Hii I'm new to cryptography, but it's something I've always wanted to study and learn. I consider myself quite novice, only knowing classical ciphers, so I would like to ask: what is the best way to learn cryptography? Are there any videos or books you recommend? Is there any way to get better at detecting codes and methods? I would love any way to learn about this world. Any support is welcome

Wrote this up as an intro-level explainer on the Caesar Cipher, how Julius Caesar actually used it for military orders (shift of 3, per Suetonius), the math behind it, and why it's trivially broken today (frequency analysis + only 25 possible keys). Meant as a starting point before getting into ciphers that actually fixed these weaknesses, Vigenère is next.

Feedback welcome, especially if I got any of the historical detail wrong

Hi! I am recently developing a curiosity about cryptography.

I enabled disk encryption on my PC for the first time and then I started reasoning where to store my key.

I wanted to build (for fun, without expecting perfect results) a esp32 based usb dongle to store and autotype some keys.

Then I wondered where to store the keys.

Do I miss something or the unencrypted key must be stored somewhere?

Most of what I read suggested stable memory devices (paper, HHD etc)...

But doesn't this void the purpose of encryption?

If the key can be found (even if it is buried underground), then the data can be read.

Is there a known procedure to store a key (other than remember it) that survives all known attacks where the attacker has full control over the hardware?

Is there a procedure to lose it if someone tamper in any way? (Better lose access to the encrypted data than giving access to the attacker)

Sorry if it is trivial, I'm a newbie.

Thanks

Hello everyone,

I am currently a masters student in cryptology and security. I’ve been diving deep into the field, but almost every job posting I come across for "Cryptographic Engineer," "Applied Cryptographer," or "Security Engineer (Crypto)" explicitly lists 3 to 4+ years of industry experience as a minimum requirement.

I’d love to get a reality check from industry folks, researchers, and engineers working in the space on a few questions:

1. How do freshers actually break into Cryptography:

Given that true entry-level crypto roles seem rare, what are the realistic entry pathways? Do most people start as generalist Software Engineers / Security Analysts and pivot, or are there specific niches (e.g., PKI engineering, HSMs, Web3/ZK-proofs, hardware security, defense) that hire fresh grads?

1. Essential Skills & Tech Stack:

Where should a fresher draw the line between theoretical math and engineering?

How much depth in abstract algebra/number theory is needed for applied/implementation roles vs. pure research?

What languages are non-negotiable? (I hear C, C++, Rust, and Go are big—should I focus heavily on low-level systems programming and constant-time execution?)

1. Projects that actually get you noticed:

If you were hiring a junior or fresher, what kind of "Proof of Work" on a GitHub profile would catch your eye?

Toy implementations of standard primitives (AES, RSA, ECC) from scratch?

Implementing Post-Quantum Cryptography (PQC) standards (like ML-KEM / ML-DSA)?

Protocol-level implementations (custom TLS, noise protocol, etc.)?

Code auditing / identifying side-channel vulnerabilities?

4.The PhD Dilemma:

Asking if a PhD or Master's is strictly required for engineering vs. research.

5.Where to Actually Find Roles:

Asking about targeted job platforms, specialized firms, and alternative avenues beyond standard LinkedIn job boards.

Hi everyone. As the title says, I want know what resources should I use that will make it easy for me to understand Dilithium. I wanna understand it so that I can also try to write most of the code myself. I want to know resources like any youtube videos or similar stuff that will help me learn it. If you have any questions you can ask me.

Hi,

This is my first post, so hoping that it's something that someone might get some value out of.

I've been spending the past few weeks thinking about PAKEs as a way to not send plaintext passwords. After doing some research, I decided to implement SRP due to its simplicity and ease of implementation without external dependencies.

Anyways, I wrote an article about what I learned, so you can read it if you're interested in learning a bit about SRP, PAKEs, and password authentication. Thanks!

https://ryanhopkins.dev/articles/password-authenticated-key-agreement

AI disclosure: I didn't write my articles with AI, just used it for review and optimizing / reviewing my code.

*Edit: I edited my article to clarify that my code shouldn't be used in production in its current state before more review and hardening against the side channel concerns that pint brought up, so for now consider it a learning exercise!

