Fix small typos in cryptography-overview.md

cryptography-overview.md

@@ -14,11 +14,11 @@ We shall learn later that behind this simple **AES encryption**, there are **man
 
 # What is Cryptography?
 
-**Cryptography **is the science of providing **security **and **protection **of information. It is used everywhere in our digital world: when you open a Web site, send an email or connect to the WiFi network. What's why developers should have **at least basic understanding of cryptography** and how to use crypto algorithms and crypto libraries, to understand hashing, symmetric and asymmetric ciphers and encryption schemes, as well as digital signatures and the cryptosystems and algorithms behind them.
+**Cryptography **is the science of providing **security **and **protection **of information. It is used everywhere in our digital world: when you open a Web site, send an email or connect to the WiFi network. That's why developers should have **at least basic understanding of cryptography** and how to use crypto algorithms and crypto libraries, to understand hashing, symmetric and asymmetric ciphers and encryption schemes, as well as digital signatures and the cryptosystems and algorithms behind them.
 
 ## Encryption and Keys
 
-Cryptography deals with **storing and transmitting data in a secure way**, such that only those, for whom it is intended, can read and process it. This may involve **encrypting and decrypting data** using symmetric or asymmetric encryption schemes , where one or more **keys** are used to transform data from plain to encrypted form and back.
+Cryptography deals with **storing and transmitting data in a secure way**, such that only those, for whom it is intended, can read and process it. This may involve **encrypting and decrypting data** using symmetric or asymmetric encryption schemes, where one or more **keys** are used to transform data from plain to encrypted form and back.
 
 **Symmetric encryption** \(like AES, Twofish and ChaCha20\) uses the same key to encrypt and decrypt messages, while **asymmetric encryption** uses a **public-key cryptosystem** \(like RSA or ECC\) and a key-pair: public key \(encryption key\) and corresponding private key \(decryption key\). Encryption algorithms are often combined in encryption schemes \(like AES-256-CTR-HMAC-SHA-256, ChaCha20-Poly1305 or ECIES-secp256k1-AES-128-GCM\).