Use a separate symmetric key per packfile (REPO FORMAT CHANGE)
A separate key per pack is simpler and costs us very little; with repack changes later it will be possible to change keys regularly.
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36
README.rst
36
README.rst
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@ -24,7 +24,7 @@ Example use::
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git push cryptremote master
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> gcrypt: Setting up new repository at ssh://example.com:repo
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> gcrypt: Repository ID is KNBr0wKzct52
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> gcrypt: Repository URL is gcrypt::ssh://example.com:repo/G/KNBr0wKzct52
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> gcrypt: Repository URL is gcrypt::ssh://example.com:repo/G.KNBr0wKzct52
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> gcrypt: (configuration for cryptremote updated)
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> [ more lines .. ]
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> To gcrypt::[...]
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@ -70,37 +70,35 @@ Repository Format
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Encrypt(K,X) is symmetric encryption
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Hash(X) is SHA-224
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K: master key, generated once, 128 bytes
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B: branch list
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L: list of packfile hashes
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L: list of the hash (Hi) and key (Ki) for each packfile
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R: Hash(Repository ID)
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Store Manifest as EncSign(K || B || L || R) in filename R
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Each packfile P is stored as P' = Encrypt(K,P) in filename Hash(P')
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L is the list of Hash(P').
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Store Manifest as EncSign(B || L || R) in filename R
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Store each packfile P as P' = Encrypt(Ki, P) in filename Hi
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where Hi = Hash(P') and Ki is a random string
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To read the repository
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decrypt+verify Manifest using private key -> (K, B, L, R)
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decrypt+verify Manifest using private key -> (B, L, R)
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verify R matches Hash(Requested Repository ID)
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for each entry in L:
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get the entry from the server -> P'
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verify Hash(P') matches the entry in L
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decrypt P' using K -> P -> open P with git
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for Hi, Ki in L:
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download file Hi from the server -> P'
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verify Hash(P') matches Hi
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decrypt P' using Ki -> P then open P with git
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Only packs mentioned in L are downloaded.
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+ The manifest looks like this::
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$ gpg -d < 9f42017de5cb482e509ff147d54ceeb0413d6379717f3f0db770f00a
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T+pCUr/1FxbBC93ABIiIgG36EgqaxvgdNYjdmRSueGkgGETc4Qs7di+/yIsq2R5GysiqFaR0 \
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bGSWf9omsoAH84hmED/kR/ZQiOGT/vg2Pg7CGI0xzdlW9GQjeFBAo4vsDDDBxrn5L7F9E532 \
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LOnnPLSIZD7BpmyY/oZiXoP5Vlw=
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b4a4a39365d19282810c19d0f3f24d04dd2d179f refs/tags/something
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$ gpg -d < 5a191cea8c1021a95d813c4007c14f2cc987a40880c2f669430f1916
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b4a4a39365d19282810c19d0f3f24d04dd2d179f refs/tags/version1
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1d323ddadf4cf1d80fced447e637ab3766b168b7 refs/heads/master
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pack :SHA224:00ef27cc2c5b76365e1a46479ed7429e16572c543cdff0a8bf745c7c
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pack :SHA224:b934d8d6c0f48e71b9d7a4d5ea56f024a9bed4f6f2c6f8e688695bee
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repo 9f42017de5cb482e509ff147d54ceeb0413d6379717f3f0db770f00a
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pack :SHA224:cfdf36515e0d0820554fe5fd9f00a4bee17bcf88ec8a752d851c46ee Rc+j8\
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Nv6GOW3mBhWOx6W6jjz3BTX7B6XIJ6RYI+P4TEyy+X6p2PB/fsBL9la0Tuc
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pack :SHA224:a43ccd208d3bd2ea582dbd5407cb8ed6e18b150b1da25c806115eaa5 UXR3/\
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R7awFCUJWYdzXzrlkk7E2Acxq/Y4EfEcd62AwGGe0o0QxL+s5CwWI/NvMhb
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repo :SHA224:5a191cea8c1021a95d813c4007c14f2cc987a40880c2f669430f1916 1
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Pieces yet to be Implemented
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@ -15,7 +15,10 @@ export GITCEPTION="$GITCEPTION+" # Reuse $Gref except when stacked
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Gref="refs/gcrypt/gitception$GITCEPTION"
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Gref_rbranch="refs/heads/master"
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Repoid=
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Packpfx="pack :SHA224:"
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Hashpfx=":SHA224:"
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UrlTag="G."
