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Diffstat (limited to 'docs/wipy')
| -rw-r--r-- | docs/wipy/general.rst | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/docs/wipy/general.rst b/docs/wipy/general.rst index 9b3f54df2..eca9bbe45 100644 --- a/docs/wipy/general.rst +++ b/docs/wipy/general.rst @@ -253,3 +253,23 @@ SSL sockets need to be created the following way before wrapping them with. import ssl s = socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_SEC) ss = ssl.wrap_socket(s) + +Incompatibilities in uhashlib module +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Due to hardware implementation details of the WiPy, data must be buffered before being +digested, which would make it impossible to calculate the hash of big blocks of data that +do not fit in RAM. In this case, since most likely the total size of the data is known +in advance, the size can be passed to the constructor and hence the HASH hardware engine +of the WiPy can be properly initialized without needing buffering. If ``block_size`` is +to be given, an initial chunk of ``data`` must be passed as well. **When using this extension, +care must be taken to make sure that the length of all intermediate chunks (including the +initial one) is a multiple of 4 bytes.** The last chunk may be of any length. + +Example:: + + hash = uhashlib.sha1('abcd1234', 1001) # length of the initial piece is multiple of 4 bytes + hash.update('1234') # also multiple of 4 bytes + ... + hash.update('12345') # last chunk may be of any length + hash.digest() |