https://x3ric.com/blog/tags/hash/CTF notes, systems work, and writeups.Hugoen-usSat, 06 Jun 2026 21:41:13 +0200https://x3ric.com/blog/posts/HackTheBox-secure-source-Challenge/https://x3ric.com/blog/posts/HackTheBox-secure-source-Challenge/Sun, 16 Feb 2025 00:20:00 +0800challengehtbcryptoprnglatticeecchashsecure source: reconstruct the PRNG state from the leak, replay it, and recover the flag.https://x3ric.com/blog/posts/HackTheBox-signup-Challenge/https://x3ric.com/blog/posts/HackTheBox-signup-Challenge/Sun, 16 Feb 2025 00:20:00 +0800challengehtbcryptohashsignup: reduce the hash constraint to a small search, test candidates, and recover the flag.https://x3ric.com/blog/posts/HackTheBox-alphascii-clashing-Challenge/https://x3ric.com/blog/posts/HackTheBox-alphascii-clashing-Challenge/Thu, 13 Feb 2025 00:20:00 +0800challengehtbcryptohashalphascii clashing: reduce the hash constraint to a small search, test candidates, and recover the flag.https://x3ric.com/blog/posts/HackTheBox-Digital-Safety-Annex-Challenge/https://x3ric.com/blog/posts/HackTheBox-Digital-Safety-Annex-Challenge/Tue, 04 Feb 2025 00:20:00 +0800challengehtbcryptoecchashDigital-Safety-Annex: use the curve leak or invalid-curve path to recover the secret and decrypt the flag.https://x3ric.com/blog/posts/HackTheBox-Interception-Challenge/https://x3ric.com/blog/posts/HackTheBox-Interception-Challenge/Fri, 31 Jan 2025 09:20:00 +0800challengehtbcryptolatticehashInterception: model the leak as a small lattice problem, recover the secret, and verify the flag.https://x3ric.com/blog/posts/HackTheBox-Not-that-random-Challenge/https://x3ric.com/blog/posts/HackTheBox-Not-that-random-Challenge/Fri, 31 Jan 2025 09:20:00 +0800challengehtbcryptoprnghashNot that random: reconstruct the PRNG state from the leak, replay it, and recover the flag.https://x3ric.com/blog/posts/HackTheBox-Permuted-Challenge/https://x3ric.com/blog/posts/HackTheBox-Permuted-Challenge/Fri, 31 Jan 2025 09:20:00 +0800challengehtbcryptorsaaeshashPermuted: exploit the RSA structure, recover the missing secret, and decrypt the flag.https://x3ric.com/blog/posts/HackTheBox-Jenny-From-The-Block-Challenge/https://x3ric.com/blog/posts/HackTheBox-Jenny-From-The-Block-Challenge/Thu, 23 Jan 2025 09:20:00 +0800challengehtbcryptohashJenny From The Block: reduce the hash constraint to a small search, test candidates, and recover the flag.https://x3ric.com/blog/posts/HackTheBox-MSS-Challenge/https://x3ric.com/blog/posts/HackTheBox-MSS-Challenge/Thu, 23 Jan 2025 09:20:00 +0800challengehtbcryptorsaaeshashMSS: exploit the RSA structure, recover the missing secret, and decrypt the flag.https://x3ric.com/blog/posts/HackTheBox-AHS512-Challenge/https://x3ric.com/blog/posts/HackTheBox-AHS512-Challenge/Wed, 22 Jan 2025 09:20:00 +0800challengehtbcryptoprnghashAHS512: reconstruct the PRNG state from the leak, replay it, and recover the flag.https://x3ric.com/blog/posts/HackTheBox-Arranged-Challenge/https://x3ric.com/blog/posts/HackTheBox-Arranged-Challenge/Wed, 22 Jan 2025 09:20:00 +0800challengehtbcryptoaeslatticeecchashArranged: abuse the AES misuse, derive the missing key material, and decrypt the flag.https://x3ric.com/blog/posts/HackTheBox-Bank-er-smith-Challenge/https://x3ric.com/blog/posts/HackTheBox-Bank-er-smith-Challenge/Wed, 