, Introduction to cryptography
What is it?
A method to turn regular information (plaintext) into a secret code (ciphertext) so only someone with the right key
can decode it. Example: sharing a coded secret with a friend
Relation to everyday life
Texting: Imagine you send a text to your friend about a surprise birthday party. If someone intercepts the
message, you wouldn't want them to know about the party. If the message is encrypted (coded), even if someone
sees it, they won't understand it.
Banking: When you use an ATM card, your bank uses cryptography to ensure that your transaction is secure. Your
pin number and transaction details are protected using these cryptographic techniques. So, even if a bad actor tries
to intercept this information, they won't be able to misuse it because it's encrypted.
Online Shopping: When you shop online and enter your credit card details, these details are encrypted by the
website. This ensures that even if someone tries to steal this information during its journey from your computer to
the website's server, they can't because it's all coded.
Passwords: When you set a password for an account, the system often doesn't store the exact password. Instead,
it stores an encrypted (coded) version of it. This way, even if someone breaks into the system, they can't just see
Chronology of Cryptography and steal your password easily.
Evolution Communication: Apps like WhatsApp use encryption so that only the sender and receiver can read the message.
Even if someone tries to intercept your chats, they can't read them without the decryption key.
1960s: (military)
Safeguard national secrets Digital Age:
& strategies Encryption and decryption • Need: Rise of computers & communication in
Goal: securely send a message ensuring only the 1960s increased demand for data
1970s: the intended recipient can understand it protection.
IBM kickstarts DES • Noteworthy: DES (especially important for
development Encryption: changing the original message using a code financial institutions' e-commerce).
Decryption: changing the coded message back to the original Public-Key Cryptography:
1976s: • Pioneers: Diffie & Hellman (1976)
Groundbreaking concepts by
introduced the concept.
Diffie & Hellman
P=D(E(P)) • RSA: 1978 - by Rivest, Shamir, Adleman.
• El Gamal: 1985 - based on the discrete
1978s:
P : Plaintext (original message) logarithm problem.
RSA unveiled by
E(P) : Encrypting P, resulting in ciphertext Digital Signatures:
Rivest,Shamir & Adleman
D(E(P)) : Decrypting the ciphertext to get back P • Value: Top contribution from public-key
1980s: cryptography.
Major advancement in • Standardization: 1991 - first international
Cryptography: A brief overview standard (RSA-based). 1994 - U.S.
cryptography
Initial Days: approved the Digital Signature Standard (El
1985: • Objective: Ensure message confidentiality. Gamal- based).
El Gamal's schemes based on • Tools: Mostly pen and paper. Ongoing Evolution:
the discrete logarithm • Historical Timeline: Begins ~4000 years ago with • Status: Constant advancement in systems,
problem the Egyptians. methods, and security.
World Affairs: • Modern Relevance: Emergence of new
1991s: • Impact: Influenced outcomes of both World Wars. standards, products, and infrastructure
ISO/IEC 9796 (Establishes • Users: Primarily militaries, diplomats, governments reflects the growing need for information
digital signature standards till the 1960s. security.
Cryptography starting as a military tools,
expended its horizon, adapting to technological
advances, indicating its sustained importance
What is it?
A method to turn regular information (plaintext) into a secret code (ciphertext) so only someone with the right key
can decode it. Example: sharing a coded secret with a friend
Relation to everyday life
Texting: Imagine you send a text to your friend about a surprise birthday party. If someone intercepts the
message, you wouldn't want them to know about the party. If the message is encrypted (coded), even if someone
sees it, they won't understand it.
Banking: When you use an ATM card, your bank uses cryptography to ensure that your transaction is secure. Your
pin number and transaction details are protected using these cryptographic techniques. So, even if a bad actor tries
to intercept this information, they won't be able to misuse it because it's encrypted.
Online Shopping: When you shop online and enter your credit card details, these details are encrypted by the
website. This ensures that even if someone tries to steal this information during its journey from your computer to
the website's server, they can't because it's all coded.
Passwords: When you set a password for an account, the system often doesn't store the exact password. Instead,
it stores an encrypted (coded) version of it. This way, even if someone breaks into the system, they can't just see
Chronology of Cryptography and steal your password easily.
Evolution Communication: Apps like WhatsApp use encryption so that only the sender and receiver can read the message.
Even if someone tries to intercept your chats, they can't read them without the decryption key.
1960s: (military)
Safeguard national secrets Digital Age:
& strategies Encryption and decryption • Need: Rise of computers & communication in
Goal: securely send a message ensuring only the 1960s increased demand for data
1970s: the intended recipient can understand it protection.
IBM kickstarts DES • Noteworthy: DES (especially important for
development Encryption: changing the original message using a code financial institutions' e-commerce).
Decryption: changing the coded message back to the original Public-Key Cryptography:
1976s: • Pioneers: Diffie & Hellman (1976)
Groundbreaking concepts by
introduced the concept.
Diffie & Hellman
P=D(E(P)) • RSA: 1978 - by Rivest, Shamir, Adleman.
• El Gamal: 1985 - based on the discrete
1978s:
P : Plaintext (original message) logarithm problem.
RSA unveiled by
E(P) : Encrypting P, resulting in ciphertext Digital Signatures:
Rivest,Shamir & Adleman
D(E(P)) : Decrypting the ciphertext to get back P • Value: Top contribution from public-key
1980s: cryptography.
Major advancement in • Standardization: 1991 - first international
Cryptography: A brief overview standard (RSA-based). 1994 - U.S.
cryptography
Initial Days: approved the Digital Signature Standard (El
1985: • Objective: Ensure message confidentiality. Gamal- based).
El Gamal's schemes based on • Tools: Mostly pen and paper. Ongoing Evolution:
the discrete logarithm • Historical Timeline: Begins ~4000 years ago with • Status: Constant advancement in systems,
problem the Egyptians. methods, and security.
World Affairs: • Modern Relevance: Emergence of new
1991s: • Impact: Influenced outcomes of both World Wars. standards, products, and infrastructure
ISO/IEC 9796 (Establishes • Users: Primarily militaries, diplomats, governments reflects the growing need for information
digital signature standards till the 1960s. security.
Cryptography starting as a military tools,
expended its horizon, adapting to technological
advances, indicating its sustained importance
