
-for f in ${FILES[@]}; do
+FILES="$PUBFILE $SIGFILE $DATAFILE"
+for f in $FILES
+do
     if ! [ -f $f ]; then
         echo "$f does not exist!" >&2
         exit $RET_EGGOG
@@ -195,7 +196,7 @@
     peh_life=$(($tape_len * 2))
     
     # Execute the tape:
-    peh_res=$((cat $PUBFILE; echo $tape) | \
+    peh_res=$(echo $tape | cat $PUBFILE - | \
         peh $peh_width $peh_height $tape_len $peh_life $PEH_RNG_DEV);
     peh_code=$?
 
@@ -232,7 +233,7 @@
 end_ln=$(grep -m 1 -n "$END_MARKER" $SIGFILE | cut -d ':' -f1)
 
 # Both start and end markers must exist :
-if [ "$start_ln" == "" ] || [ "$end_ln" == "" ]
+if [ "$start_ln" = "" ] || [ "$end_ln" = "" ]
 then
     echo "$SIGFILE does not contain ASCII-armoured PGP Signature!" >&2
     exit $RET_EGGOG
@@ -259,7 +260,7 @@
 fi
 
 # Obtain the sig bytes:
-sig_bytes=($(echo $sig_payload | base64 -d | hexdump -ve '1/1 "%.2x "'))
+sig_bytes=$(echo $sig_payload | base64 -d | hexdump -ve '1/1 "%.2x "')
 
 # If eggog -- abort:
 if [ $? -ne 0 ]
@@ -270,14 +271,14 @@
 # If we are operating on a 'clearsigned' text file, $DATAFILE will be
 # an empty temporary file, and the payload is to be extracted to it,
 # with certain munges (see http://tools.ietf.org/html/rfc4880#section-7.1)
-if [ $CLEARSIGN_MODE == true ]
+if [ $CLEARSIGN_MODE = true ]
 then
     # Find position of 'clearsign' payload start marker:
     CLEAR_MARKER="^\-\-\-\-\-BEGIN PGP SIGNED MESSAGE\-\-\-\-\-"
     start_clr=$(grep -m 1 -n "$CLEAR_MARKER" $SIGFILE | cut -d ':' -f1)
     
     # If payload start marker was not found:
-    if [ "$start_clr" == "" ]
+    if [ "$start_clr" = "" ]
     then
         eggog_broken_clearsigned
     fi
@@ -316,7 +317,7 @@
 
 
 # Number of bytes in the sig file
-sig_len=${#sig_bytes[@]}
+sig_len=$(echo $sig_bytes | wc -w)
 
 
 # Test that certain fields in the Sig have their mandatory value
@@ -342,7 +343,8 @@
     count=$1
 
     # Result: $count bytes from current $sig_pos (contiguous hex string)
-    r=$(echo ${sig_bytes[@]:$sig_pos:$count} | sed "s/ //g" | tr 'a-z' 'A-Z')
+    r=$(echo $sig_bytes | cut -d\  -f$(($sig_pos + 1))-$(($sig_pos + $count)) \
+            | sed "s/ //g" | tr 'a-z' 'A-Z')
 
     # Advance $sig_pos by $count:
     sig_pos=$(($sig_pos + $count))
@@ -357,7 +359,7 @@
 
 # Convert the current sig component to integer
 hex_to_int() {
-    r=$((16#$r))
+    r=$((0x$r))
 }
 
 # Turd to be composed of certain values from the sig, per RFC4880.
@@ -378,26 +380,26 @@
 
 # Version (only Version 4 -- what GPG 1.4.x outputs -- is supported)
 get_sig_bytes 1
-turd+=$r
+turd="${turd}${r}"
 sig_version=$r
 sig_field_mandatory "Version" $sig_version 04
 
 # Class (must be 'detached' or 'clearsign')
 get_sig_bytes 1
-turd+=$r
+turd="${turd}${r}"
 hex_to_int
 sig_class=$r
 sig_field_mandatory "Class" $sig_class $expect_sig_class
 
