Fixed spelling errors in comments

Also:
- Improved top-level README
- Added details on examples present in sodium directory to it's Readme

Author: tleonhardt

README.md

@@ -17,6 +17,19 @@ This repository contains some practical code examples of using the following cry
 
 File Contents
 =============
+
+Build-related and Miscellaneous
+-------------------------------
+* CMakeLists.txt
+    * CMake file for building the mbedTLS C code projects
+* mbedtls
+       * Directory containing the mbedTLS C code
+* sodium
+    * Directory containing libsodium examples, headers, and Windows pre-compiled library
+    * See the Readme.md in this directory for more info on these examples
+    
+Symmetric Encryption
+--------------------
 * aes_gcm.c
     * Simple self-contained C code example of using AES-256 in Galois Counter Mode (GCM) using hard-coded everything
 * aes_gcm_cryptography.py
@@ -26,24 +39,27 @@ File Contents
     * Takes arguments on command line and produces output to file
 * aesgcm_file.py
     * Python code example of file-based AES-256 GCM, works with aesgcm_file.c
-* CMakeLists.txt
-    * CMake file for building the mbedTLS C code projects
+    
+Key Exchange
+------------
 * ecdh.c
     * Elliptic Curve Diffie-Hellman key exchange C code example
 * ecdh.py
     * Elliptic Curve Diffie-Hellman key exchange Python code example
+    
+Key Derivation
+--------------
 * kdf.c
     * Key Derivation Function (KDF) C code example
 * kdf.py
     * Key Derivation Function (KDF) Python code example
-* mbedtls
-    * Directory containing the mbedTLS C code
+    
+Digital Signatures
+------------------
 * rsa_signature.c
     * RSA Signature C code example
 * rsa_signature.py
     * RSA Signature Python code example
-* sodium
-    * Directory containing libsodium examples, headers, and Windows pre-compiled library
 
 
 Building

aesgcm_file.py

@@ -10,7 +10,7 @@
 Additional means of verifying integrity such as HMAC are not necessary.
 
 NOTE: There is a better way to do AES-GCM in Cryptography version 2.0 or newer using the AES-GCM construction which is
-composed of the AES block cipher utilizing GCM mode.  This should be compatible with Cryptograhpy 1.7 or newer.
+composed of the AES block cipher utilizing GCM mode.  This should be compatible with Cryptography 1.7 or newer.
 
 This is intended to be used in conjunction with teh "aesgcm_file.c" example code for demonstrating interoperability
 between Python's Cryptography module and the mbed TLS C library for AES-256 in GCM mode.

kdf.c

@@ -5,8 +5,8 @@
  * mbedtls_pkcs5_pbkdf2_hmac() function in the pkcs5.h/.c files.
  *
  * PBDKF2 is a KDF with sliding computation cost aimed to reduce the vulnerability of encrypted keys to brute force
- * attacks.  PBKDF2 is part of RSA Laboratorie's Public-Key Cryptography Standards (PKCS) series, specifically PKCS#5
- * v2.0, also published as Internet Engineering Task Force's RFC 2898.  It supercedes PBKDF1, which could only produce
+ * attacks.  PBKDF2 is part of RSA Laboratory's Public-Key Cryptography Standards (PKCS) series, specifically PKCS#5
+ * v2.0, also published as Internet Engineering Task Force's RFC 2898.  It supersedes PBKDF1, which could only produce
  * keys up to 160 bits long.
  *
  * There are better KDF functions available which address weaknesses in PBDKF2, but PBKDF2 is widely available in most

nacl_sign.py

@@ -45,7 +45,7 @@
     with open(input_filename, 'rb') as msg_file:
         msg = msg_file.read()
 
-    # Sign a message with the signing key - this also containes the original message at the end
+    # Sign a message with the signing key - this also contains the original message at the end
     sig = signing_key.sign(msg)
 
     # Save the signature to an output file

rsa_sign.c

@@ -12,7 +12,7 @@
  *  - filename.sig - signature is saved to filename.sig where "filename" is the complete input filename
  *
  * Notes:
- *  This uses the Probabilisitc Signature Scheme (PSS) standardized as part of PKCS#1 v2.1 along with SHA-512 hashes.
+ *  This uses the Probabilistic Signature Scheme (PSS) standardized as part of PKCS#1 v2.1 along with SHA-512 hashes.
  */
 
 #if !defined(MBEDTLS_CONFIG_FILE)
@@ -56,7 +56,7 @@ int main( void )
 
 
 // Set RSA padding scheme, use PKCS_V21 for PKCS#1 v2.1 PSS probabilistic signatures or PKCS_V15 for older PKCS#1 v1.5
-// The RSA Probabilisitc Signature Scheme (PSS) should be used since it is more secure.
+// The RSA Probabilistic Signature Scheme (PSS) should be used since it is more secure.
 // However, some older encryption libraries only support the older deterministic PKCS#1 v.15 scheme
 //#define RSA_PADDING MBEDTLS_RSA_PKCS_V21
 #define RSA_PADDING MBEDTLS_RSA_PKCS_V15

rsa_sign.py

@@ -14,7 +14,7 @@
  *  - filename.sig - signature is saved to filename.sig where "filename" is the complete input filename
  *
  * Notes:
- *  This uses the Probabilisitc Signature Scheme (PSS) standardized as part of PKCS#1 v2.1 along with SHA-512 hashes.
+ *  This uses the Probabilistic Signature Scheme (PSS) standardized as part of PKCS#1 v2.1 along with SHA-512 hashes.
 """
 import sys
 