22 Jan 2025 09:20:00 +0800challengehtbcryptorsahashBank-er-smith: exploit the RSA structure, recover the missing secret, and decrypt the flag.https://x3ric.com/blog/posts/HackTheBox-Bloom-Bloom-Challenge/https://x3ric.com/blog/posts/HackTheBox-Bloom-Bloom-Challenge/Wed, 22 Jan 2025 09:20:00 +0800challengehtbcryptoaeslatticehashBloom Bloom: abuse the AES misuse, derive the missing key material, and decrypt the flag.https://x3ric.com/blog/posts/HackTheBox-Im-gRoot-Challenge/https://x3ric.com/blog/posts/HackTheBox-Im-gRoot-Challenge/Wed, 22 Jan 2025 09:20:00 +0800challengehtbcryptohashI'm gRoot: reduce the hash constraint to a small search, test candidates, and recover the flag.https://x3ric.com/blog/posts/HackTheBox-Android-in-the-Middle-Challenge/https://x3ric.com/blog/posts/HackTheBox-Android-in-the-Middle-Challenge/Tue, 07 Jan 2025 09:20:00 +0800challengehtbcryptoaeshashAndroid-in-the-Middle: abuse the AES misuse, derive the missing key material, and decrypt the flag.https://x3ric.com/blog/posts/HackTheBox-Embryonic-Plant-Challenge/https://x3ric.com/blog/posts/HackTheBox-Embryonic-Plant-Challenge/Fri, 13 Dec 2024 09:20:00 +0800challengehtbcryptoaesprnghashEnter the challenge flag to unlock this writeup.https://x3ric.com/blog/posts/HackTheBox-LostKey-Challenge/https://x3ric.com/blog/posts/HackTheBox-LostKey-Challenge/Fri, 13 Dec 2024 09:20:00 +0800challengehtbcryptorsaaeslatticeecchashEnter the challenge flag to unlock this writeup.https://x3ric.com/blog/posts/HackTheBox-ReMeeting-the-Wheel-Challenge/https://x3ric.com/blog/posts/HackTheBox-ReMeeting-the-Wheel-Challenge/Fri, 13 Dec 2024 09:20:00 +0800challengehtbcryptorsaaeshashEnter the challenge flag to unlock this writeup.https://x3ric.com/blog/posts/HackTheBox-Signing-Factory-Challenge/https://x3ric.com/blog/posts/HackTheBox-Signing-Factory-Challenge/Fri, 13 Dec 2024 09:20:00 +0800challengehtbcryptoprnghashSigning Factory: reconstruct the PRNG state from the leak, replay it, and recover the flag.https://x3ric.com/blog/posts/HackTheBox-Rhome-Challenge/https://x3ric.com/blog/posts/HackTheBox-Rhome-Challenge/Thu, 12 Dec 2024 09:20:00 +0800challengehtbcryptoaesprnghashEnter the challenge flag to unlock this writeup.https://x3ric.com/blog/posts/HackTheBox-RsaCtfTool-Challenge/https://x3ric.com/blog/posts/HackTheBox-RsaCtfTool-Challenge/Mon, 09 Dec 2024 09:20:00 +0800challengehtbcryptoaeshashRsaCtfTool: abuse the AES misuse, derive the missing key material, and decrypt the flag.https://x3ric.com/blog/posts/HackTheBox-Hybrid-Unifier-Challenge/https://x3ric.com/blog/posts/HackTheBox-Hybrid-Unifier-Challenge/Sat, 16 Nov 2024 09:20:00 +0800challengehtbcryptoaeshashHybrid Unifier: abuse the AES misuse, derive the missing key material, and decrypt the flag.https://x3ric.com/blog/posts/HackTheBox-SPG-Challenge/https://x3ric.com/blog/posts/HackTheBox-SPG-Challenge/Sat, 16 Nov 2024 09:20:00 +0800challengehtbcryptoaesprnghashSPG: reconstruct the generator state, derive the AES material, and decrypt the final ciphertext.https://x3ric.com/blog/posts/HackTheBox-Secure-Singning-Challenge/https://x3ric.com/blog/posts/HackTheBox-Secure-Singning-Challenge/Fri, 01 Nov 2024 09:20:00 +0800challengehtbcryptoxorhashSecure Singning: derive the XOR key stream, invert the transform, and recover the flag.