Initial commitHEADmaster

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

3 files changed, 144 insertions, 0 deletions

diff --git a/COPYING b/COPYING
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+Copyright (C) 2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
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+## chacha20.sh
+#### by zx2c4
+
+You probably shouldn't use this for anything.
+
+### Usage
+
+```
+chacha20 [HEX KEY] [NUMERIC NONCE] [HEX CIPHERTEXT]
+```
+
+### Example
+
+```
+local ciphertext="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"
+local key="a92075897e378548a3fb7be830a7e36ea6c17117c16c9bc2def0a719eccec653"
+local nonce=5394271251748129296
+
+chacha20 "$key" "$nonce" "$ciphertext"
+```
+
+
+
diff --git a/chacha20.sh b/chacha20.sh
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+#!/bin/bash
+# SPDX-License-Identifier: MIT
+# Copyright (C) 2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+
+
+rol() {
+	echo $(( (($1 << $2) | ($1 >> (32 - $2))) & 0xffffffff ))
+}
+
+quarter_round() {
+	local -n x=$1; shift
+	x[$1]=$(( (x[$1] + x[$2]) & 0xffffffff ))
+	x[$4]=$(rol $(( (x[$4] ^ x[$1]) & 0xffffffff )) 16)
+	x[$3]=$(( (x[$3] + x[$4]) & 0xffffffff ))
+	x[$2]=$(rol $(( (x[$2] ^ x[$3]) & 0xffffffff )) 12)
+	x[$1]=$(( (x[$1] + x[$2]) & 0xffffffff ))
+	x[$4]=$(rol $(( (x[$4] ^ x[$1]) & 0xffffffff )) 8)
+	x[$3]=$(( (x[$3] + x[$4]) & 0xffffffff ))
+	x[$2]=$(rol $(( (x[$2] ^ x[$3]) & 0xffffffff )) 7)
+}
+
+c() {
+	echo $(( ($1 << 2) + $2 ))
+}
+
+double_round() {
+	quarter_round $1 $(c 0 0) $(c 1 0) $(c 2 0) $(c 3 0)
+	quarter_round $1 $(c 0 1) $(c 1 1) $(c 2 1) $(c 3 1)
+	quarter_round $1 $(c 0 2) $(c 1 2) $(c 2 2) $(c 3 2)
+	quarter_round $1 $(c 0 3) $(c 1 3) $(c 2 3) $(c 3 3)
+	quarter_round $1 $(c 0 0) $(c 1 1) $(c 2 2) $(c 3 3)
+	quarter_round $1 $(c 0 1) $(c 1 2) $(c 2 3) $(c 3 0)
+	quarter_round $1 $(c 0 2) $(c 1 3) $(c 2 0) $(c 3 1)
+	quarter_round $1 $(c 0 3) $(c 1 0) $(c 2 1) $(c 3 2)
+}
+
+twenty_rounds() {
+	double_round $1
+	double_round $1
+	double_round $1
+	double_round $1
+	double_round $1
+	double_round $1
+	double_round $1
+	double_round $1
+	double_round $1
+	double_round $1
+}
+
+le() {
+	echo $(( ($1 >> 0) & 0xff)) $(( ($1 >> 8) & 0xff)) $(( ($1 >> 16) & 0xff)) $(( ($1 >> 24) & 0xff))
+}
+
+one_block() {
+	local -n state=$1
+	local -n stream=$2
+	local block=( ${state[@]} )
+	twenty_rounds block
+	for (( i=0; i < 16; i++ )); do
+		stream+=( $(le $(( (state[$i] + block[$i]) & 0xffffffff )) ) )
+	done
+	state[12]=$(( (state[12] + 1) & 0xffffffff ))
+	(( state[12] != 0 )) || state[13]=$(( (state[13] + 1) & 0xffffffff ))
+}
+
+dehex() {
+	echo $(( (0x${1:0:2} << 0) | (0x${1:2:2} << 8) | (0x${1:4:2} << 16) | (0x${1:6:2} << 24) ))
+}
+
+# Usage: chacha20 [HEX KEY] [NUMERIC NONCE] [HEX CIPHERTEXT]
+chacha20() {
+	local cstate=(
+		1634760805 857760878 2036477234 1797285236
+		$(dehex ${1:0:8}) $(dehex ${1:8:8}) $(dehex ${1:16:8}) $(dehex ${1:24:8})
+		$(dehex ${1:32:8}) $(dehex ${1:40:8}) $(dehex ${1:48:8}) $(dehex ${1:56:8})
+		0 0 $(( $2 & 0xffffffff )) $(( ($2 >> 32) & 0xffffffff ))
+	)
+	local ciphertext="$3"
+	local n=0
+	while true; do
+		[[ -n ${ciphertext:$n} ]] || { echo; return 0; }
+		local cstream=()
+		one_block cstate cstream
+		for (( i=0; i < 64; i++ )); do
+			[[ -n ${ciphertext:$n} ]] || { echo; return 0; }
+			printf '%02x' $(( cstream[$i] ^ 0x${ciphertext:$n:2} ))
+			(( n+=2 ))
+		done
+	done
+}
+
+test_vector() {
+	local ciphertext="d42efa92e92968b7542cf7a42db750b5c5b29d175e0aca37bf60aed298e9fa596762e6430c7780823361a3ffc1a08f56bcec654388a5ff516430ee34b75c2868c352d2ac782aa610b8b24c804f99b236948f66cba191ed06426dc1ae5593dd939e88347f98ebbe61f9a90fd9c487d5efcc718c0ecead02cfa261dfb1fe3bdcc058b571a183c9b4af9d5412cdea06d64ee5270cc3bba80a8175c3c9d4353e539faa20c068392c96395381da070f44a5470eb3870d1bc1e54135125896698a1aa39d3dd4b18e1f9687dad319e2b13a1974a0009f4dbccb0ce9ec10df2a88dc3051465653986a2614055481550b3c85dd33811129824635e1db597b"
+	local plaintext="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"
+	local key="a92075897e378548a3fb7be830a7e36ea6c17117c16c9bc2def0a719eccec653"
+	local nonce=5394271251748129296
+
+	[[ $(chacha20 "$key" "$nonce" "$ciphertext") == "$plaintext" ]] && echo pass || echo fail
+	[[ $(chacha20 "$key" "$nonce" "$plaintext") == "$ciphertext" ]] && echo pass || echo fail
+}
+
+test_vector