 # Public Key Algo (only RSA is supported)
 get_sig_bytes 1
-turd+=$r
+turd="${turd}${r}"
 sig_pk_algo=$r
 sig_field_mandatory "Public Key Algo" $sig_pk_algo 01
 
 # Digest Algo (only certain hash algos are supported)
 get_sig_bytes 1
-turd+=$r
+turd="${turd}${r}"
 hex_to_int
 sig_digest_algo=$r
 
@@ -461,13 +463,13 @@
 
 # Hashed Section Length
 get_sig_bytes 2
-turd+=$r
+turd="${turd}${r}"
 hex_to_int
 sig_hashed_len=$r
 
 # Hashed Section (typically: timestamp)
 get_sig_bytes $sig_hashed_len
-turd+=$r
+turd="${turd}${r}"
 sig_hashed=$r
 
 # Unhashed Section Length
@@ -482,12 +484,10 @@
 hashed_header_len=$((${#turd} / 2))
 
 # Final section of the hashed turd (not counted in hashed_header_len)
-turd+=$sig_version
-turd+="FF"
-turd+=$(printf "%08x" $hashed_header_len)
+turd="${turd}${sig_version}FF$(printf "%08x" $hashed_header_len)"
 
 # Compute the hash of data file and the hashed appendix from sig :
-hash=$((cat $DATAFILE; xxd -r -p <<< $turd) | $HASHER | cut -d ' ' -f1)
+hash=$(echo $turd | xxd -r -p | cat $DATAFILE - | $HASHER | cut -d ' ' -f1)
 # Convert to upper case
 hash=$(echo $hash | tr 'a-z' 'A-Z')
 
@@ -517,7 +517,12 @@
 rsa_byteness=$((($rsa_bitness + 7) / 8))
 
 # RSA Bitness for use in determining required Peh width:
-rsa_width=$(($rsa_byteness * 8))
+rsa_width=$((rsa_bitness - 1))
+rsa_width=$((rsa_width | rsa_width >> 1))
+rsa_width=$((rsa_width | rsa_width >> 2))
+rsa_width=$((rsa_width | rsa_width >> 4))
+rsa_width=$((rsa_width | rsa_width >> 8))
+rsa_width=$((rsa_width + 1))
 
 # Only traditional GPG RSA widths are supported:
 if [ $rsa_width != 2048 ] && [ $rsa_width != 4096 ] && [ $rsa_width != 8192 ]
@@ -538,21 +543,23 @@
 pkcs="0001"
 
 # Compute necessary number of padding FF bytes :
-pkcs_pad_bytes=$(($rsa_byteness - $MD_LEN - $ASN_LEN - 3))
+pkcs_pad_bytes=$(($rsa_width / 8 - $MD_LEN - $ASN_LEN - 3))
 
 # Attach the padding bytes:
-for ((x=1; x<=$pkcs_pad_bytes; x++)); do
-    pkcs+="FF"
+x=1
+while [ $x -le $pkcs_pad_bytes ]; do
+    pkcs="${pkcs}FF"
+    x=$((x + 1))
 done
 
 # Attach the 00 separator between the padding and the ASN:
-pkcs+="00"
+pkcs="${pkcs}00"
 
 # Attach the ASN ('magic' corresponding to the hash algo) :
-pkcs+=$ASN
+pkcs="${pkcs}${ASN}"
 
 # Finally, attach the computed (from Data file) hash itself :
-pkcs+=$hash
+pkcs="${pkcs}${hash}"
 
 # Generate a Peh tape which will attempt to verify $rsa_sig against the pubkey,
 # computing the expression $rsa_sig ^ PUB_E mod PUB_M and comparing to $pkcs.
@@ -564,7 +571,7 @@
 
 # 'Belt and suspenders' -- test both output and return code:
 # If verification succeeded, return code will be 1, and output 'Valid':
-if [ $peh_code -eq $PEH_YES ] && [ "$peh_res" == "Valid" ]
+if [ $peh_code -eq $PEH_YES ] && [ "$peh_res" = "Valid" ]
 then
     # Valid RSA signature:
     done_sig_valid