"""fontTools.misc.eexec.py -- Module implementing the eexec and
charstring encryption algorithm as used by PostScript Type 1 fonts.
"""
# Warning: Although a Python implementation is provided here,
# all four public functions get overridden by the *much* faster
# C extension module eexecOp, if available.
import string
error = "eexec.error"
def _decryptChar(cipher, R):
cipher = ord(cipher)
plain = ( (cipher ^ (R>>8)) ) & 0xFF
R = ( (cipher + R) * 52845L + 22719L ) & 0xFFFF
return chr(plain), R
def _encryptChar(plain, R):
plain = ord(plain)
cipher = ( (plain ^ (R>>8)) ) & 0xFF
R = ( (cipher + R) * 52845L + 22719L ) & 0xFFFF
return chr(cipher), R
def decrypt(cipherstring, R):
# I could probably speed this up by inlining _decryptChar,
# but... we've got eexecOp, so who cares ;-)
plainList = []
for cipher in cipherstring:
plain, R = _decryptChar(cipher, R)
plainList.append(plain)
plainstring = string.join(plainList, '')
return plainstring, int(R)
def encrypt(plainstring, R):
cipherList = []
for plain in plainstring:
cipher, R = _encryptChar(plain, R)
cipherList.append(cipher)
cipherstring = string.join(cipherList, '')
return cipherstring, int(R)
def hexString(s):
import binascii
return binascii.hexlify(s)
def deHexString(h):
import binascii
h = "".join(h.split())
return binascii.unhexlify(h)
def _test():
import fontTools.misc.eexecOp as eexecOp
testStr = "\0\0asdadads asds\265"
print decrypt, decrypt(testStr, 12321)
print eexecOp.decrypt, eexecOp.decrypt(testStr, 12321)
print encrypt, encrypt(testStr, 12321)
print eexecOp.encrypt, eexecOp.encrypt(testStr, 12321)
if __name__ == "__main__":
_test()
try:
from fontTools.misc.eexecOp import *
except ImportError:
pass # Use the slow Python versions
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