Computer encryption is…Computer encryption is…

Based on the Based on the science of science of

cryptographycryptography

Encryption Padlock AnalogyEncryption Padlock Analogy

Anybody can lock a padlock…

but, it takes a key to unlock it!

Symmetric key encryptionSymmetric key encryption

In In encryptionencryption, the word , the word symmetricsymmetric means means those cases where those cases where the same the same keykey both both

encrypts and encrypts and decrypts. decrypts.

Asymmetric key encryptionAsymmetric key encryption

Type of encryption in Type of encryption in which an encryption which an encryption

key (the public key) is key (the public key) is used to encrypt a used to encrypt a

message, and message, and another encryption another encryption

key (the private key) key (the private key) is used to decrypt the is used to decrypt the

message. message.

Public Key SecurityPublic Key Security

SSLSSL TLSTLS (Secure Sockets Layer) (Transport Layer Security)(Secure Sockets Layer) (Transport Layer Security)

Other Security ToolsOther Security Tools Checksum Checksum CRC (Cyclic Redundancy Check)CRC (Cyclic Redundancy Check)

If a single character in the data is changed, If a single character in the data is changed, then the data has been corrupted.then the data has been corrupted.

Checksum or CRC e4d909c290d0fb1ca068ffaddf22cbd0

35d91262b3c3ec8841b54169588c97f7

Not identical

Checksum or CRC

Ciphers or codes = algorithms.Ciphers or codes = algorithms.

Most cryptography used today Most cryptography used today relies on computers relies on computers

because of thebecause of the

speed and securityspeed and security

computers providecomputers provide

in cracking codes. in cracking codes.

Hashing AlgorithmHashing Algorithm

Alice

Bob

Alice

Bob

Alice

Bob

Alice

Bob

Bob

Alice

+

+

= Different Color

= Different Color

+

+

+

+ = Same Color

= Same Color

One-way function*

*Example of two- way mathematical function = light switch.

Encryption + AuthenticationEncryption + Authentication

PasswordsPasswordsPass cardsPass cardsDigital SignaturesDigital SignaturesFingerprint scan Fingerprint scan Retina scan Retina scan Face Scan Face Scan Voice identification Voice identification

Why do we need encryption?Why do we need encryption?

•Credit-card information •Social Security numbers •Private correspondence •Personal details •Sensitive school information •Bank-account information

But wait…there’s more!But wait…there’s more!

http://btwikilmc.pbworks.com/Encryption

http://www.aptv.org/aptplus/