126 lines
4.4 KiB
Bash
Executable File
126 lines
4.4 KiB
Bash
Executable File
#!/bin/sh
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# Unpacker for DPT pkg
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# HappyZ
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# Thanks to anonymous contributer somewhere on earth
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# PKG FILE FORMAT
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# byte 1--4: DPUP - file recognizer
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# byte 5--8: data offset location A
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# byte 9--12: total data content size D
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# byte 13--16: nothing
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# byte 17--20: sigfile size B
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# byte 21--(20+B): sigfile data
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# byte (21+(-B%16)%16)--(25+(-B%16)%16): encrypted data aes key size (BE) C
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# byte (+1)--(+C): encrypted data aes key bytes
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# byte (+1)--(+32): initial vector --- up till now bytes shall equal to A
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# byte (A+1)--(A+D): encrypted data
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# byte (+1)--(+4): animation header size E
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# byte (+1)--(+4): animation data size F
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# byte (+1)--(+4): animation sigfile size G
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# byte (+1)--(+(-G%16)%16): animation sigfile --- here bytes shall be A+D+E
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# byte (A+D+E+1)--(A+D+E+F): animation data
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# zipped data format
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# FwUpdater
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# |- boot.img
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# |- boot.img.md5
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# |- system.img
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# |- system.img.md5
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# |- eufwupdater.sh
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# |- ...
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# params
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PKGFILE=$1 # pkg file
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OUTDIR=$2 # output folder
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SHA256KEY="./key.pub"
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DATAKEY_D="./key.private"
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# predefined outputs
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SIGFILE="$OUTDIR/signature"
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AESFILE="$OUTDIR/aes.key"
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IVFILE="$OUTDIR/init_vector"
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SIGFILE_ANIM="$OUTDIR/signature_animation"
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# commands
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ODUMP="od -A n -t d4 -v"
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# check if output folder does not exist, make one
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if [[ ! -d $OUTDIR ]]; then
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mkdir $OUTDIR;
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fi
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if [[ ! -d $OUTDIR ]]; then # check again
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echo "! Err: looks like we cannot create this folder"
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exit 0
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fi
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echo "* file header check.."
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if [ $(head -c 4 $PKGFILE) != "DPUP" ]; then
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echo "! Err: this seems to be an invalid pkg"
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exit 0
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fi
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echo "* getting data block size"
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OFFSET_DATA=`dd if=$PKGFILE bs=4 skip=1 count=1 2>/dev/null | $ODUMP`
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DATA_SIZE=`dd if=$PKGFILE bs=4 skip=2 count=1 2>/dev/null | $ODUMP`
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echo "* extract signature.."
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SIG_SIZE=`dd if=$PKGFILE bs=4 skip=4 count=1 2>/dev/null | $ODUMP`
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dd if=$PKGFILE of=$SIGFILE bs=1 skip=20 count=$((SIG_SIZE)) 2>/dev/null
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echo "* verify data with signature.."
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dd if=$PKGFILE bs=$((OFFSET_DATA)) skip=1 2>/dev/null | head -c $((DATA_SIZE)) | openssl dgst -sha256 -verify $SHA256KEY -signature $SIGFILE 1>/dev/null
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# if [ $? -ne 0 ]; then
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# echo "! Err: failed to verify data with provided signature"
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# exit 0
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# fi
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echo "* get encrypted data aes key.."
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OFFSET_DATAKEY_E=$((20 + SIG_SIZE + ((-(SIG_SIZE % 16)) % 16)))
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DATAKEY_E_SIZE=`dd if=$PKGFILE bs=1 skip=$OFFSET_DATAKEY_E count=4 2>/dev/null | $ODUMP`
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OFFSET_DATAKEY_E=$((OFFSET_DATAKEY_E + 4))
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echo "** decrypt it via $DATAKEY_D"
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dd if=$PKGFILE bs=1 skip=$OFFSET_DATAKEY_E count=$((DATAKEY_E_SIZE)) 2>/dev/null | openssl rsautl -decrypt -inkey $DATAKEY_D > $AESFILE
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echo "* extract 32-byte initial vector.."
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OFFSET_IV=$((OFFSET_DATAKEY_E + DATAKEY_E_SIZE))
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dd if=$PKGFILE of=$IVFILE bs=1 skip=$OFFSET_IV count=32 2>/dev/null
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echo "* decrypt data to zipped tar.."
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dd if=$PKGFILE bs=$((OFFSET_DATA)) skip=1 2>/dev/null | head -c $((DATA_SIZE)) | openssl enc -d -aes-256-cbc -K `cat $AESFILE` -iv `cat $IVFILE` > $OUTDIR/decrypted_pkg.tar.gz
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echo "* unzip data.."
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tar -xzf $OUTDIR/decrypted_pkg.tar.gz -C $OUTDIR
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echo "* checking if animation data followed by.."
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OFFSET_ANIM_HEADER=$((OFFSET_DATA + DATA_SIZE))
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ANIM_HEADER_SIZE=`dd if=$PKGFILE bs=1 skip=$OFFSET_ANIM_HEADER count=4 2>/dev/null | $ODUMP`
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if [ -z "$ANIM_HEADER_SIZE" ]; then
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ANIM_HEADER_SIZE=0
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fi
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if [[ $((ANIM_HEADER_SIZE)) -gt 0 ]]; then
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echo "** found animation block, getting animation data size.."
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ANIM_DATA_SIZE=`dd if=$PKGFILE bs=1 skip=$((OFFSET_ANIM_HEADER + 4)) count=4 2>/dev/null | $ODUMP`
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echo "** get animation signature.."
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ANIM_SIG_SIZE=`dd if=$PKGFILE bs=1 skip=$((OFFSET_ANIM_HEADER + 8)) count=4 2>/dev/null | $ODUMP`
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dd if=$PKGFILE of=$SIGFILE_ANIM bs=1 skip=$((OFFSET_ANIM_HEADER + 12)) count=$(($ANIM_SIG_SIZE)) 2>/dev/null
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echo "** verify animation data with signature.."
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OFFSET_ANIM_DATA=$((OFFSET_ANIM_HEADER + ANIM_HEADER_SIZE))
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dd if=$PKGFILE bs=$((OFFSET_ANIM_DATA)) skip=1 2>/dev/null | head -c $((ANIM_DATA_SIZE)) | openssl dgst -sha256 -verify $SHA256KEY -signature $SIGFILE_ANIM
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if [ $? -ne 0 ]; then
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echo "! Err: failed to verify animation data with provided signature"
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exit 0
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fi
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echo "** dump animation data to zipped tar.."
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dd if=$PKGFILE bs=$((OFFSET_ANIM_DATA)) skip=1 2>/dev/null > $OUTDIR/decrypted_animation_pkg.tar.gz
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echo "** unzip the tar.."
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tar -xzf $OUTDIR/decrypted_animation_pkg.tar.gz -C $OUTDIR
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fi
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