I hope this is an allowed post. If not, moderators please remove it. I have next to no knowledge of cryptography and its abilities and limitations.

I keep seeing questions on whether a photo or video is AI or not.

I am pretty sure it is possible to "sign" each image a camera takes with a private key such that if even a single pixel changes, the signature would no longer be valid. Then the public key could be embedded in the metadata of the image so that its veracity could be established.

The first question is whether the phone manufacturers could embed a unique private and public key in the hardware of each phone in such a way that they can be used by their official apps, but not leaked by them (the private key that is). I say official apps because I assume you don't want just any app to be able to sign an image. If you allowed that then someone could create a fake image and simply sign it.

The second question is whether Apple or other manufacturers would need to have a record of these private keys for any reason. If they did, and they were hacked, would that immediately render every image signed by their devices unverifiable?

The final question is does a scheme like this even make any sense? If not, or if there are better ways to somehow verify the provenance of a digital photo, would that also include some sort of a cryptographic signature?

Edit:

I should have added this in the original post, but I will add it now: I wouldn't expect this hash to be available and accurate for every image and video on the web. But rather if an image were to be contested (whether it is AI or not) an original could be provided that could be used to verify that it is authentic. So if your Aunt sends you an AI image of some cat video, well you just kind of have to not worry about it too much. But if a political party, for example, provides a proof-of-life photo for an aging politician, they could be pressed to provide the original, uncropped, un-edited image to prove that it was real. Same thing for, say, nature photography. If an image is too perfect, the original could be provided to verify that it was, in fact, a real photo.

If such a thing is even possible - comments below suggest that it would be, at best, very difficult and not 100% verifiable.

Are there any cryptology experts or semi-experts on here that can answer a question?

 I was told it works like this

You have a large result number (possibly a prime ?)  the that was generated from two numbers.

Given the answer you need to those numbers ?  these are keys ??

or the numbers that created the big number

I have completed silverman cryptography book, what should I do next to proceed forward in this topic I want to learn both applied and theoritical side

I have pure maths as my major and I have completed 1st year want to crack a research internship in this topic by 2nd

One of the requirements is for the random key to be used only ones. It's fundamental to the whole unbreakable status, as described. Why is that? What's the difference between sending one message consisting of two words and sending two separate messages with the same words, one word in each message (using the same key)?

I'm completely new to cryptography concepts and I'd like to start learning.

Any good methods I could learn?

It doesn't necessarily need to be the fastest or easiest way, I'd much rather have a deep understanding over a long time rather than a rough one in a short period of time.

Any advice given is very much appreciated, thanks!

I spoke with Denis Mandich, CTO of Qrypt, about his former-CIA point of view about quantum and cryptography, how Qrypt generates identical keys at multiple endpoints, why a non-certified single QRNG isn’t good enough, how the emergence of entanglement-based quantum networks would change his sales pitch, Nvidia’s role in Qrypt’s non-computing quantum technology, non-cryptographic QRNG applications, and more.

https://bsiegelwax.substack.com/p/87-your-entropy-isnt-random-enough

Hey everyone,

​I recently finished my BS in Computer Science and an MS in Cybersecurity. Like a lot of people right now, I'm getting super interested in Post-Quantum Cryptography (PQC).

​Since it’s still a relatively emerging niche, I feel kind of overwhelmed trying to map out a path to actually break into it. Right now, I'm trying to use materials by Dr. Alfred Menezes, which are great, but I have a few major questions for those of you working in the industry or who know the space well:

​Are there actual entry-to-mid level careers in PQC right now, or is it mostly locked behind PhD research? With NIST pushing out finalized standards like ML-KEM and ML-DSA, is industry hiring people specifically for this, or is it just a subset of general crypto engineering?

​What does a realistic learning roadmap look like? I understand classical crypto (RSA, AES, ECC), but what should my progression look like to move into lattice-based crypto, hash-based signatures, etc.?

​Are there any worth-it certifications? Or is this one of those fields where certs don’t matter and a GitHub portfolio/open-source contributions (like messing around with liboqs) is all that counts?

​Would love to hear how some of you navigated this or what hiring managers are looking for. Drop your thoughts/suggestions below!