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Packpfx="pack $Hashpfx"
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Packkey_len=48 # bytes of pack key
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# compat/utility functions
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xecho()
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@ -53,6 +56,7 @@ splitcolon()
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prefix_=${1%%:*}
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suffix_=${1#*:}
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}
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repoidstr() { xecho "repo $Hashpfx$Repoid 1"; }
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## gitception part
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# Fetch giturl $1, file $2
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@ -182,18 +186,16 @@ CLEAN_FINAL()
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ENCRYPT()
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{
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gpg --batch --force-mdc --compress-algo none \
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--passphrase-fd 3 -c 3<<EOF
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$Masterkey
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gpg --batch --force-mdc --compress-algo none --passphrase-fd 3 -c 3<<EOF
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$1
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EOF
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}
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DECRYPT()
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{
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gpg -q --batch --no-default-keyring --secret-keyring /dev/null \
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--keyring /dev/null \
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--passphrase-fd 3 -d 3<<EOF
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$Masterkey
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--keyring /dev/null --passphrase-fd 3 -d 3<<EOF
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$1
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EOF
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}
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@ -260,7 +262,6 @@ make_new_repo()
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local urlid_= fix_config=
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echo_info "Setting up new repository at $URL"
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PUTREPO "$URL"
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Masterkey="$(genkey 128)"
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# We need a relatively short ID for URL+REPO
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# The manifest will be stored at SHA224(urlid_)
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@ -269,12 +270,12 @@ make_new_repo()
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urlid_=$(genkey 9 | tr '/+' 'Zz')
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Repoid=$(xecho_n "$urlid_" | pack_hash)
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echo_info "Repository ID is" "$urlid_"
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isnoteq "${NAME#gcrypt::}" "$URL" && {
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git config "remote.$NAME.url" "gcrypt::$URL/G/$urlid_"
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iseq "${NAME#gcrypt::}" "$URL" || {
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git config "remote.$NAME.url" "gcrypt::$URL/$UrlTag$urlid_"
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fix_config=1
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} || :
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echo_info "Repository URL is" "gcrypt::$URL/G/$urlid_"
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isnonnull "$fix_config" && echo_info "(configuration for $NAME updated)"||:
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}
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echo_info "Repository URL is" "gcrypt::$URL/$UrlTag$urlid_"
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isnull "$fix_config" || echo_info "(configuration for $NAME updated)"
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}
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@ -295,10 +296,10 @@ ensure_connected()
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read_config
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# split out Repoid from URL
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url_id=${URL##*/G/}
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iseq "$url_id" "$URL" && url_id= && return 0 || :
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url_id=${URL##*/"$UrlTag"}
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isnoteq "$url_id" "$URL" || return 0
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URL=${URL%/G/"$url_id"}
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URL=${URL%/"$UrlTag$url_id"}
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Repoid=$(xecho_n "$url_id" | pack_hash)
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TmpManifest_Enc="$Localdir/manifest.$$"
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@ -321,12 +322,10 @@ ensure_connected()
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rm -f "$TmpManifest_Enc"
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trap - EXIT
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Masterkey=$(xecho "$manifest_" | head -n 1)
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Branchlist=$(xecho "$manifest_" | xgrep -E '^[0-9a-f]{40} ')
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Packlist=$(xecho "$manifest_" | xgrep "^$Packpfx")
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rcv_repoid=$(xecho "$manifest_" | xgrep "^repo ")
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iseq "repo $Repoid" "$rcv_repoid" ||
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echo_die "Repository id mismatch!"
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iseq "$(repoidstr)" "$rcv_repoid" || echo_die "Repository id mismatch!"
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}
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do_capabilities()
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@ -343,7 +342,7 @@ do_list()
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xecho "$Branchlist" | while read line_
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do
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isnull "$line_" && break || :
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isnonnull "$line_" || break
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obj_id=${line_%% *}
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ref_name=${line_##* }
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echo_git "$obj_id" "$ref_name"
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@ -363,7 +362,7 @@ do_fetch()
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# The PACK id is the hash of the encrypted git packfile.
