#!/usr/bin/python

sig="""
-----BEGIN PGP SIGNED MESSAGE-----

"""

#
# 2003/8/23
#
# Read key from SSH-keyfile and store in a file.
# Secret keys must have an empty passphrase in order to extract
# the secret decryption value.
#
# SECRETKEY-Structure assumed:
#
# octets    value meaning
# 1-32            Formatstring "SSH PRIVATE KEY FILE FORMAT 1.1"
# 33-40           Nullstring 8 octetts
# 41/42           Length of Modulus
# 43+x            MPI: modulus n
# 43+x+y          MPI: encryption e
# 43+x+y+2  0     Nullstring 2 octetts
# 43+x+y+4        Length of User-ID
# + L octetts     User-ID
# + 4 octetts     unknown data
#                 if secet key is unencrypted:
#                     MPI: Decryption (secret key)
#                     MPI: u  multiplicative inverse of p mod q
#                     MPI: p
#                     MPI: q (q<p)
#                     4 octets  Nullstring
#                 else:
#                     block of 3DES-encrypted data
#                 End


import sys, pure

i = 0

#########################################################
def readNbytes(N):
    global i
    Length = 0L
    while N > 0 and i < len(keyfile) :
          Length = Length * 256 + ord(keyfile[int(i)])
          i = i + 1
          N = N - 1
    return Length

#########################################################
def readMPI():
    global i
    Length = 0
    Length = readNbytes(2)   # in bits
    Bytes = Length / 8
    if Length % 8 != 0 :
         Bytes  = Bytes + 1
    # read L octets
    print "Reading " , pure.toString(Length), " bit or ", pure.toString(Bytes), " bytes"

    X = 1
    MPI = 0L
    while X <= Bytes and i < len(keyfile) :
         MPI = MPI * 256 + ord(keyfile[int(i)])
         i = i + 1
         X = X + 1
    return MPI

#########################################################

if len(sys.argv) != 3 :
       print "usage: read-sshkey infile outfile"
else:
       try:
            FILE = open (sys.argv[1], "r")
            keyfile = FILE.read()
            FILE.close()
            print "Reading " + pure.toString(len(keyfile)) +  " bytes."
       except:
            print "Cannot read input file"
            sys.exit(3)

       # read first line
       Formatstring = ""
       while ord(keyfile[i]) != 10 :
            Formatstring = Formatstring + keyfile[i]
            i = i + 1

       if Formatstring[:15] == "SSH PRIVATE KEY" :
            print Formatstring
            begin = readNbytes(10)
            i =  i + 1
            Modulus = 0L
            Encryption = 0L
            Modulus = readMPI()
            print "Modulus = ", pure.toString(Modulus)
            print
            Encryption = readMPI()
            print "Encryption = ", pure.toString(Encryption)
            print
            neu = readNbytes(2)
            Length = readNbytes(2)
            UserID = keyfile[i:int(i+Length)]
            print UserID
            print
            i = i + Length + 4
            Decryption = 0L
            P = Q = U = 0L

            Length = 0
            Length = ord(keyfile[int(i)]) * 256 + ord(keyfile[int(i+1)])
            print "Looking for unencrypted PRIVATE KEY of length ",
            print pure.toString(Length)
            if Length/8 < len(keyfile) - i :
                 Decryption = readMPI()
                 print "Decryption = ", pure.toString(Decryption)
                 print
                 U = readMPI()
                 print "u = ", pure.toString(U)
                 P = readMPI()
                 print "p = ", pure.toString(P)
                 Q = readMPI()
                 print "q = ", pure.toString(Q)
            else :
                 print "Secret key is 3-DES encrypted."

            KEY = ""
            KEY = KEY + "Modulus = " + pure.toString(Modulus) + "\n"
            KEY = KEY + "Encryption = " + pure.toString(Encryption) + "\n"
            KEY = KEY + "Decryption = " + pure.toString(Decryption) + "\n"
            KEY = KEY + "Hashmodulus = 1" + "\n"
            KEY = KEY + "Generator = 1" + "\n"
            KEY = KEY +  UserID + "\n"
            KEY = KEY + "Protection = None" + "\n"
            KEY = KEY + "Securityhash = None" + "\n"

#------------------------------------------------------------------#

       else:
            print "PUBLIC KEY"
            Modulus = 0L
            M = ""
            Encryption = 0L
            E = ""
            UserID = ""

            i = 0
            while ord(keyfile[i]) != 32:
                i = i + 1
            i = i + 1
            while ord(keyfile[i]) != 32:
                E = E + keyfile[i]
                i = i + 1
            Encryption = pure.toString(E)
            i = i + 1
            while ord(keyfile[i]) != 32:
                M = M + keyfile[i]
                i = i + 1
            i = i + 1
            Modulus = pure.toString(M)
            UserID = pure.Line(keyfile[i:])

            KEY = ""
            KEY = KEY + "Modulus = " + pure.toString(Modulus) + "\n"
            KEY = KEY + "Encryption = " + pure.toString(Encryption) + "\n"
            KEY = KEY + "Hashmodulus = 1" + "\n"
            KEY = KEY + "Generator = 1" + "\n"
            KEY = KEY + UserID + "\n"
            KEY = KEY + "Securityhash = None" + "\n"
            print KEY

#------------------------------------------------------------------#

       outfile = sys.argv[2]

       try:
            FILE = open (outfile, "w")
            FILE.write(KEY)
            FILE.close()
       except:
            print "Cannot write file to filesystem"
            sys.exit(3)

print "EXIT"
sys.exit(0)

##################################################################

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"""