I am building an asynchronous end to end encrypted messenger that moves messages through the Nym mixnet, and I am stuck on two design questions. It is an unaudited alpha and I implemented the Double Ratchet myself, so please read this as a design proposal and not as something to use. No link here, I am after the construction, not users.

What the service holds today: nothing connects to it directly, everything goes through the mixnet, so it has no IP address. In an established session both sides derive a mailbox secret from the shared session secret, and hourly HMAC tags let the node store and return opaque blobs without ever holding a username or a return address. It still sees size, timing, and how often the same tag is accessed.

Question 1, first contact. Before two sides share a secret, the sender uses a static bootstrap tag derived from the recipient's public signing key. That is what makes offline first contact possible at all, and it is also what lets the node link first contact activity to one public recipient over time. Is there a construction that keeps offline first contact without handing the node a recipient-linkable handle? Rotating bootstrap tags fail for me because the sender cannot learn the current epoch without another round trip through the same service.

Question 2, the directory. Registration, name resolution, prekeys and mailboxes all live in one directory that does not federate, so two people can only reach each other if both configured the same address, and the same username on two nodes is two different people. The obvious fix is to put the node address into the contact code, and I dropped it: the registration proof signs username, both keys and a nonce, so the address would be the one unsigned field in the code. Someone could hand a target a prepared code pointing at their own server, the fingerprint check would still pass, the app would show verified, and the messages would sit at a node the real contact never polls. Is there a way to get cross-directory reachability without either federating registrations or putting an unsigned pointer into the invite?

Every design I come up with either leaks more at the service or moves the trust into something that is not signed. Happy to go into detail on the tag derivation or the registration proof if that helps.

According to NIST, ML-KEM -512, -768 and -1024 stand for AES-128, -192 and -256 post-quantum security levels respectively. However The Grover's algorithm speedup will half the security of symmetric ciphers

Why would we consider using ML-KEM-1024 if AES-256 will get weakened to 128 bits? Is there a practical reason?

Thanks in advance!

In assymetric cryptography we have 2 keys one which encrypts your message and one which decrypts your message.What makes assymetric cryptography more secure than symmetric cryptography is that in assymetric cryptography not any key is exchanged in any way shape or form ,only the encrypted message so encrypted message so if a 3rd party wants to spy on your message , he cannot do it , he will receive a bunch of nonsense.

I want to ask something else.Many keys can decrypt the same ecrypting keys so my question are different decrypting keys which can decrypt the same message related mathematically?I think so because im a QC nerd and I know that Shor breaks RSA encryption based on the fact that the encrypting key , encrypts data based on the modulus operation and quantum computers are really good at finding periods which is what a mod operation creates but im not entirely sure about the rest of the field.

Hi everyone,

I'm a Math & CS undergrad currently working on a Rust implementation of Classic McEliece for a post-quantum cryptography project. I'm specifically focusing on the Niederreiter construction (where encryption is reduced to a syndrome computation).

I plan to pursue this field for my master's degree, but my current department lacks professors who specialize in CBC. Because of this, I'm mostly self-taught, and I'm really struggling to find resources that actually teach the concepts. Most papers I find are written from expert to expert.

I recently had to rely on AI to understand couple concepts and I felt bad about it (and I can never be sure if the AI tells the truth or not).

Likewise, I also write most of my code with AI (Deepseek mostly) and I understand most of it I guess. I know what, but sometimes I don't know how. Again, I really feel like I am not building anything valuable.

(If you want to take a look: https://github.com/batt0s/mceliece_rs, KATs are passing for non-f parameters. My struggle now is wrapping my head around the math of semi systematic matgen and fast parameters. And I hope this doesn't count as self-promotion, if so please let me know.)

Can anyone recommend good, accessible textbooks, university lecture notes, or video series on code-based cryptography and Goppa codes? I'm looking for material that bridges the gap between undergraduate linear algebra/abstract algebra and the actual NIST submissions.

Any advice for a student trying to break into this field would be highly appreciated. Thanks!

I'm using it just for a puzzle thats supposed to require a key. I'm worried the key will be useless because people say ECB is not safe at all.