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# We only download packs mentioned in the encrypted manifest,
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# and check their digest when received.
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local pack_= rcv_id= packline_= pneed_= pboth_= phave_=
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local pack_= rcv_id= packline_= pneed_= pboth_= phave_= premote_= key_=
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ensure_connected
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@ -376,15 +375,16 @@ do_fetch()
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TmpPack_Encrypted="$Localdir/tmp_pack_ENCRYPTED_.$$"
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trap 'rm -f "$TmpPack_Encrypted"' EXIT
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premote_=$(xecho "$Packlist" | cut -f 1-2 -d ' ')
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# Needed packs is Packlist - (phave & Packlist)
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# The `+` for $GITCEPTION is pointless but we will be safe for stacking
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phave_="$(cat "$Localdir/have_packs+" 2>/dev/null || :)"
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pboth_="$( (xecho "$Packlist"; xecho "$phave_") | sort_C | uniq -d)"
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pneed_="$( (xecho "$Packlist"; xecho "$pboth_") | sort_C | uniq -u)"
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pboth_="$( (xecho "$premote_"; xecho "$phave_") | sort_C | uniq -d)"
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pneed_="$( (xecho "$premote_"; xecho "$pboth_") | sort_C | uniq -u)"
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xecho "$pneed_" | while read packline_
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do
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isnull "$packline_" && continue || :
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isnonnull "$packline_" || continue
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pack_=${packline_#"$Packpfx"}
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rcv_id="$(GET "$URL" "$pack_" | \
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tee "$TmpPack_Encrypted" | pack_hash)"
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@ -392,7 +392,8 @@ do_fetch()
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then
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echo_die "Packfile $pack_ does not match digest!"
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fi
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DECRYPT < "$TmpPack_Encrypted" |
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key_=$(xecho "$Packlist" | grep "$pack_" | cut -f 3 -d ' ')
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DECRYPT "$key_" < "$TmpPack_Encrypted" |
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git index-pack -v --stdin >/dev/null
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# add to local pack list
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xecho "$Packpfx$pack_" >> "$Localdir/have_packs$GITCEPTION"
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@ -410,7 +411,7 @@ do_push()
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# Each git packfile is encrypted and then named for the encrypted
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# file's hash. The manifest is updated with the pack id.
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# The manifest is encrypted.
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local remote_has= remote_want= prefix_= suffix_= line_= pack_id=
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local remote_has= remote_want= prefix_= suffix_= line_= pack_id= key_=
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ensure_connected
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check_recipients
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@ -447,16 +448,17 @@ EOF
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TmpPack_Encrypted="$Localdir/tmp_pack_ENCRYPTED_.$$"
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TmpObjlist="$Localdir/tmp_packrevlist.$$"
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key_=$(genkey "$Packkey_len")
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append "$remote_has" "$remote_want" |
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git rev-list --objects --stdin -- |
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tee "$TmpObjlist" |
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git pack-objects --stdout | ENCRYPT > "$TmpPack_Encrypted"
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git pack-objects --stdout | ENCRYPT "$key_">"$TmpPack_Encrypted"
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# Only send pack if we have any objects to send
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if [ -s "$TmpObjlist" ]
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then
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pack_id=$(pack_hash < "$TmpPack_Encrypted")
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Packlist=$(append "$Packlist" "$Packpfx$pack_id")
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Packlist=$(append "$Packlist" "$Packpfx$pack_id $key_")
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PUT "$URL" "$pack_id" < "$TmpPack_Encrypted"
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fi
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@ -466,15 +468,12 @@ EOF
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# Update manifest
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echo_info "Encrypting manifest to \"$Recipients\""
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echo_info "Requesting manifest key signature"
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echo_info "Requesting manifest signature"
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TmpManifest_Enc="$Localdir/manifest.$$"
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trap 'rm -f "$TmpManifest_Enc"' EXIT
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(xecho "$Masterkey"
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xecho "$Branchlist"
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xecho "$Packlist"
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xecho "repo $Repoid") |
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(xecho "$Branchlist"; xecho "$Packlist"; repoidstr) |
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PRIVENCRYPT "$Recipients" > "$TmpManifest_Enc"
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PUT "$URL" "$Repoid" < "$TmpManifest_Enc"
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