diff options
| -rw-r--r-- | youtube_dl/utils.py | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py index 8bd075eaf..807183f4a 100644 --- a/youtube_dl/utils.py +++ b/youtube_dl/utils.py @@ -3319,6 +3319,57 @@ class PerRequestProxyHandler(compat_urllib_request.ProxyHandler): self, req, proxy, type) +# Both long_to_bytes and bytes_to_long are adapted from PyCrypto, which is +# released into Public Domain +# https://github.com/dlitz/pycrypto/blob/master/lib/Crypto/Util/number.py#L387 + +def long_to_bytes(n, blocksize=0): + """long_to_bytes(n:long, blocksize:int) : string + Convert a long integer to a byte string. + + If optional blocksize is given and greater than zero, pad the front of the + byte string with binary zeros so that the length is a multiple of + blocksize. + """ + # after much testing, this algorithm was deemed to be the fastest + s = b'' + n = int(n) + while n > 0: + s = compat_struct_pack('>I', n & 0xffffffff) + s + n = n >> 32 + # strip off leading zeros + for i in range(len(s)): + if s[i] != b'\000'[0]: + break + else: + # only happens when n == 0 + s = b'\000' + i = 0 + s = s[i:] + # add back some pad bytes. this could be done more efficiently w.r.t. the + # de-padding being done above, but sigh... + if blocksize > 0 and len(s) % blocksize: + s = (blocksize - len(s) % blocksize) * b'\000' + s + return s + + +def bytes_to_long(s): + """bytes_to_long(string) : long + Convert a byte string to a long integer. + + This is (essentially) the inverse of long_to_bytes(). + """ + acc = 0 + length = len(s) + if length % 4: + extra = (4 - length % 4) + s = b'\000' * extra + s + length = length + extra + for i in range(0, length, 4): + acc = (acc << 32) + compat_struct_unpack('>I', s[i:i + 4])[0] + return acc + + def ohdave_rsa_encrypt(data, exponent, modulus): ''' Implement OHDave's RSA algorithm. See http://www.ohdave.com/rsa/ |