Password cracking - Revision history

Paul at 13:50, 26 August 2018

2018-08-26T13:50:10Z

← Older revision		Revision as of 13:50, 26 August 2018
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	* [https://docs.python.org/3/library/hashlib.html hashlib] is the Python wrapper around OpenSSL and appears to be in the standard library.		* [https://docs.python.org/3/library/hashlib.html hashlib] is the Python wrapper around OpenSSL and appears to be in the standard library.
	* [http://lmdb.readthedocs.io/en/release/ Python bindings to LMDB]		* [http://lmdb.readthedocs.io/en/release/ Python bindings to LMDB]

			[[Category:Python]]

2018-08-26T12:19:35Z

Lookup tables

← Older revision		Revision as of 12:19, 26 August 2018
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	* Can lookup tables be built entirely in memory and then flushed to disk? Regular flushing as used by SQLite prevents data loss but may take longer due to regular I/O. (answer: Yes, just put the whole thing in a huge transaction and commit at the end).		* Can lookup tables be built entirely in memory and then flushed to disk? Regular flushing as used by SQLite prevents data loss but may take longer due to regular I/O. (answer: Yes, just put the whole thing in a huge transaction and commit at the end).
	* Trade-off between size of table (and time to generate) and coverage. May not be worthwhile building lookup tables for anything more than dictionary words and common passwords.		* Trade-off between size of table (and time to generate) and coverage. May not be worthwhile building lookup tables for anything more than dictionary words and common passwords.
			* For very fast hashing such as MD5, it may be quicker to just brute-force everything.

	Possible contents of lookup tables:		Possible contents of lookup tables:

2018-07-24T16:02:41Z

← Older revision		Revision as of 16:02, 24 July 2018
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	* Simple combinations, such as dictionary word concatenated with '1', '123' etc.		* Simple combinations, such as dictionary word concatenated with '1', '123' etc.
	* Every possible combination of case and 0-9a-z from 6-12 characters in length.		* Every possible combination of case and 0-9a-z from 6-12 characters in length.

			== Performance ==

			Vectorisation vs concurrency vs parallelisation.

	== Languages ==		== Languages ==

	Language choice is a combination of ~~speed and~~ available libraries. Obvious initial candidates are:		Language choice is a combination of performance, available libraries and existing knowledge. Obvious initial candidates are:

	* C		* C

2018-07-24T15:58:47Z

Initial steps

← Older revision		Revision as of 15:58, 24 July 2018
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	# If no salt is used (e.g. plain MD5), consult a pre-computed lookup table.		# If no salt is used (e.g. plain MD5), consult a pre-computed lookup table.
			# If small salt is used (less than say 4 bits), consult a pre-computed lookup table.
			# If a sensible algorithm is used (e.g. bcrypt with large salt), check dictionary, then common words, then variants of the previous two, then brute force.

	== Identifying an algorithm ==		== Identifying an algorithm ==

2018-07-24T15:53:12Z

Lookup tables

← Older revision		Revision as of 15:53, 24 July 2018
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	* Trade-off between size of table (and time to generate) and coverage. May not be worthwhile building lookup tables for anything more than dictionary words and common passwords.		* Trade-off between size of table (and time to generate) and coverage. May not be worthwhile building lookup tables for anything more than dictionary words and common passwords.

	~~Contents~~ of lookup tables:		Possible contents of lookup tables:

	* Dictionary words		* Dictionary words

2018-07-24T15:53:01Z

Lookup tables

← Older revision		Revision as of 15:53, 24 July 2018
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	* Which options are the most efficient?		* Which options are the most efficient?
	* Can lookup tables be built entirely in memory and then flushed to disk? Regular flushing as used by SQLite prevents data loss but may take longer due to regular I/O. (answer: Yes, just put the whole thing in a huge transaction and commit at the end).		* Can lookup tables be built entirely in memory and then flushed to disk? Regular flushing as used by SQLite prevents data loss but may take longer due to regular I/O. (answer: Yes, just put the whole thing in a huge transaction and commit at the end).
			* Trade-off between size of table (and time to generate) and coverage. May not be worthwhile building lookup tables for anything more than dictionary words and common passwords.

	Contents of lookup tables:		Contents of lookup tables:

2018-07-24T15:52:07Z

← Older revision		Revision as of 15:52, 24 July 2018
Line 29:		Line 29:
	* Simple combinations, such as dictionary word concatenated with '1', '123' etc.		* Simple combinations, such as dictionary word concatenated with '1', '123' etc.
	* Every possible combination of case and 0-9a-z from 6-12 characters in length.		* Every possible combination of case and 0-9a-z from 6-12 characters in length.

			== Languages ==

			Language choice is a combination of speed and available libraries. Obvious initial candidates are:

			* C
			* CPython (reference implementation of Python)
			* PyPy (Python written in Python - supposedly faster than CPython but sometimes behind in terms of version support)

	== Libraries ==		== Libraries ==

2018-07-24T15:50:43Z

Libraries

← Older revision		Revision as of 15:50, 24 July 2018
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	== Libraries ==		== Libraries ==

	Ultimately most libraries end up being a wrapper around [[OpenSSL]].		Ultimately most crypto libraries end up being a wrapper around [[OpenSSL]].

	=== Python ===		=== Python ===

2018-07-24T15:50:35Z

← Older revision		Revision as of 15:50, 24 July 2018
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	* Simple combinations, such as dictionary word concatenated with '1', '123' etc.		* Simple combinations, such as dictionary word concatenated with '1', '123' etc.
	* Every possible combination of case and 0-9a-z from 6-12 characters in length.		* Every possible combination of case and 0-9a-z from 6-12 characters in length.

	~~=== Lightning Memory-Mapped Database (LMDB) ===~~

	* [http://lmdb.readthedocs.io/en/release/ Python bindings to LMDB]

	== Libraries ==		== Libraries ==
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	=== Python ===		=== Python ===

	[https://docs.python.org/3/library/hashlib.html hashlib] is the Python wrapper around OpenSSL and appears to be in the standard library.		* [https://docs.python.org/3/library/hashlib.html hashlib] is the Python wrapper around OpenSSL and appears to be in the standard library.
			* [http://lmdb.readthedocs.io/en/release/ Python bindings to LMDB]

2018-07-24T15:21:06Z

Lookup tables

← Older revision		Revision as of 15:21, 24 July 2018
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	* What options does the chosen language support?		* What options does the chosen language support?
	* Which options are the most efficient?		* Which options are the most efficient?
	* Can lookup tables be built entirely in memory and then flushed to disk? Regular flushing as used by SQLite prevents data loss but may take longer due to regular I/O.		* Can lookup tables be built entirely in memory and then flushed to disk? Regular flushing as used by SQLite prevents data loss but may take longer due to regular I/O. (answer: Yes, just put the whole thing in a huge transaction and commit at the end).

	Contents of lookup tables:		Contents of lookup tables: