ACM Summer School - IIIT Bangalore
Author: Ananth Adiga
I wanted to summarize what happened on the 10th day of summer school i.e 21st of June. Prof. Srinivas Vivek started the day by giving out a formal definition and break down of the word " cryptography ".
Krypto's - Hidden/Secret
Graphia- To write
So basically hiding your message so that only the person who knows the secret can access it.
The very same definition is can modified to fit in the field of computer science. Encrypting the message to stop unwanted access. Without cryptography, safe banking wouldn't be possible, your credit card details would be surfing around the internet.
cryptography provides us with the following
->Authentication
->Confidentiality
Authentication guarantees that only person with access can read/use the message.
Confidentiality guarantees the safety of the message. To keep the message secret in other words.
Cryptography overlaps with four fields namely social science, politics, law, economics. All these are interlinked and it is very much needed. Consider cryptography without law, what will happen? It's really hard to imagine cryptography without law. If there is no law that governs cryptography then it crumbles. Example- Postcard if there is no law that governs the illegal access of your postcard then anyone can open it and read sensitive details.
let's consider the first use of cryptography, it was in the 16th century a person called cypher introduced cryptography to the world. The concept was simple, you take a message and use a key to convert that to a non-human readable form and pass it, only the person with the key can read it. Key basically can be visualized as actual key and a lock. You place the message inside and lock it and the person with the key can open it.
To give a better explanation I would take a simple example. Consider John who wants to send a message to Ted but to do so he should ask Alex who is a messenger to deliver it to Ted and John wants the message to be encrypted. So he decided he in encrypts the message with a key
Message- " I ran out of money "
The encrypted message "D udq rxw ri prqhb"
Key 3
What do you think of the encrypted message? It seems to be encrypted right? So how did the message " I ran out of money " converted into "D udq rxw ri prqhb"? That's a big question mark. But the answer to that question is simple, you take the message and add 3 to each and every letter, a+3 is converted to 'd' same way all the rest of the letter.
This was a prolific method for some time but soon people started to crack it and they needed a better method so slowly one by one new method which was robust were built and in some time people started to crack it so this war of creating a robust method and cracking it continued, even today this war exists.
Today we have a method called RSA 1024 which stands for Rivest, Shamir, and Adelman. These three are the creator of this method. It all started with with a number less than 1024 maybe 128 but people started to crack it and then they moved to RSA 512 and then it was cracked and now we are at 1028 which quantum computers can solve easily.
So what does this number quantifies to? This number indicates a 1024 long prime number. p=1024 bits long prime number which is really huge and you multiply with q which is also a 1024 bit prime number so what you get is 2 power 11-bit number 'n' which is a composite number. A composite number is a number which can be divided by 2 or more numbers but prime numbers can only be divided by 1 and itself. So we use this 'n' in the future calculation. The important thing here is that if you know p and q from n then you can crack RSA 1024, let's be practical its really difficult to know p and q cause n is huge.
This was a short summary of the day, I haven't covered many topics which was taught that day, so by this I want to end this blog.
Thank you.
Author: Ananth Adiga
I wanted to summarize what happened on the 10th day of summer school i.e 21st of June. Prof. Srinivas Vivek started the day by giving out a formal definition and break down of the word " cryptography ".
Krypto's - Hidden/Secret
Graphia- To write
So basically hiding your message so that only the person who knows the secret can access it.
The very same definition is can modified to fit in the field of computer science. Encrypting the message to stop unwanted access. Without cryptography, safe banking wouldn't be possible, your credit card details would be surfing around the internet.
cryptography provides us with the following
->Authentication
->Confidentiality
Authentication guarantees that only person with access can read/use the message.
Confidentiality guarantees the safety of the message. To keep the message secret in other words.
Cryptography overlaps with four fields namely social science, politics, law, economics. All these are interlinked and it is very much needed. Consider cryptography without law, what will happen? It's really hard to imagine cryptography without law. If there is no law that governs cryptography then it crumbles. Example- Postcard if there is no law that governs the illegal access of your postcard then anyone can open it and read sensitive details.
let's consider the first use of cryptography, it was in the 16th century a person called cypher introduced cryptography to the world. The concept was simple, you take a message and use a key to convert that to a non-human readable form and pass it, only the person with the key can read it. Key basically can be visualized as actual key and a lock. You place the message inside and lock it and the person with the key can open it.
To give a better explanation I would take a simple example. Consider John who wants to send a message to Ted but to do so he should ask Alex who is a messenger to deliver it to Ted and John wants the message to be encrypted. So he decided he in encrypts the message with a key
Message- " I ran out of money "
The encrypted message "D udq rxw ri prqhb"
Key 3
What do you think of the encrypted message? It seems to be encrypted right? So how did the message " I ran out of money " converted into "D udq rxw ri prqhb"? That's a big question mark. But the answer to that question is simple, you take the message and add 3 to each and every letter, a+3 is converted to 'd' same way all the rest of the letter.
This was a prolific method for some time but soon people started to crack it and they needed a better method so slowly one by one new method which was robust were built and in some time people started to crack it so this war of creating a robust method and cracking it continued, even today this war exists.
Today we have a method called RSA 1024 which stands for Rivest, Shamir, and Adelman. These three are the creator of this method. It all started with with a number less than 1024 maybe 128 but people started to crack it and then they moved to RSA 512 and then it was cracked and now we are at 1028 which quantum computers can solve easily.
So what does this number quantifies to? This number indicates a 1024 long prime number. p=1024 bits long prime number which is really huge and you multiply with q which is also a 1024 bit prime number so what you get is 2 power 11-bit number 'n' which is a composite number. A composite number is a number which can be divided by 2 or more numbers but prime numbers can only be divided by 1 and itself. So we use this 'n' in the future calculation. The important thing here is that if you know p and q from n then you can crack RSA 1024, let's be practical its really difficult to know p and q cause n is huge.
This was a short summary of the day, I haven't covered many topics which was taught that day, so by this I want to end this blog.
Thank you.
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