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#!/usr/bin/env python3
import os
import sys
import base64
import struct
"""
byte[] AUTH_MAGIC = "openssh-key-v1\x00"
string ciphername
string kdfname
string kdfoptions
int number of keys N
string publickey1
string publickey2
...
string publickeyN
string encrypted, padded list of private keys
"""
class Parser:
"""
"""
def __init__(self, data = b""):
"""
"""
self.data = data
def parse_magic(self):
"""
"""
if len(self.data) < 15 or not self.data.startswith(b"openssh-key-v1\x00"):
raise Exception("unable to parse OpenSSH key: magic 'openssh-key-v1' not found")
self.data = self.data[15:]
def parse_num(self, text):
"""
"""
if (4 > len(self.data)):
raise Exception(f"unable to parse OpenSSH key: bad ssh-num {text}")
num = struct.unpack('>I', self.data[:4])[0]
self.data = self.data[4:]
return num
def parse_string(self, text):
"""
"""
num = self.parse_num(text)
if (num > len(self.data)):
raise Exception(f"unable to parse OpenSSH key: bad ssh-string {text}")
ret = self.data[:num]
self.data = self.data[num:]
return ret
def usage(f = ""):
"""
"""
if len(f) != 0:
print("tinyssh-convert: fatal: %s" % (f))
print("tinyssh-convert: usage: tinyssh-convert out-tinysshkeydir < in-opensshfile")
print()
exit(100)
def writesync(fn = "", data = b""):
"""
"""
f = open(fn, 'wb')
f.write(data)
f.flush()
os.fsync(f.fileno())
f.close()
if __name__ == "__main__":
if len(sys.argv) != 2:
usage("")
d=sys.argv[1]
if os.path.exists(d):
usage("out-tinysshkeydir exist")
lines = sys.stdin.readlines()
data = ""
flagbegin = 0
for line in lines:
if line.startswith("-----BEGIN OPENSSH PRIVATE KEY-----"):
flagbegin = 1
continue
if line.startswith("-----END OPENSSH PRIVATE KEY-----"):
break
if flagbegin:
data += line
if flagbegin == 0:
raise Exception("unable to parse OpenSSH key: no line -----BEGIN OPENSSH PRIVATE KEY----- found")
data = base64.b64decode(data)
# parse key
p = Parser(data)
p.parse_magic()
ciphername = p.parse_string("ciphername")
if ciphername != b'none':
raise Exception("unable to parse OpenSSH key: can't convert encrypted key: ciphername != none")
kdfname = p.parse_string("kdfname")
if kdfname != b'none':
raise Exception("unable to parse OpenSSH key: can't convert encrypted key: kdfname != none")
kdfoptions = p.parse_string("kdfoptions")
if kdfoptions != b'':
raise Exception("unable to parse OpenSSH key: can't convert encrypted key: kdfoptions != ''")
pklen = p.parse_num("publickeys")
if (pklen != 1):
raise Exception("unable to parse OpenSSH key: more than one key in the file")
pkssh = p.parse_string("publickey")
skssh = p.parse_string("secretkeys")
# parse secret key
p = Parser(skssh)
p.parse_num("checkint")
p.parse_num("checkint")
sk = []
t = p.parse_string("secret-key type")
if t != b'ssh-ed25519':
raise Exception(f"unable to parse OpenSSH key: secret-key type={t}: not ssh-ed25519 key")
pk = p.parse_string("public-key")
pklen = len(pk)
sk = p.parse_string("secret-key")
sklen = len(sk)
p.parse_string("comment")
if pklen != 32:
raise Exception(f"unable to parse OpenSSH key: public-key length={pklen}: not 32")
if sklen != 64:
raise Exception(f"unable to parse OpenSSH key: secret-key length={sklen}: not 64")
os.umask(0o0022)
os.mkdir(d)
os.chdir(d)
writesync("ed25519.pk", pk)
os.umask(0o0077)
writesync(".ed25519.sk", sk)
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