Cryptanalysis

Break encryption algorithms

These tests will allow you to hone your cryptography skills. You will be faced with an encoded data. The challenge is to find the type of encoding or encryption and revert it back to find the solution.

Prerequisites:

– Knowledge of most common encoding formats.
– Knowledge of most common hash algorithms and ciphers.
– Knowledge of a scripting language.

75 Challenges

Results	Name	Validations	Number of points	Difficulty	Author	Note	Solution	Date
	Encoding - ASCII	25% 100296	5		Xartrick		10	4 December 2012
	Encoding - UU	20% 76679	5		g0uZ		10	7 October 2006
	Hash - DCC	3% 10903	5		Podalirius		1	13 July 2021
	Hash - DCC2	3% 9901	5		Podalirius		1	13 July 2021
	Hash - LM	3% 10296	5		Podalirius		2	13 July 2021
	Hash - Message Digest 5	17% 65594	5		g0uZ		7	31 January 2010
	Hash - NT	3% 8450	5		Podalirius		2	13 July 2021
	Hash - SHA-2	9% 34827	5		koma		4	3 June 2012
	Shift cipher	6% 22888	10		m31z0nyx		10	16 February 2011
	CISCO - Salted Password	2% 6860	10		Tidusrose		3	13 July 2021
	Pixel Madness	5% 17585	15		Ryscrow		10	3 February 2011
	ELF64 - PID encryption	3% 8776	15		Lu33Y		10	8 February 2012
	File - PKZIP	4% 14572	15		g0uZ		6	30 August 2010
	Monoalphabetic substitution - Caesar	5% 18699	15		Arod		5	22 October 2011
	Circular Bit Shift	1% 2508	20		BlackRaven		3	21 March 2023
	Known plaintext - XOR	3% 10354	20		Ryscrow		5	3 February 2011
	Code - Pseudo Random Number Generator	2% 4261	20		Tosh		6	19 December 2012
	Encoding - Codebook	1% 764	20		n3rada		1	21 March 2023
	File - PKZIP 2	1% 735	20		kevin.mille		2	8 November 2024
	File - Insecure storage 1	3% 9995	20		g0uZ		7	6 February 2012
	Polyalphabetic substitution - Vigenère	3% 11381	20		Arod		3	26 October 2011
	System - Android lock pattern	2% 7521	20		Silentd		5	23 December 2012
	Transposition - Rail Fence	2% 7139	20		YellowS4		4	6 April 2014
	AES - CBC - Bit-Flipping Attack	1% 1863	25		Tie21		5	17 June 2018
	AES - ECB	1% 3082	25		cez40		4	29 November 2015
	AES - ECB - Copy Paste	1% 558	25		Vozec		1	5 February 2024
	DSA - Implementation error	1% 289	25		Vozec		1	13 December 2024
	LFSR - Known plaintext	1% 1354	25		Brissouille		2	28 November 2017
	RSA - Factorisation	2% 5682	25		HacKSpider		5	12 September 2010
	RSA - Decipher Oracle	1% 2345	25		Zweisamkeit		4	11 May 2017
	Service - Timing attack	1% 3125	25		g0uZ , koma		5	28 October 2012
	Monoalphabetic substitution - Polybe	2% 4282	25		koma		6	6 December 2011
	Twisted secret	1% 700	25		NonStandardModel		2	14 August 2020
	Initialisation Vector	1% 2543	25		manticore , notfound404		6	25 August 2015
	Hill Cipher	1% 452	30		LetMeR00t		1	21 March 2023
	GEDEFU	1% 673	30		makhno		1	13 September 2016
	OTP - Implementation error	1% 656	30		Podalirius		3	22 March 2021
	RSA - Corrupted key 1	1% 597	30		blackndoor		2	28 November 2017
	RSA - Continued fractions	1% 1744	30		sambecks		1	8 September 2015