@@ -69,7 +69,7 @@ def print_usage() -> None:
 
     # Instantiate an instance of AsymmetricPadding to use
     if RSA_PADDING == PSS_PADDING:
-        # PKCS#1 v2.1 probabilistic padding sheme (PSS)
+        # PKCS#1 v2.1 probabilistic padding scheme (PSS)
         padding = padding.PSS(mgf=padding.MGF1(hashes.SHA512()),  # A mask generation function object
                               salt_length=padding.PSS.MAX_LENGTH)  # The length of the salt
     else:

rsa_verify.c

@@ -12,7 +12,7 @@
  *  - signature has been saved to filename.sig where "filename" is the complete input filename
  *
  * Notes:
- *  This uses the Probabilisitc Signature Scheme (PSS) standardized as part of PKCS#1 v2.1 along with SHA-512 hashes.
+ *  This uses the Probabilistic Signature Scheme (PSS) standardized as part of PKCS#1 v2.1 along with SHA-512 hashes.
  */
 
 #if !defined(MBEDTLS_CONFIG_FILE)
@@ -53,7 +53,7 @@ int main( void )
 #include <string.h>
 
 // Set RSA padding scheme, use PKCS_V21 for PKCS#1 v2.1 PSS probabilistic signatures or PKCS_V15 for older PKCS#1 v1.5
-// The RSA Probabilisitc Signature Scheme (PSS) should be used since it is more secure.
+// The RSA Probabilistic Signature Scheme (PSS) should be used since it is more secure.
 // However, some older encryption libraries only support the older deterministic PKCS#1 v.15 scheme
 //#define RSA_PADDING MBEDTLS_RSA_PKCS_V21
 #define RSA_PADDING MBEDTLS_RSA_PKCS_V15

rsa_verify.py

@@ -14,7 +14,7 @@
  *  - signature has been saved to filename.sig where "filename" is the complete input filename
  *
  * Notes:
- *  This uses the Probabilisitc Signature Scheme (PSS) standardized as part of PKCS#1 v2.1 along with SHA-512 hashes.
+ *  This uses the Probabilistic Signature Scheme (PSS) standardized as part of PKCS#1 v2.1 along with SHA-512 hashes.
 """
 import sys
 import traceback

sodium/Readme.md

@@ -58,3 +58,45 @@ make
 ```
 
 This will generate the executables in the build directory.
+
+
+File Contents
+=============
+
+Installation Verification
+-------------------------    
+* hello_sodium.c
+    * "hello world" code to make sure you have libsodium installed and are linking to it correctly
+    
+Symmetric Encryption
+--------------------
+These examples use the simple [crypto_secretbox](https://download.libsodium.org/doc/secret-key_cryptography/authenticated_encryption.html) 
+API which is an [authenticated encryption](https://en.wikipedia.org/wiki/Authenticated_encryption) (AE) cryptographic 
+primitive that combines an [XSalsa20](https://download.libsodium.org/doc/advanced/xsalsa20.html) 
+stream cipher with a [Poly1305](https://en.wikipedia.org/wiki/Poly1305) MAC.  This API is very easy to use and is 
+particularly suitable for use by newcomers to cryptography.  If you have need for authenticating additional data which 
+is transmitted in an unencrypted fashion, then you may prefer an AEAD primitive instead.
+
+* nacl_symmetric_gen.c
+    * Generates a random 256-bit (32-byte) secret symmetric key for use with the **secretbox** API
+* nacl_encrypt_file.c
+    * Encrypts a file using libsodium's **secretbox** secret-key authenticated encryption routines and adds a MAC of the ciphertext
+* nacl_decrypt_file.c
+    * Authenticates and decrypts a ciphertext file encrypted using libsodium's **secretbox** secret-key encryption routines
+
+Public-key Digital Signatures
+-----------------------------
+These examples use the simple [crypto_sign](https://download.libsodium.org/doc/public-key_cryptography/public-key_signatures.html) 
+API which is a public-key digital signature cryptographic primitive based on elliptic curves and uses the 
+[Ed25519](https://ed25519.cr.yp.to) algorithm.
+
+* nacl_genkey.c
+    *  Generates a random Ed25519 Secret(signing)/Public(verifying) key pair using libsodium
+* nacl_sign.c
+    * Uses libsodium to sign a message using the Ed25519 digital signature algorithm
+* nacl_verify.c
+    * Uses libsodium to verify a signed message using the Ed25519 digital signature algorithm
+* ed25519_sodium_pynacl.c
+    * Round trip "unit test" of using libsodium Ed25519 digital signature code along with PyNacl digital signature code
+    
+

sodium/ed25519_sodium_pynacl.c

@@ -27,7 +27,7 @@ int main(int argc, char *argv[])
     if (sodium_init() < 0)
     {
         /* panic! the library couldn't be initialized, it is not safe to use */
-        printf("ERROR: The sodium library couldn't be initialied!\n");
+        printf("ERROR: The sodium library couldn't be initialized!\n");
         return EXIT_FAILURE;
     }