	RSA - Common modulus	1% 2335	30		franb		3	24 December 2016
	Service - Hash length extension attack	1% 1323	30		koma		1	19 August 2015
	Shamir Secret Sharing - Introduction	1% 548	30		Vozec		2	5 February 2024
	AES - 4 Rounds	1% 479	35		Cryptanalyse		0	5 September 2018
	ECDSA - Introduction	1% 466	35		Jrmbt		2	22 September 2019
	ElGamal - Fault attack (Introduction)	1% 153	35		Vozec		0	13 December 2024
	RSA - Padding	1% 391	35		Tosh		0	9 October 2016
	RSA - Signature	1% 316	35		sar		1	9 March 2020
	Shamir Secret Sharing - Traitor	1% 204	35		Vozec		1	5 February 2024
	AES128 - CTR	1% 895	40		Tosh		2	28 August 2015
	PHP - mt_rand	1% 250	40		NonStandardModel		0	28 March 2022
	Discrete logarithm problem	1% 1518	40		RFC4949		3	8 June 2014
	RSA - Corrupted key 2	1% 418	40		blackndoor		1	11 January 2018
	RSA - Corrupted key 3	1% 284	40		blackndoor		0	5 September 2019
	RSA - Multiple recipients	1% 1856	40		franb		4	29 November 2015
	AES - Fault attack #1	1% 292	50		Cryptanalyse		1	20 September 2018
	FEAL - Differential Cryptanalysis	1% 100	50		Tosh		1	28 March 2022
	Goldreich Goldwasser Halevi \| Weak Parameter	1% 112	50		Vozec		0	13 December 2024
	Enigma Machine	1% 347	50		peyman		2	12 October 2016
	Side Channel - AES : CPA	1% 191	50		cb34		0	28 March 2022
	ECDHE	1% 348	60		Tosh		2	20 November 2016
	NTRU \| Multiple Transmission	1% 102	60		Vozec		0	13 December 2024
	NTRU \| Weak Parameter	1% 95	60		Vozec		0	13 December 2024
	RSA - H-rabin	1% 174	60		Vozec		0	21 March 2023
	RSA - Lee cooper	1% 247	60		blackndoor , Synacktiv		1	7 November 2019
	Service - CBC Padding	1% 1522	60		koma		2	4 October 2012
	Side Channel - AES : first round	1% 206	60		walafc0		0	28 March 2022
	Polyalphabetic substitution - One Time Pad	1% 488	60		Thanat0s		0	2 June 2013
	White-Box Cryptography	1% 375	60		Cryptanalyse		3	21 October 2018
	AES - Weaker variant	1% 249	70		Cryptanalyse		1	29 August 2018
	Shamir Secret Sharing - Reduction	1% 168	70		Vozec		0	5 February 2024
	Hash - SHA-3	1% 312	75		Revenger		1	10 December 2016
	AES - Fault attack #2	1% 211	80		Cryptanalyse		1	20 September 2018
	Shamir Secret Sharing - Irreducible ?	1% 127	90		Mr7F		1	5 February 2024
	AES-PMAC	1% 108	100		Cryptanalyse		0	26 May 2019
	ECDSA - Implementation error	1% 145	100		Tosh		0	29 September 2019

Challenge Results

Pseudo	Challenge	Lang	Date
Lucas	Chiffrement par décalage		8 October 2026 at 20:40
Анжелика Акимкина	Chiffrement par décalage		8 October 2026 at 20:15
unknow.75	AES-PMAC		8 October 2026 at 20:08
Анжелика Акимкина	Encoding - UU		8 October 2026 at 20:08
Howitzer	PHP - mt_rand		8 October 2026 at 20:00
LL_soccer	Shamir Secret Sharing - Reduction		8 October 2026 at 19:58
ᖒᕾᕲᙉᕩᔾ	White-Box Cryptography		8 October 2026 at 19:45
Анжелика Акимкина	Encoding - ASCII		8 October 2026 at 19:44
Anant Raj	Hash - NT		8 October 2026 at 19:41
InSanity	Shamir Secret Sharing - Introduction		8 October 2026 at 19:21